Standard Methods For the Examination of Water and Wastewater 22th edition

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Standard 
Methods
For the Examination of� 
Water and Wastewater™
Edited by� 
Eugene W. Rice
Rodger B. Baird
Andrew D. Eaton
Lenore S. Clesceri
 
American Public Health Association®
American Water Works Association®
Water Environment Federation®
22nD E D i t i o n
 
 
TABLE OF CONTENTS 
 
Page 
Part 1000 INTRODUCTION 
1010 INTRODUCTION 
A. Scope and Application of Methods 
B. Statistics 
C. Glossary 
D. Dilution/Concentration Options 
1020 QUALITY ASSURANCE 
A. Introduction 
B. Quality Control 
C. Quality Assessment 
1030 DATA QUALITY 
A. Introduction 
B. Measurement Uncertainty 
C. Method Detection Level 
D. Data Quality Objectives 
E. Checking Analyses’ Correctness 
1040 METHOD DEVELOPMENT AND EVALUATION 
A. Introduction 
B. Method Validation 
C. Collaborative Testing 
1050 EXPRESSION OF RESULTS 
A. Units 
B. Significant Figures 
1060 COLLECTION AND PRESERVATION OF SAMPLES 
A. Introduction 
B. Collection of Samples 
C. Sample Storage and Preservation 
 
 
1080 REAGENT WATER 
A. Introduction 
B. Methods for Preparing Reagent-Grade Water 
C. Reagent Water Quality 
1090 LABORATORY OCCUPATIONAL HEALTH AND SAFETY 
A. Introduction 
B. Safe Laboratory Practices 
C. Laboratory Facility/Fixed Equipment 
D. Hazard Evaluation 
E. Personal Protective Equipment 
F. Worker Protection Medical Program 
G. Provisions for Work with Particularly Hazardous Substances 
H. Biological Safety 
I. Radiological Safety 
J. Chemical Hygiene Plan 
1100 WASTE MINIMIZATION AND DISPOSAL 
A. Introduction 
B. Waste Minimization 
C. Waste Treatment and Disposal 
 
Part 2000 PHYSICAL AND AGGREGATE PROPERTIES 
2010 INTRODUCTION 
2020 QUALITY ASSURANCE/QUALITY CONTROL 
 A. Introduction 
 B. Quality Control Practices 
2110 APPEARANCE 
2120 COLOR 
A. Introduction 
B. Visual Comparison Method 
C. Spectrophotometric—Single-Wavelength Method (Proposed) 
D. Spectrophotometric—Multi-Wavelength Method 
E. Tristimulus Spectrophotometric Method 
F. ADMI Weighted-Ordinate Spectrophotometric Method 
2130 TURBIDITY 
A. Introduction 
B. Nephelometric Method 
2150 ODOR 
A. Introduction 
B. Threshold Odor Test 
2160 TASTE 
A. Introduction 
B. Flavor Threshold Test (FTT) 
C. Flavor Rating Assessment (FRA) 
2170 FLAVOR PROFILE ANALYSIS 
A. Introduction 
B. Flavor Profile Analysis 
 
 
2310 ACIDITY 
A. Introduction 
B. Titration Method 
2320 ALKALINITY 
A. Introduction 
B. Titration Method 
2330 CALCIUM CARBONATE SATURATION 
A. Introduction 
B. Indices Indicating Tendency of a Water to Precipitate or Dissolve CaCO3 
C. Indices Predicting the Quantity of CaCO3 That Can Be Precipitated or Dissolved 
D. Graphical and Computer Methods for CaCO3 Indices 
2340 HARDNESS 
A. Introduction 
B. Hardness by Calculation 
C. EDTA Titrimetric Method 
2350 OXIDANT DEMAND/REQUIREMENT 
A. Introduction 
B. Chlorine Demand/Requirement 
C. Chlorine Dioxide Demand/Requirement 
D. Ozone Demand/Requirement—Batch Method 
E. Ozone Demand/Requirement—Semi-Batch Method 
2510 CONDUCTIVITY 
A. Introduction 
B. Laboratory Method 
2520 SALINITY 
A. Introduction 
B. Electrical Conductivity Method 
C. Density Method 
D. Algorithm of Practical Salinity 
2530 FLOATABLES 
A. Introduction 
B. Particulate Floatables 
C. Trichlorotrifluoroethane-Soluble Floatable Oil and Grease 
2540 SOLIDS 
A. Introduction 
B. Total Solids Dried at 103–105°C 
C. Total Dissolved Solids Dried at 180°C 
D. Total Suspended Solids Dried at 103–105°C 
E. Fixed and Volatile Solids Ignited at 550°C 
F. Settleable Solids 
G. Total, Fixed, and Volatile Solids in Solid and Semisolid Samples 
2550 TEMPERATURE 
 A. Introduction 
 B. Laboratory and Field Methods 
2560 PARTICLE COUNTING AND SIZE DISTRIBUTION 
A. Introduction 
 
 
B. Electrical Sensing Zone Method 
C. Light-Blockage Methods 
D. Light-Scattering Method 
2570 ASBESTOS 
A. Introduction 
B. Transmission Electron Microscopy Method 
2580 OXIDATION–REDUCTION POTENTIAL (ORP) 
A. Introduction 
B. Oxidation–Reduction Potential Measurement in Clean Water 
2710 TESTS ON SLUDGES 
A. Introduction 
B. Oxygen-Consumption Rate 
C. Settled Sludge Volume 
D. Sludge Volume Index 
E. Zone Settling Rate 
F. Specific Gravity 
G. Capillary Suction Time 
H. Time-to-Filter 
I. Modified Settled Sludge Volume 
2720 ANAEROBIC SLUDGE DIGESTER GAS ANALYSIS 
A. Introduction 
B. Volumetric Method 
C. Gas Chromatographic Method 
2810 DISSOLVED GAS SUPERSATURATION 
A. Introduction 
B. Direct-Sensing Membrane-Diffusion Method 
 
Part 3000 METALS 
3010 INTRODUCTION 
 A. General Discussion 
 B. Sampling and Sample Preservation 
 C. General Precautions 
3020 QUALITY ASSURANCE/QUALITY CONTROL 
A. Introduction 
B. Quality Control Practices 
3030 PRELIMINARY TREATMENT OF SAMPLES 
A. Introduction 
B. Filtration for Dissolved and Suspended Metals 
C. Treatment for Acid-Extractable Metals 
D. Digestion for Metals 
E. Nitric Acid Digestion 
F. Nitric Acid-Hydrochloric Acid Digestion 
G. Nitric Acid-Sulfuric Acid Digestion 
H. Nitric Acid-Perchloric Acid Digestion 
I. Nitric Acid-Perchloric Acid-Hydrofluoric Acid Digestion 
J. Dry Ashing 
 
 
K. Microwave-Assisted Digestion 
3110 METALS BY ATOMIC ABSORPTION SPECTROMETRY 
3111 METALS BY FLAME ATOMIC ABSORPTION SPECTROMETRY 
A. Introduction 
B. Direct Air-Acetylene Flame Method 
C. Extraction/Air-Acetylene Flame Method 
D. Direct Nitrous Oxide-Acetylene Flame Method 
E. Extraction/Nitrous Oxide-Acetylene Flame Method 
3112 METALS BY COLD-VAPOR ATOMIC ABSORPTION SPECTROMETRY 
A. Introduction 
B. Cold-Vapor Atomic Absorption Spectrometric Method 
3113 METALS BY ELECTROTHERMAL ATOMIC ABSORPTION SPECTROMETRY 
A. Introduction 
B. Electrothermal Atomic Absorption Spectrometric Method 
3114 ARSENIC AND SELENIUM BY HYDRIDE GENERATION/ATOMIC ABSORPTION SPECTROMETRY 
A. Introduction 
B. Manual Hydride Generation/Atomic Absorption Spectrometric Method 
C. Continuous Hydride Generation/Atomic Absorption Spectrometric Method 
3120 METALS BY PLASMA EMISSION SPECTROSCOPY 
A. Introduction 
B. Inductively Coupled Plasma (ICP) Method 
3125 METALS BY INDUCTIVELY COUPLED PLASMA/MASS SPECTROMETRY 
A. Introduction 
B. Inductively-Coupled Plasma/Mass Spectrometry (ICP/MS) Method 
3130 METALS BY ANODIC STRIPPING VOLTAMMETRY 
A. Introduction 
B. Determination of Lead, Cadmium, and Zinc 
3500-Al ALUMINUM 
A. Introduction 
B. Eriochrome Cyanine R Method 
3500-As ARSENIC 
A. Introduction 
B. Silver Diethyldithiocarbamate Method 
3500-Ca CALCIUM 
A. Introduction 
B. EDTA Titrimetric Method 
3500-Cr CHROMIUM 
A. Introduction 
B. Colorimetric Method 
C. Ion Chromatographic Method 
3500-Cu COPPER 
A. Introduction 
B. Neocuproine Method 
C. Bathocuproine Method 
3500-Fe IRON 
A. Introduction 
 
 
B. Phenanthroline Method 
3500-Pb LEAD 
A. Introduction 
B. Dithizone Method 
3500-Li LITHIUM 
A. Introduction 
B. Flame Emission Photometric Method 
3500-Mg MAGNESIUM 
A. Introduction 
B. Calculation Method 
3500-Mn MANGANESE 
A. Introduction 
B. Persulfate Method 
3500-K POTASSIUM 
A. Introduction 
B. Flame Photometric Method 
C. Potassium-Selective Electrode Method 
3500-Se SELENIUM 
A. Introduction 
B. Sample Preparation 
C. Colorimetric Method 
D. Determination of Volatile Selenium 
E. Determination of Nonvolatile Organic Selenium Compounds 
3500-Na SODIUM 
A. Introduction 
B. Flame Emission Photometric Method 
3500-Sr STRONTIUM 
A. Introduction 
B. Flame Emission Photometric Method 
3500-V VANADIUM 
A. Introduction 
B. Gallic Acid Method 
3500-Zn ZINC 
A. Introduction 
B. Zincon Method 
3500 OTHER METALS 
 3500-Sb Antimony 
 3500-Ba Barium 
 3500-Be Beryllium 
 3500-Bi Bismuth 
 3500-B Boron 
 3500-Cd Cadmium 
 3500-Cs Cesium 
 3500-Co
Cobalt 
 3500-Ga Gallium 
 3500-Ge Germanium 
 
 
 3500-Au Gold 
 3500-In Indium 
 3500-Ir Iridium 
 3500-Hg Mercury 
 3500-Mo Molybdenum 
 3500-Ni Nickel 
 3500-Os Osmium 
 3500-Pd Palladium 
 3500-Pt Platinum 
 3500-Re Rhenium 
 3500-Rh Rhodium 
 3500-Ru Ruthenium 
 3500-Ag Silver 
 3500-Te Tellurium 
 3500-Tl Thallium 
 3500-Th Thorium 
 3500-Sn Tin 
 3500-Ti Titanium 
 3500-U Uranium 
 
Part 4000 INORGANIC NONMETALLIC CONSTITUENTS 
4010 INTRODUCTION 
4020 QUALITY ASSURANCE/QUALITY CONTROL 
A. Introduction 
B. Quality Control Practices 
4110 DETERMINATION OF ANIONS BY ION CHROMATOGRAPHY 
A. Introduction 
B. Ion Chromatography with Chemical Suppression of Eluent Conductivity 
C. Single-Column Ion Chromatography with Direct Conductivity Detection 
D. Ion Chromatographic Determination of Oxyhalides and Bromide 
4120 SEGMENTED CONTINUOUS FLOW ANALYSIS 
A. Introduction 
B. Segmented Flow Analysis Method 
4130 INORGANIC NONMETALS BY FLOW INJECTION ANALYSIS 
A. Introduction 
B. Quality Control 
4140 INORGANIC ANIONS BY CAPILLARY ION ELECTROPHORESIS 
A. Introduction 
B. Capillary Ion Electrophoresis with Indirect UV Detection 
4500-B BORON 
A. Introduction 
B. Curcumin Method 
C. Carmine Method 
4500-Br‾ BROMIDE 
A. Introduction 
B. Phenol Red Colorimetric Method 
 
 
 
C. (Reserved) 
D. Flow Injection Analysis 
4500-CO2 CARBON DIOXIDE 
A. Introduction 
B. Nomographic Determination of Free Carbon Dioxide and the Three Forms of 
Alkalinity 
C. Titrimetric Method for Free Carbon Dioxide 
D. Carbon Dioxide and Forms of Alkalinity by Calculation 
4500-CN‾ CYANIDE 
A. Introduction 
B. Preliminary Treatment of Samples 
C. Total Cyanide after Distillation 
D. Titrimetric Method 
E. Colorimetric Method 
F. Cyanide-Selective Electrode Method 
G. Cyanides Amenable to Chlorination after Distillation 
H. Cyanides Amenable to Chlorination without Distillation (Short-Cut Method) 
I. Weak Acid Dissociable Chloride 
J. Cyanogen Chloride 
K. Spot Testing for Sample Screening 
L. Cyanates 
M. Thiocyanate 
N. Total Cyanide after Distillation, by Flow Injection Analysis 
O. Total Cyanide and Weak Acid Dissociable Cyanide by Flow Injection Analysis 
4500-Cl CHLORINE (RESIDUAL) 
A. Introduction 
B. Iodometric Method I 
C. Iodometric Method II 
D. Amperometric Titration Method 
E. Low-Level Amperometric Titration Method 
F. DPD Ferrous Titrimetric Method 
G. DPD Colorimetric Method 
H. Syringaldazine (FACTS) Method 
I. Iodometric Electrode Technique 
4500-Cl‾ CHLORIDE 
A. Introduction 
B. Argentometric Method 
C. Mercuric Nitrate Method 
D. Potentiometric Method 
E. Automated Ferricyanide Method 
F. (Reserved) 
G. Mercuric Thiocyanate Flow Injection Analysis 
4500-ClO2 CHLORINE DIOXIDE 
A. Introduction 
B. Iodometric Method 
 
 
C. Amperometric Method I 
D. (Reserved) 
E. Amperometric Method II 
4500-F‾ FLUORIDE 
A. Introduction 
B. Preliminary Distillation Step 
C. Ion-Selective Electrode Method 
D. SPADNS Method 
E. Complexone Method 
F. (Reserved) 
G. Ion-Selective Electrode Flow Injection Analysis 
4500-H+ PH VALUE 
A. Introduction 
B. Electrometric Method 
4500-I IODINE 
A. Introduction 
B. Leuco Crystal Violet Method 
C. Amperometric Titration Method 
4500-I‾ IODIDE 
A. Introduction 
B. Leuco Crystal Violet Method 
C. Catalytic Reduction Method 
D. Voltammetric Method 
4500-IO3‾ IODATE 
A. Introduction 
B. Polarographic Method 
4500-N NITROGEN 
A. Introduction 
B. In-Line UV/Persulfate Digestion and Oxidation with Flow Injection Analysis 
C. Persulfate Method 
D. Conductimetric Determination of Inorganic Nitrogen 
4500-NH3 NITROGEN (AMMONIA) 
A. Introduction 
B. Preliminary Distillation Step 
C. Titrimetric Method 
D. Ammonia-Selective Electrode Method 
E. Ammonia-Selective Electrode Method Using Known Addition 
F. Phenate Method 
G. Automated Phenate Method 
H. Flow Injection Analysis 
4500-NO2‾ NITROGEN (NITRITE) 
A. Introduction 
B. Colorimetric Method 
4500-NO3‾ NITROGEN (NITRATE) 
A. Introduction 
B. Ultraviolet Spectrophotometric Screening Method 
 
 
C. Second-Derivative Ultraviolet Spectrophotometric Method (Proposed) 
D. Nitrate Electrode Method 
E. Cadmium Reduction Method 
F. Automated Cadmium Reduction Method 
G. (Reserved) 
H. Automated Hydrazine Reduction Method 
I. Cadmium Reduction Flow Injection Analysis 
4500-Norg NITROGEN (ORGANIC) 
A. Introduction 
B. Macro-Kjeldahl Method 
C. Semi-Micro Kjeldahl Method 
D. Block Digestion and Flow Injection Analysis 
4500-O OXYGEN (DISSOLVED) 
A. Introduction 
B. Iodometric Methods 
C. Azide Modification 
D. Permanganate Modification 
E. Alum Flocculation Modification 
F. Copper Sulfate-Sulfamic Acid Flocculation Modification 
G. Membrane Electrode Method 
4500-O3 OZONE (RESIDUAL) 
A. Introduction 
B. Indigo Colorimetric Method 
4500-P PHOSPHORUS 
A. Introduction 
B. Sample Preparation 
C. Vanadomolybdophosphoric Acid Colorimetric Method 
D. Stannous Chloride Method 
E. Ascorbic Acid Method 
F. Automated Ascorbic Acid Reduction Method 
G. Flow Injection Analysis for Orthophosphate 
H. Manual Digestion and Flow Injection Analysis for Total Phosphorus 
I. In-line UV/Persulfate Digestion and Flow Injection Analysis for Total Phosphorus 
J. Persulfate Method for Simultaneous Determination of Total Nitrogen and Total Phosphorus 
4500-KMnO4 POTASSIUM PERMANGANATE 
A. Introduction 
B. Spectrophotometric Method 
4500-SiO2 SILICA 
A. Introduction 
B. (Reserved) 
C. Molybdosilicate Method 
D. Heteropoly Blue Method 
E. Automated Method for Molybdate-Reactive Silica 
F. Flow Injection Analysis for Molybdate-Reactive Silica 
4500-S2- SULFIDE 
A. Introduction 
 
 
B. Separation of Soluble and Insoluble Sulfides 
C. Sample Pretreatment to Remove Interfering Substances or to Concentrate the Sulfide 
D. Methylene Blue Method 
E. Gas Dialysis, Automated Methylene Blue Method 
F. Iodometric Method 
G. Ion-Selective Electrode Method 
H. Calculation of Un-ionized Hydrogen Sulfide 
I. Distillation, Methylene Blue Flow Injection Analysis 
J. Acid-Volatile Sulfide 
4500-SO32- SULFITE 
A. Introduction 
B. Iodometric Method 
C. Phenanthroline Method 
4500-SO42- SULFATE 
A. Introduction 
B. (Reserved) 
C. Gravimetric Method with Ignition of Residue 
D. Gravimetric Method with Drying of Residue 
E. Turbidimetric Method 
F. Automated Methylthymol Blue Method 
G. Methylthymol Blue Flow Injection Analysis 
 
Part 5000 AGGREGATE ORGANIC CONSTITUENTS 
5010 INTRODUCTION 
A. General Discussion 
B. Sample Collection and Preservation 
5020 QUALITY ASSURANCE/QUALITY CONTROL 
 A. Introduction 
 B. Quality Control Practices 
5210 BIOCHEMICAL OXYGEN DEMAND (BOD) 
A. Introduction 
B. 5-Day BOD Test 
C. Ultimate BOD Test 
D. Respirometric Method 
5220 CHEMICAL OXYGEN DEMAND (COD) 
A. Introduction 
B. Open Reflux Method 
C. Closed Reflux, Titrimetric Method 
D. Closed Reflux, Colorimetric Method 
5310 TOTAL ORGANIC CARBON (TOC) 
A. Introduction 
B. High-Temperature Combustion Method 
C. Persulfate-Ultraviolet or Heated-Persulfate Oxidation Method 
 D. Wet Oxidation Method 
5320 DISSOLVED ORGANIC HALOGEN 
A. Introduction 
 
 
B. Adsorption-Pyrolysis-Titrimetric Method 
5510 AQUATIC HUMIC SUBSTANCES 
A. Introduction 
B. Diethylaminoethyl (DEAE) Method 
C. XAD Method 
5520 OIL AND GREASE 
A. Introduction 
B. Liquid-Liquid, Partition-Gravimetric Method 
C. Partition-Infrared Method 
D. Soxhlet Extraction Method 
E. Extraction Method for Sludge Samples 
F. Hydrocarbons 
G. Solid-Phase, Partition-Gravimetric Method 
5530 PHENOLS 
A. Introduction 
B. Cleanup Procedure 
C. Chloroform Extraction Method 
D. Direct Photometric Method 
5540 SURFACTANTS 
A. Introduction 
B. Surfactant Separation by Sublation 
C.
Anionic Surfactants as MBAS 
D. Nonionic Surfactants as CTAS 
5550 TANNIN AND LIGNIN 
A. Introduction 
B. Colorimetric Method 
5560 ORGANIC AND VOLATILE ACIDS 
A. Introduction 
B. Chromatographic Separation Method for Organic Acids 
C. Distillation Method 
D. Gas Chromatographic Method 
5710 FORMATION OF TRIHALOMETHANES AND OTHER DISINFECTION BY-PRODUCTS 
A. Introduction 
B. Trihalomethane Formation Potential (THMFP) 
C. Simulated Distribution System Trihalomethanes (SDS-THM) 
D. Formation of Other Disinfection By-Products (DBPs) 
5910 UV-ABSORBING ORGANIC CONSTITUENTS 
A. Introduction 
B. Ultraviolet Absorption Method 
 
Part 6000 INDIVIDUAL ORGANIC COMPOUNDS 
6010 INTRODUCTION 
A. General Discussion 
B. Sample Collection and Preservation 
C. Analytical Methods 
6020 QUALITY ASSURANCE/QUALITY CONTROL 
 
 
A. Introduction 
B. Quality Control Practices 
6040 CONSTITUENT CONCENTRATION BY GAS EXTRACTION 
A. Introduction 
B. Closed-Loop Stripping, Gas Chromatographic/Mass Spectrometric Analysis 
C. Purge and Trap Technique 
D. Solid-Phase Microextraction (SPME) 
E. Solid-Phase Microextracion (SPME) with CI GC/MS/MS 
6200 VOLATILE ORGANIC COMPOUNDS 
A. Introduction 
B. Purge and Trap Capillary-Column Gas Chromatographic/Mass Spectrometric Method 
C. Purge and Trap Capillary-Column Gas Chromatographic Method 
6211 METHANE 
A. Introduction 
B. Combustible-Gas Indicator Method 
C. Volumetric Method 
6231 1,2-DIBROMOETHANE (EDB) AND 1,2-DIBROMO-3-CHLOROPROPANE (DBCP) 
A. Introduction 
B. Liquid-Liquid Extraction Gas Chromatographic Method 
C. Purge and Trap Gas Chromatographic/Mass Spectrometric Method 
D. Purge and Trap Gas Chromatographic Method 
6232 TRIHALOMETHANES AND CHLORINATED ORGANIC SOLVENTS 
A. Introduction 
B. Liquid-Liquid Extraction Gas Chromatographic Method 
C. Purge and Trap Gas Chromatographic/Mass Spectrometric Method 
D. Purge and Trap Gas Chromatographic Method 
6251 DISINFECTION BY-PRODUCTS: HALOACETIC ACIDS AND TRICHLOROPHENOL 
A. Introduction 
B. Micro Liquid-Liquid Extraction Gas Chromatographic Method 
6252 DISINFECTION BY-PRODUCTS: ALDEHYDES 
A. Introduction 
B. PFBHA Liquid-Liquid Extraction Gas Chromatographic Method 
6410 EXTRACTABLE BASE/NEUTRALS AND ACIDS 
A. Introduction 
B. Liquid-Liquid Extraction Gas Chromatographic/Mass Spectrometric Method 
6420 PHENOLS 
A. Introduction 
B. Liquid-Liquid Extraction Gas Chromatographic Method 
C. Liquid-Liquid Extraction Gas Chromatographic/Mass Spectrometric Method 
6431 POLYCHLORINATED BIPHENYLS (PCBS) 
A. Introduction 
B. Liquid-Liquid Extraction Gas Chromatographic Method 
C. Liquid-Liquid Extraction Gas Chromatographic/Mass Spectrometric Method 
6440 POLYNUCLEAR AROMATIC HYDROCARBONS 
A. Introduction 
B. Liquid-Liquid Extraction Chromatographic Method 
 
 
C. Liquid-Liquid Extraction Gas Chromatographic/Mass Spectrometric Method 
6450 NITROSAMINES 
 A. Introduction 
 B. Carbonaceous-Resin Solid-Phase Extraction GC/MS Method 
 C. Micro Liquid-Liquid Extraction GC/MS Method 
6610 CARBAMATE PESTICIDES 
A. Introduction 
B. High-Performance Liquid Chromatographic Method 
6630 ORGANOCHLORINE PESTICIDES 
A. Introduction 
B. Liquid-Liquid Extraction Gas Chromatographic Method I 
 Appendix—Standardization of Magnesia-Silica Gel Column by Weight Adjustment Based on 
Adsorption of Lauric Acid 
C. Liquid-Liquid Extraction Gas Chromatographic Method II 
D. Liquid-Liquid Extraction Gas Chromatographic/Mass Spectrometric Method 
6640 ACIDIC HERBICIDE COMPOUNDS 
A. Introduction 
B. Micro Liquid-Liquid Extraction Gas Chromatographic Method 
6651 GLYPHOSATE HERBICIDE 
A. Introduction 
B. Liquid Chromatographic Post-Column Fluorescence Method 
6710 TRIBUTYL TIN 
 A. Introduction 
 B. Gas Chromatographic/Mass Spectrometric Method 
 C. Gas Chromatographic/Flame Photometric Detector Method 
 
Part 7000 RADIOACTIVITY 
7010 INTRODUCTION 
A. General Discussion 
B. Sample Collection and Preservation 
7020 QUALITY SYSTEM 
A. Quality Systems/Quality Assurance/Quality Control Program 
B. Quality Control for Wastewater Samples 
C. Statistics 
D. Calculation and Expression of Results 
7030 COUNTING INSTRUMENTS 
A. Introduction 
B. Description and Operation of Instruments 
7040 FACILITIES 
A. Counting Room 
B. Radiochemistry Laboratory 
C. Laboratory Safety 
D. Pollution Prevention 
E. Waste Management 
7110 GROSS ALPHA AND GROSS BETA RADIOACTIVITY (TOTAL, SUSPENDED, AND DISSOLVED) 
A. Introduction 
 
 
B. Evaporation Method for Gross Alpha-Beta 
C. Coprecipitation Method for Gross Alpha Radioactivity in Drinking Water 
7120 GAMMA-EMITTING RADIONUCLIDES 
A. Introduction 
B. Gamma Spectroscopic Method 
7500-Cs RADIOACTIVE CESIUM 
A. Introduction 
B. Precipitation Method 
7500-I RADIOACTIVE IODINE 
A. Introduction 
B. Precipitation Method 
C. Ion-Exchange Method 
D. Distillation Method 
7500-Ra RADIUM 
A. Introduction 
B. Precipitation Method 
C. Emanation Method 
D. Sequential Precipitation Method 
E. Gamma Spectroscopy Method 
7500-Rn RADON 
A. Introduction 
B. Liquid Scintillation Method 
7500-Sr TOTAL RADIOACTIVE STRONTIUM AND STRONTIUM-90 
A. Introduction 
B. Precipitation Method 
7500-3H TRITIUM 
A. Introduction 
B. Liquid Scintillation Spectrometric Method 
7500-U URANIUM 
A. Introduction 
B. Radiochemical Method 
C. Isotopic Method 
 
Part 8000 TOXICITY 
8010 INTRODUCTION 
A. General Discussion 
B. Terminology 
C. Basic Requirements 
D. Conducting Toxicity Tests 
E. Preparing Organisms for Toxicity Tests 
F. Toxicity Test Systems, Materials, and Procedures 
G. Calculating, Analyzing, and Reporting Results of Toxicity Tests 
H. Interpreting and Applying Results of Toxicity Tests 
I. Selected Toxicological Literature 
8020 QUALITY ASSURANCE AND QUALITY CONTROL IN LABORATORY TOXICITY TESTS 
A. General Discussion 
 
 
B. Elements of QA/QC 
8030 MUTAGENESIS 
A. Introduction 
B. Salmonella Microsomal Mutagenicity Test 
8050 BACTERIAL BIOLUMINESCENCE 
A. Introduction 
B. Bacterial Bioluminescence Test 
8070 P450 REPORTER GENE RESPONSE TO DIOXIN-LIKE ORGANIC COMPOUNDS 
A. Introduction 
B. The P450 RGS Test 
8071 COMET/SINGLE-CELL GEL ELECTROPHORESIS ASSAY FOR DETECTION OF DNA DAMAGE 
A. Introduction 
B. Comet/Single-Cell Gel Electrophoresis Assay 
8080 SEDIMENT POREWATER TESTING 
A. Introduction 
B. Sediment Collection and Storage 
C. Extraction of Sediment Pore Water 
D. Toxicity Testing Procedures 
8110 ALGAE 
8111 BIOSTIMULATION (ALGAL PRODUCTIVITY) 
A. General Principles 
B. Planning and Evaluating Algal Assays 
C. Apparatus 
D. Sample Handling 
E. Synthetic Algal Culture Medium 
F. Inoculum 
G. Test Conditions and Procedures 
H. Effect of Additions 
I. Data Analysis and Interpretation 
8112 PHYTOPLANKTON 
A. Introduction 
B. Inoculum 
C. Test Conditions and Procedures 
8113 MARINE MACROALGAE 
A. Introduction 
B. Selecting and Preparing Macrocystis pyrifera Sporophylls 
C. Toxicity Test Procedures 
D. Data Evaluation 
8200 AQUATIC FLOWERING PLANTS 
8211 DUCKWEED 
A. Introduction 
B. Selecting and Preparing Test Organisms 
C. Toxicity Test Procedure 
8220 AQUATIC EMERGENT PLANTS 
A. Introduction 
B. Selecting and Preparing Test Organisms 
 
 
C. Toxicity Test Procedure 
8310 CILIATED PROTOZOA 
A. Introduction 
B. Growth Inhibition Test with Freshwater Ciliate Colpidium campylum 
C. Chemotactic Test with Freshwater Ciliate Tetrahymena Thermophila 
D. Growth Inhibition Test with the Soil Ciliate Colpoda inflata 
8420 ROTIFERS 
A. Introduction 
B. Selecting and Preparing Testing Organisms 
C. Aquatic Toxicity Test Procedures 
8510 ANNELIDS 
A. Introduction 
B. Selecting and Preparing Test Organisms 
C. Toxicity Test Procedures 
D. Sediment Test Procedures Using the Marine Polychaete
Neanthes arenaceodentata 
E. Sediment Test Procedures using the Marine Polychaete Polydora cornuta 
F. Sediment Test Procedures Using the Freshwater and Marine Oligochaetes Pristina leidyi, 
Tubifex tubifex, and Lumbriculus variegatus 
G. Data Evaluation 
8610 MOLLUSKS 
A. Introduction 
B. Selecting and Preparing Test Organisms 
C. Short-Term Test Procedures Using Marine Mollusk Larvae 
D. Sediment Test Procedures Using Marine Bivalves 
E. Field Test Procedures Using Freshwater and Marine Bivalves 
8710 ARTHROPODS 
8711 DAPHNIA 
A. Introduction 
B. Selecting and Preparing Test Organisms 
C. Toxicity Test Procedures 
8712 CERIODAPHNIA 
A. Introduction 
B. Selecting and Preparing Test Organisms 
C. Toxicity Test Procedures 
8714 MYSIDS 
A. Introduction 
B. Selecting and Preparing Test Organisms 
C. Toxicity Test Procedures 
8740 DECAPODS 
A. Introduction 
B. Selecting and Preparing Test Organisms 
C. Toxicity Test Procedures 
D. Data Evaluation 
8750 AQUATIC INSECTS 
A. Introduction 
 B. Selecting and Preparing Test Organisms 
 
 
 C. Toxicity Test Procedures 
 D. Data Evaluation 
8810 ECHINODERM FERTILIZATION AND DEVELOPMENT 
A. Introduction 
B. Selecting and Preparing Test Organisms 
C. Echinoderm Fertilization Test 
D. Echinoderm Embryo Development Test 
8910 FISH 
A. Introduction 
B. Fish Selection and Culture Procedures 
C. Toxicity Test Procedures 
8921 FATHEAD MINNOW 
A. Introduction 
B. Culture and Maintenance of Test Organisms 
C. Toxicity Test Procedures 
8930 AMPHIBIANS (PROPOSED) 
A. Introduction 
B. Culture and Maintenance of Test Organisms 
C. Toxicity Test Procedures 
 
Part 9000 MICROBIOLOGICAL EXAMINATION 
9010 INTRODUCTION 
9020 QUALITY ASSURANCE/QUALITY CONTROL 
A. Introduction 
B. Intralaboratory Quality Control Guidelines 
C. Interlaboratory Quality Control 
9030 LABORATORY APPARATUS 
A. Introduction 
B. Equipment Specifications 
9040 WASHING AND STERILIZATION 
9050 PREPARATION OF CULTURE MEDIA 
A. General Procedures 
B. Water 
C. Media Specifications 
9060 SAMPLES 
A. Collection 
B. Preservation and Storage 
9211 RAPID DETECTION METHODS 
A. Introduction 
B. Seven-Hour Fecal Coliform Test 
C. Special Techniques 
9212 STRESSED MICROORGANISMS 
A. Introduction 
B. Recovery Enhancement 
9213 RECREATIONAL WATERS 
A. Introduction 
 
 
B. Swimming Pools 
C. Whirlpools 
D. Natural Bathing Beaches 
E. Membrane Filter Technique for Pseudomonas aeruginosa 
F. Multiple-Tube Technique for Pseudomonas aeruginosa 
9215 HETEROTROPHIC PLATE COUNT 
A. Introduction 
B. Pour Plate Method 
C. Spread Plate Method 
D. Membrane Filter Method 
E. Enzyme Substrate Method 
9216 DIRECT TOTAL MICROBIAL COUNT 
A. Introduction 
B. Epifluorescence Microscopic Method Using Acridine Orange 
9217 ASSIMILABLE ORGANIC CARBON 
A. Introduction 
B. Pseudomonas fluorescens Strain P-17, Spirillum Strain NOX Method 
9218 AEROBIC ENDOSPORES 
A. Introduction 
B. Membrane Filter Method 
9221 MULTIPLE-TUBE FERMENTATION TECHNIQUE FOR MEMBERS OF THE COLIFORM GROUP 
A. Introduction 
B. Standard Total Coliform Fermentation Technique 
C. Estimation of Bacterial Density 
D. Presence–Absence (P–A) Coliform Test 
E. Fecal Coliform Procedure 
F. Escherichia coli Procedure Using Fluorogenic Substrate 
G. Other Escherichia coli Procedures (PROPOSED) 
9222 MEMBRANE FILTER TECHNIQUE FOR MEMBERS OF THE COLIFORM GROUP 
A. Introduction 
B. Standard Total Coliform Membrane Filter Procedure 
C. Delayed-Incubation Total Coliform Procedure 
D. Thermotolerant (Fecal) Coliform Membrane Filter Procedure 
E. Delayed-Incubation Thermotolerant (Fecal) Coliform Procedure 
F. Klebsiella Membrane Filter Procedure 
G. MF Partition Procedures 
H. Simultaneous Detection of Total Coliform and E. coli by Dual-Chromogen Membrane Filter 
Procedure (PROPOSED) 
I. Simultaneous Detection of Total Coliform and E. coli by Fluorogen/Chromogen Membrane 
Filter Procedure (PROPOSED) 
9223 ENZYME SUBSTRATE COLIFORM TEST 
A. Introduction 
B. Enzyme Substrate Test 
9224 DETECTION OF COLIPHAGES 
A. Introduction 
B. Somatic Coliphage Assay 
 
 
C. Male-Specific Coliphage Assay Using Escherichia coli Famp 
D. Male-Specific Coliphage Assay Using Salmonella typhimurium WG49 
E. Single-Agar-Layer Method 
F. Membrane Filter Method 
9225 DIFFERENTIATION OF COLIFORM BACTERIA 
A. Introduction 
B. Culture Purification 
C. Identification 
D. Media, Reagents, and Procedures 
E. Reporting Results 
9230 FECAL STREPTOCOCCUS/STREPTOCOCCUS GROUPS 
A. Introduction 
B. Multiple-Tube Technique 
C. Membrane Filter Techniques 
D. Fluorogenic Substrate Enterococcus Test 
9240 IRON AND SULFUR BACTERIA 
A. Introduction 
B. Iron Bacteria 
C. Sulfur Bacteria 
D. Enumerating, Enriching, and Isolating Iron and Sulfur Bacteria 
E. Bacteria Living in Acidic Environments 
9245 NITRIFYING BACTERIA 
A. Introduction 
B. Multiple-Tube Method 
9250 DETECTION OF ACTINOMYCETES 
A. Introduction 
B. Actinomycete Plate Count 
9260 DETECTION OF PATHOGENIC BACTERIA 
A. Introduction 
B. Salmonella 
C. (Reserved) 
D. (Reserved) 
E. Shigella 
F. Diarrheagenic Escherichia coli 
G. Campylobacter 
H. Vibrio 
I. Leptospira 
J. Legionella 
K. Yersinia enterocolitica 
L. Aeromonas 
M. Mycobacterium 
9510 DETECTION OF ENTERIC VIRUSES 
A. Introduction 
B. Virus Concentration from Small Sample Volumes by Adsorption to and Elution from 
Microporous Filters 
C. Virus Concentration from Large Sample Volumes by Adsorption to and Elution from 
 
 
Microporous Filters 
D. Virus Concentration by Aluminum Hydroxide Adsorption-Precipitation 
E. Hydroextraction-Dialysis with Polyethylene Glycol 
F. Recovery of Viruses from Suspended Solids in Water and Wastewater 
G. Assay and Identification of Viruses in Sample Concentrates 
9610 DETECTION OF FUNGI 
A. Introduction 
B. Pour Plate Technique 
C. Spread Plate Technique 
D. Membrane Filter Technique 
E. Technique for Yeasts 
F. Zoosporic Fungi 
G. Aquatic Hyphomycetes 
H. Fungi Pathogenic to Humans 
9711 PATHOGENIC PROTOZOA 
A. Introduction 
B. Detection of Giardia and Cryptosporidium in Water 
C. Detection of Giardia and Cryptosporidium in Wastewater 
D. Infectivity of Cryptosporidium in Cell Culture 
 
Part 10000 BIOLOGICAL EXAMINATION 
10010 INTRODUCTION 
10200 PLANKTON 
A. Introduction 
B. Sample Collection 
C. Concentration Techniques 
D. Preparing Slide Mounts 
E. Microscopes and Calibrations 
F. Phytoplankton Counting Techniques 
G. Zooplankton Counting Techniques 
H. Chlorophyll 
I. Determination of Biomass (Standing Crop) 
J. Metabolic Rate Measurements 
10300 PERIPHYTON 
A. Introduction 
B. Sample Collection 
C. Sample Analysis 
D. Primary Productivity 
E. Interpreting and Reporting Results 
10400 MACROPHYTES 
A. Introduction 
B. Preliminary Survey 
C. Vegetation Mapping Methods 
D. Population Estimates 
E. Productivity 
10500 BENTHIC MACROINVERTEBRATES 
 
 
A. Introduction 
B. Sample Collection 
C. Sample Processing and Analysis 
D. Data Evaluation, Presentation, and Conclusions 
10600 FISHES 
A. Introduction 
B. Data Acquisition 
C. Sample Preservation 
D. Analysis of Collections 
E. Investigation of Fish Kills 
10700 BENTHIC MEIOFAUNA 
10750 NEMATOLOGICAL EXAMINATION 
A. Introduction 
B. Collection and Processing Techniques for Nematodes 
C. Illustrated Key to Freshwater Nematodes 
10900 IDENTIFICATION OF AQUATIC ORGANISMS 
A. Procedure in Identification 
B. Key to Major Groups of Aquatic Organisms (Plates 1–35) 
 Acknowledgements 
C. Key for Identification of Freshwater Algae Common in Water Supplies and Polluted Waters 
(Plates 1A, 1B, 28–35) 
D. Index to Illustrations 
E. Selected Taxonomic References 
 
PART 1000
INTRODUCTION
Part Coordinator
L. Malcolm Baker
JOINT TASK GROUP CHAIRS FOR THE 22ND EDITION
1020 Quality Assurance .............................................................................................Michael F. Delaney
1050 Expression of Results..........................................................................................L. Malcolm Baker
SUMMARY OF MAJOR CHANGES SINCE 2005
The Introduction now includes more information on statistics and dilution/concentration operations,
as well as an expanded glossary. Quality Assurance (1020) and Data Quality (1030) were significantly
revised to stay abreast of regulatory requirements and clarify the quality control steps considered to be
an integral part of each test method. The revisions also are intended to ensure that these sections are
consistent with newly revised Sections 2020, 3020, 4020, 5020, 6020, and 7020.
Expression of Results (1050) contains an expanded explanation of units and scientific and engineer-
ing notation, analyte nomenclature, and propagation of error. A discussion of equivalents is also new.
The table of sampling and handling requirements in Collection and Preservation of Samples (1060)
has been updated.
1010 INTRODUCTION*
1010 A. Scope and Application of Methods
The procedures described in Standard Methods for the Exam-
ination of Water and Wastewater are intended for use in analyz-
ing a wide range of waters, including surface water, ground
water, saline water, domestic and industrial water supplies, cool-
ing or circulating water, boiler water, boiler feed water, and
treated and untreated municipal and industrial wastewaters. In
recognition of the unity of the water, wastewater, and watershed
management fields, the analytical methods are categorized based
on constituent, not type of water.
An effort has been made to present methods that apply gen-
erally. When alternative methods are necessary for samples of
different composition, the basis for selecting the most appropri-
ate method is presented as clearly as possible. In specific in-
stances (e.g., samples with extreme concentrations or otherwise
unusual compositions or characteristics), analysts may have to
modify a method for it to be suitable. If so, they should plainly
state the nature of the modification when reporting the results.
Certain procedures are intended for use with sludges and
sediments. Here again, the effort has been made to present
methods with the widest possible application. However, these
methods may require modification or be inappropriate for chem-
ical sludges or slurries, or other samples with highly unusual
composition.
Most of the methods included here have been endorsed by
regulators. Regulators may not accept procedures that were
modified without formal approval.
Methods for analyzing bulk water-treatment chemicals are not
included. American Water Works Association committees pre-
pare and issue standards for water treatment chemicals.
Laboratories that desire to produce analytical results of known
quality (i.e., results are demonstrated to be accurate within a
specified degree of uncertainty) should use established quality
control (QC) procedures consistently. Part 1000 provides a de-
tailed overview of QC procedures used in the individual standard
methods as prescribed throughout Standard Methods. Other sec-
tions of Part 1000 address laboratory safety, sampling proce-
dures, and method development and validation. Material pre-
sented in Part 1000 is not necessarily intended to be prescriptive
nor to replace or supersede specific QC requirements given in
individual sections of this book. Parts 2000 through 9000 contain
sections describing QC practices specific to the methods in the
respective Parts; these practices are considered to be integral to
the methods. Most individual methods will contain explicit in-
structions to be followed for that method (either in general or for
certain regulatory applications).
Similarly, the overview of topics covered in Part 1000 is not
intended to replace or be the sole basis for technical education
and training of analysts. Rather, the discussions are intended as
aids to augment and facilitate reliable use of the test procedures
herein. Each Section in Part 1000 contains references that can be
reviewed to gain more depth or details for topics of interest.
1010 B. Statistics
1. Normal Distribution
If a measurement is repeated many times under essentially
identical conditions, the results of each measurement (x) will be
distributed randomly about a mean value (arithmetic average)
because of uncontrollable or experimental uncertainty. If an
infinite number of such measurements were accumulated, then
the individual values would be distributed in a curve similar to
those shown in Figure 1010:1. Figure 1010:1A illustrates the
Gaussian (normal) distribution, which is described precisely by
the mean (�) and the standard deviation (�). The mean (average)
is simply the sum of all values (xi) divided by the number of
values (n).
� � ��xi�/n for entire population
Because no measurements are repeated infinitely, it is only
possible to make an estimate of the mean (x�) using the same
summation procedure but with n equal to a finite number of
repeated measurements (10, 20, 30, etc.):
x� � ��xi�/n for estimated mean
The standard deviation of the entire population measured is as
follows:
� � ���xi� ��
2/n�1/2
The empirical estimate of the sample standard deviation (s) is
as follows:
s � ���xi� x� �
2/�n � 1��1/2
The standard deviation fixes the width (spread) of the
normal distribution and consists of a fixed fraction of the
* Reviewed by Standard Methods Committee, 2011.
1
measurements that produce the curve. For example, 68.27%
of the measurements lie within � � 1�, 95.45% between
within � � 2�, and 99.73% within � � 3�. (It is sufficiently
accurate to state that 95% of the values are within � � 2� and
99% within � � 3�.) When values are assigned to the � �
multiples, they are called confidence limits, and the range
between them is called the confidence interval. For example,
10 � 4 indicates that the confidence limits are 6 and 14, and
the confidence interval ranges from 6 to 14.
Another useful statistic is the standard error of the mean
(��)—the standard deviation divided by the square root of the
number of values ��/�n). This is an estimate of sampling accu-
racy; it implies that the mean of another sample from the same
population would have a mean within some multiple of ��. As
with �, 68.27% of the measurements lie within � � 1��,
95.45% within � � 2��, and 99.73% within � � 3��. In
practice, a relatively small number of average values is available,
so the confidence intervals about the mean are expressed as:
x� � ts/�n
where t has the following values for 95% confidence intervals:
n t n t
2 12.71 5 2.78
3 4.30 10 2.26
4 3.18 � 1.96
Using t compensates for the tendency of a small number of
values to underestimate uncertainty. For n � 15, it is common to
use t 	 2 to estimate the 95% confidence interval.
Still another statistic is the relative standard deviation (�/�)
with its estimate (s/x¯), also known as the coefficient of variation
(CV), which commonly is expressed as a percentage. This sta-
tistic normalizes � and sometimes facilitates direct comparisons
among analyses involving a wide range of concentrations. For
example, if analyses at low concentrations yield a result of 10 �
1.5 mg/L and at high concentrations yield a result of 100 � 8
mg/L, the standard deviations do not appear comparable. How-
ever, the percent relative standard deviations are 100 (1.5/10) 	
Figure 1010:1. Three types of frequency distribution curves—normal Gaussian (A), positively skewed (B), and negatively skewed
(C)—and their measures of central tendency: mean, median, and mode. Courtesy: L. Malcolm Baker.
INTRODUCTION (1010)/Statistics
2
INTRODUCTION
(1010)/Statistics
15% and 100 (8/100) 	 8%, indicating that the variability is not
as great as it first appears.
The mean, median, and mode for each curve in Figure 1010:1
were calculated as follows:
1) Mean is the value at the 50th percentile level, or arithmetic
average,
2) Mode is the value that appears most frequently, and
3) Median1 is estimated as follows:
Median� 1⁄3 �2� Mean 
 Mode)
2. Log-Normal Distribution
In many cases, the results obtained from analyzing environ-
mental samples will not be normally distributed [i.e., a graph of
the data distribution will be obviously skewed (see Figure
1010:1B and C)] so the mode, median, and mean will be dis-
tinctly different. To obtain a nearly normal distribution, convert
the measured variable results to logarithms and then calculate x�
and s. The antilogarithms of x� and s are the estimates of geo-
metric mean (x�g) and geometric standard deviation (sg). The
geometric mean is defined as:
x�g� ���xi��
1/n� antilog �1/n�� log �xi��
3. Least Square Curve Fitting
Calibration curve data can be fitted to a straight line or
quadratic curve by the least squares method, which is used to
determine the constants of the curve that the data points best fit.
To do this, choose the equation that best fits the data points and
assume that x is the independent variable and y is the dependent
variable (i.e., use x to predict the value of y). The sum of the
squares of the differences between each actual data point and its
predicted value are minimized.
For a linear least squares fit of
y � mx � b
the slope (a1) and the y intercept1–3 (a0) are computed as follows:
m �
��x�y/n � �xy�
���x�2/n � �x2�
b �
�y � m�x
n
The correlation coefficient1–3 (degree of fit) is:
r � m� ��x�y/n� � �xy�y2� ��y�2/n �
0.5
The best fit is when r 	 1. There is no fit when r 	 0.
For a quadratic least squares fit of
y 	 a2 x2 
 a1 x 
 a0,
the constants (a0, a1, and a2)1�3 must be calculated. Typically,
these calculations are performed using software provided by
instrument manufacturers or independent software vendors. For
a more detailed description of the algebraic manipulations, see
the cited references.
In this case, the correlation coefficient1 is:
r � �1 � ��y
2 � a0�y� a1�xy� a2�x2y�
��y2 � 1
n
��y�2� �
0.5
4. Rejecting Data
In a series of measurements, one or more results may differ
greatly from the others. Theoretically, no result should be arbi-
trarily rejected because it may indicate either a faulty technique
(casting doubt on all results) or a true variant in the distribution.
In practice, it is permissible to reject the result of any analysis in
which a known error occurred. In environmental studies, ex-
tremely high and low concentrations of contaminants may indi-
cate either problematic or uncontaminated areas, so they should
not be rejected arbitrarily.
An objective test for outliers has been described.4 If a set of
data is ordered from low to high (xL, x2 . . . xH) and the mean and
standard deviation are calculated, then suspected high or low
outliers can be tested via the following procedure. First, calculate
the statistic T using the discordancy test for outliers:
T 	 (xH – x¯)/s for a high value, or
T 	 (x�� xL)/s for a low value.
Second, compare T with the value in Table 1010:I for either a
TABLE 1010:I. CRITICAL VALUES FOR 5% AND 1% TESTS OF
DISCORDANCY FOR A SINGLE OUTLIER IN A NORMAL SAMPLE
Number of
Measurements
n
Critical Value
5% 1%
3 1.15 1.15
4 1.46 1.49
5 1.67 1.75
6 1.82 1.94
7 1.94 2.10
8 2.03 2.22
9 2.11 2.32
10 2.18 2.41
12 2.29 2.55
14 2.37 2.66
15 2.41 2.71
16 2.44 2.75
18 2.50 2.82
20 2.56 2.88
30 2.74 3.10
40 2.87 3.24
50 2.96 3.34
60 3.03 3.41
100 3.21 3.60
120 3.27 3.66
SOURCE: BARNET, V. & T. LEWIS. 1995. Outliers in Statistical Data, 3rd ed. John
Wiley & Sons, New York, N.Y.
INTRODUCTION (1010)/Statistics
3
INTRODUCTION (1010)/Statistics
5% or 1% level of significance for the number of measurements
(n). If T is larger than that value, then xH or xL is an outlier.
Further information on statistical techniques is available else-
where.5–7
5. References
1. SPIEGEL, M.R. & L.J. STEPHENS. 1998 Schaum’s Outline—Theory and
Problems of Statistics. McGraw-Hill, New York, N.Y.
2. LAFARA, R.L. 1973. Computer Methods for Science and Engineering.
Hayden Book Co., Rochelle Park, N.J.
3. TEXAS INSTRUMENTS, INC. 1975. Texas Instruments Programmable
Calculator Program Manual ST1. Statistics Library, Dallas, Texas.
4. BARNETT, V. & T. LEWIS. 1995. Outliers in Statistical Data, 3rd ed.,
John Wiley & Sons, New York, N.Y.
5. NATRELLA, M.G. 1963. Experimental Statistics, Handbook 91. Na-
tional Bur. Standards, Washington, D.C.
6. SNEDECOR, G.W. & W.G. COCHRAN. 1980. Statistical Methods. Iowa
State University Press, Ames.
7. VERMA, S.P. & A. QUIROZ-RUIZ. 2006. Critical values for 22 discor-
dancy test variants for outliers in normal samples up to sizes 100, and
applications in science and engineering. Revista Mexicana de Cien-
cias Geologicas 23(3):302.
1010 C. Glossary
This glossary defines concepts, not regulatory terms. It is not
intended to be all-inclusive.
Accuracy—estimate of how close a measured value is to the true
value; includes expressions for bias and precision.
Analyte—the element, compound, or component being analyzed.
Bias—consistent deviation of measured values from the true
value, caused by systematic errors in a procedure.
Calibration check standard—standard used to determine an
instrument’s accuracy between recalibrations.
Confidence coefficient—the probability (%) that a measurement
will lie within the confidence interval (between the confidence
limits).
Confidence interval—set of possible values within which the
true value will lie with a specified level of probability.
Confidence limit—one of the boundary values defining the
confidence interval.
Detection levels—various levels in use are:
Instrument detection level (IDL)—the constituent concentration
that produces a signal greater than five times the instrument’s
signal:noise ratio. The IDL is similar to the critical level and
criterion of detection, which is 1.645 times the s of blank
analyses (where s is the estimate of standard deviation).
Lower level of detection (LLD) [also called detection level and
level of detection (LOD)]—the constituent concentration in
reagent water that produces a signal 2(1.645)s above the mean
of blank analyses. This establishes both Type I and Type II
errors at 5%.
Method detection level (MDL)—the constituent concentration
that, when processed through the entire method, produces a
signal that has 99% probability of being different from the
blank. For seven replicates of the sample, the mean must be
3.14s above the blank result (where s is the standard deviation
of the seven replicates). Compute MDL from replicate
measurements of samples spiked with analyte at concen-
trations more than one to five times the estimated MDL.
The MDL will be larger than the LLD because typically
7 or less replicates are used. Additionally, the MDL will
vary with matrix.
Reporting level (RL)—the lowest quantified level within an
analytical method’s operational range deemed reliable
enough, and therefore appropriate, for reporting by the
laboratory. RLs may be established by regulatory mandate
or client specifications, or arbitrarily chosen based on a
preferred level of acceptable reliability. Examples of
RLs typically used (besides the MDL) include:
Level of quantitation (LOQ)/minimum quantifiable level
(MQL)—the analyte concentration that produces a signal
sufficiently stronger than the blank, such that it can be
detected with a specified level of reliability during
routine operations. Typically, it is the concentration
that produces a signal 10s above the reagent
water
blank signal, and should have a defined precision and
bias at that level.
Minimum reporting level (MRL)—the minimum concen-
tration that can be reported as a quantified value for a
target analyte in a sample. This defined concentration
is no lower than the concentration of the lowest cali-
bration standard for that analyte and can only be used
if acceptable QC criteria for this standard are met.
Duplicate—1) the smallest number of replicates (two), or 2)
duplicate samples (i.e., two samples taken at the same time
from one location) (field duplicate) or replicate of laboratory
analyzed sample.
Fortification—adding a known quantity of analyte to a sample or
blank to increase the analyte concentration, usually for the
purpose of comparing to test result on the unfortified sample
and estimating percent recovery or matrix effects on the test to
assess accuracy.
Internal standard—a pure compound added to a sample extract
just before instrumental analysis to permit correction for in
efficiencies.
Laboratory control standard—a standard usually certified by an
outside agency that is used to measure the bias in a procedure.
For certain constituents and matrices, use National Institute of
Standards and Technology (NIST) or other national or inter-
national traceable sources (Standard Reference Materials),
when available.
Mean—the arithmetic average (the sum of measurements divided
by the number of items being summed) of a data set.
Median—the middle value (odd count) or mean of the two middle
values (even count) of a data set.
Mode—the most frequent value in a data set.
Percentile—a value between 1 and 100 that indicates what percent-
age of the data set is below the expressed value.
Precision (usually expressed as standard deviation)—a measure of
the degree of agreement among replicate analyses of a sample.
INTRODUCTION (1010)/Glossary
4
INTRODUCTION (1010)/Glossary
Quality assessment—procedure for determining the quality of
laboratory measurements via data from internal and external
quality control measures.
Quality assurance—a definitive plan for laboratory operations that
specifies the measures used to produce data with known precision
and bias.
Quality control—set of measures used during an analytical
method to ensure that the process is within specified control
parameters.
Random error—the deviation in any step in an analytical
procedure that can be treated by standard statistical tech-
niques. Random error is a major component of measure-
ment error and uncertainty.
Range—the difference of the largest and smallest values in a data
set.
Replicate—repeated operation during an analytical procedure.
Two or more analyses for the same constituent in an extract of
one sample constitute replicate extract analyses.
Spike—see fortification.
Surrogate standard—a pure compound added to a sample in the
laboratory just before processing so a method’s overall effi-
ciency can be determined.
Type I error (also called alpha error)—the probability of deter-
mining that a constituent is present when it actually is absent.
Type II error (also called beta error)—the probability of not
detecting a constituent that actually is present.
1010 D. Dilution/Concentration Operations
1. Adjusting Solution Volume
Analysts frequently must dilute or concentrate the amount of
analyte in a standard or sample aliquot to within a range suitable
for the analytical method so analysis can be performed with
specified accuracy. The following equations enable analysts to
compute the concentration of a diluted or concentrated aliquot
based on the original aliquot concentration and an appropriate
factor or fractional constant. (A factor in this context is the ratio
of final adjusted volume to original volume.) They also can
compute the concentration of adjusted aliquot volume based on
the original aliquot volume.
Concentration of diluted aliquot 	
original aliquot concentration � dilution fraction
Concentration of original aliquot 	
diluted aliquot concentration � dilution factor
Concentration of concentrated aliquot 	
original aliquot concentration � concentration factor
Concentration of original aliquot 	
concentrated aliquot concentration � concentration fraction
where:
Dilution fraction 	 original volume/adjusted volume,
Dilution factor 	 adjusted volume/original volume,
Concentration factor 	 original volume/adjusted volume, and
Concentration fraction 	 adjusted volume/original volume.
2. Types of Dilutions
Several types of dilutions are used in Standard Methods pro-
cedures. Two of the most common volumetric techniques critical
to analytical chemistry results are:
a. Volumetric addition [a/(a 
 b)]. This method typically is
used to dilute microbiological samples and prepare reagents
from concentrated reagents. It assumes that volumes a and b are
additive (i.e., when a is combined with b in one container, the
total volume will equal a 
 b, which is not always the case).
Most aqueous-solution volumes are additive, but alcoholic solu-
tions or concentrated acid may be only partially volumetrically
additive, so be aware of potential problems when combining
nonaqueous solutions with aqueous diluents.
b. Volumetric dilution to a measured volume (a/c). This
method is used to dilute an aliquot to a given volume via a pipet
and volumetric flask. It is the most accurate means of dilution,
but when fortifying sample matrices, some error can be intro-
duced if a regular Class A volumetric flask is used. The error will
be proportional to the volumes of both spiking solution and flask.
For the most accurate work, measure the unfortified sample
aliquot in a 100-mL Cassia Class A volumetric flask to the
100-mL mark (0.0 on the flask neck*), and then pipet the volume
of fortifying solution. Mix the solution and note the graduated
volume on the neck of the flask. The fortified solution’s true
volume is equal to 100 mL 
 graduated volume over 100 mL.
The true total volume is necessary when computing the dilution
factor for the percent recovery of fortified analyte (LFM) in
Sections 1020B.12e and 4020B.3a to obtain the most accurate
analytical estimate of recovery.
Dilution factors for multiple volumetric dilutions are calcu-
lated as the product of the individual dilutions. Generally, serial
dilution is preferred when making dilutions of more than two or
three orders of magnitude. Avoid trying to pipet quantities of less
than 1.0 mL into large volumes (e.g., �1.0 mL into 100 or 1000
mL) to avoid large relative error propagation.
Some biological test methods (e.g., BOD or toxicity testing) may
include dilution techniques that do not strictly conform to the pre-
ceding descriptions. For example, such techniques may use
continuous-flow dilutors and dilutions prepared directly in test
equipment, where volumes are not necessarily prepared via Class A
volumetric equipment. Follow the method-specific dilution directions.
3. Bibliography
NIEMELA, S.I. 2003. Uncertainty of Quantitative Determinations Derived
by Cultivation of Microorganisms, Publication J4/2003 MIKES.
Metrologia, Helsinki, Finland.
* Pyrex, or equivalent.
INTRODUCTION (1010)/Dilution/Concentration Operations
5
INTRODUCTION (1010)/Dilution/Concentration Operations
1020 QUALITY ASSURANCE*
1020 A. Introduction
This section applies primarily to chemical and radiochemical
analyses. See Sections 8020 and 9020 for quality assurance and
control for toxicity assays and microbiological analyses.
Quality assurance (QA) is a laboratory operations program
that specifies the measures required to produce defensible data
with known precision and accuracy. This program is defined in
a QA manual, written procedures, work instructions, and re-
cords. The manual should include a policy that defines the
statistical level of confidence used to express
data precision and
bias, as well as method detection levels (MDLs) and reporting
limits. The overall system includes all QA policies and quality
control (QC) processes needed to demonstrate the laboratory’s
competence and to ensure and document the quality of its ana-
lytical data. Quality systems are essential for laboratories seek-
ing accreditation under state or federal laboratory certification
programs.
QA includes both QC (1020B) and quality assessment
(1020C). For information on evaluating data quality, see Section
1030.
1. Quality Assurance Plan
Establish a QA program and prepare a QA manual or plan.
The QA manual and associated documents include the following
items1–5: cover sheet with approval signatures; quality policy
statement; organizational structure; staff responsibilities; analyst
training and performance requirements; tests performed by the
laboratory; procedures for handling and receiving samples; sam-
ple control and documentation procedures; procedures for
achieving traceable measurements; major equipment, instrumen-
tation, and reference measurement standards used; standard op-
erating procedures (SOPs) for each analytical method; proce-
dures for generating, approving, and controlling policies and
procedures; procedures for procuring reference materials and
supplies; procedures for procuring subcontractors’ services; in-
ternal QC activities; procedures for calibrating, verifying, and
maintaining instrumentation and equipment; data-verification
practices, including inter-laboratory comparison and proficien-
cy-testing programs; procedures for feedback and corrective
actions whenever testing discrepancies are detected; procedures
for permitted exceptions to documented policies; procedures for
system and performance audits and reviews; procedures for
assessing data precision and accuracy and determining MDLs;
procedures for data reduction, validation, and reporting; proce-
dures for archiving records; procedures and systems for control-
ling the testing environment; and procedures for dealing with
complaints from data users. Also, define the responsibility for,
and frequency of, management review and updates to the QA
manual and associated documents.
On the title page, include approval signatures, revision num-
bers, and a statement that the manual has been reviewed and
determined to be appropriate for the scope, volume, and range of
testing activities at the laboratory,2,3 as well as an indication that
management has committed to ensuring that the quality system
defined in the QA manual is implemented and followed at all
times.
The QA manual also should clearly specify and document the
managerial responsibility, authority, quality goals, objectives,
and commitment to quality. Write the manual so it is clearly
understood and ensures that all laboratory personnel understand
their roles and responsibilities.
Implement and follow sample-tracking procedures, including
legal chain-of-custody procedures (as required by data users) to
ensure that chain of custody is maintained and documented for
each sample. Institute procedures to trace a sample and its
derivatives through all steps from collection through analysis,
reporting of final results, and sample disposal. Routinely practice
adequate and complete documentation, which is critical to ensure
that data are defensible, to meet laboratory accreditation/certifi-
cation requirements, and to ensure that all tests and samples are
fully traceable.
Standard operating procedures describe the analytical meth-
ods to be used in the laboratory in sufficient detail that a
competent analyst unfamiliar with the method can conduct a
reliable review and/or obtain acceptable results. SOPs should
include, where applicable, the following items2–4: title of refer-
enced, consensus test method; sample matrix or matrices; MDL;
scope and application; summary of SOP; definitions; interfer-
ences; safety considerations; waste management; apparatus,
equipment, and supplies; reagents and standards; sample collec-
tion, preservation, shipment, and storage requirements; specific
QC practices, frequency, acceptance criteria, and required cor-
rective action if acceptance criteria are not met; calibration and
standardization; details on the actual test procedure, including
sample preparation; calculations; qualifications and performance
requirements for analysts (including number and type of analy-
ses); data assessment/data management; references; and any
tables, flowcharts, and validation or method performance data.
At a minimum, validate a new SOP before use by first deter-
mining the MDL and performing an initial demonstration of
capability using relevant regulatory guidelines. (NOTE: MDL
does not apply to biological, microbiological, and radiological
tests.)
Use and document preventive maintenance procedures for
instrumentation and equipment. An effective preventive mainte-
nance program will reduce instrument malfunctions, maintain
more consistent calibration, be cost-effective, and reduce down-
time. In the QA manual or appropriate SOP, include measure-
ment traceability to National Institute of Standards and Technol-
ogy (NIST) standard reference materials (SRMs) or commer-
* Reviewed by Standard Methods Committee, 2011.
Joint Task Group: Michael F. Delaney (chair), Clifford G. Annis, Jr., Daniel F.
Bender, George T. Bowman, Nilda B. Cox, Donald G. Davidson, Kenneth E.
Osborn, William R. Ray, Kailash C. Srivastava, David W. Tucker.
1
cially available reference materials certified traceable to
international or NIST SRMs to establish the integrity of the
laboratory calibration and measurement program. Formulate
document-control procedures, which are essential to data defen-
sibility, to cover the entire process: document generation, ap-
proval, distribution, storage, recall, archiving, and disposal.
Maintain logbooks for each test or procedure performed, with
complete documentation on preparation and analysis of each
sample, including sample identification, associated standards and
QC samples, method reference, date/time of preparation/analy-
sis, analyst, weights and volumes used, results obtained, and any
problems encountered. Keep logbooks that document mainte-
nance and calibration for each instrument or piece of equipment.
Calibration procedures, corrective actions, internal QC activities,
performance audits, and data assessments for precision and ac-
curacy (bias) are discussed in 1020B and C.
Data reduction, validation, and reporting are the final steps in
the data-generation process. The data obtained from an analytical
instrument must first be subjected to the data-reduction processes
described in the applicable SOP before the final result can be
obtained. In the QA manual or SOP, specify calculations and any
correction factors, as well as the steps to be followed when
generating the sample result. Also, specify all the data-validation
steps to be followed before the final result is made available.
Report results in standard units of mass, volume, or concentra-
tion, as specified in the method or SOP or as required by
regulators or clients. Report results below the minimum quanti-
tation level (MQL) or MDL in accordance with the procedure
prescribed in the SOP, regulatory requirements, or general lab-
oratory policy. The MQL is the lowest level that can be quan-
titated accurately.
Ideally, include a statement of uncertainty with each result.
See references and bibliography for other useful information and
guidance on establishing a QA program and developing an
effective QA manual.
2. References
1. U.S. ENVIRONMENTAL PROTECTION AGENCY. 2002. Guidance for Qual-
ity Assurance Plans (QA-G-5), EPA/240/R-02/009. U.S. Environ-
mental Protection Agency, Off. Environmental Information, Wash-
ington, D.C.
2. INTERNATIONAL ORGANIZATION for STANDARDIZATION. 2005. General
Requirements
for the Competence of Testing and Calibration Lab-
oratories, ISO/EIC/EN 17025. International Org. for Standardiza-
tion, Geneva, Switzerland.
3. U.S. ENVIRONMENTAL PROTECTION AGENCY. 2007. Guidance for the
Preparation of Standard Operating Procedures (SOPs) for Quality-
Related Documents, EPA/600/B-07/001 (QA/G-6). U.S. Environ-
mental Protection Agency, Washington, D.C.
4. U.S. ENVIRONMENTAL PROTECTION AGENCY. 2005. Manual for the
Certification of Laboratories Analyzing Drinking Water, 5th Edi-
tion, EPA-815-R-05-004. U.S. Environmental Protection Agency,
Washington, D.C.
5. U.S. ENVIRONMENTAL PROTECTION AGENCY. 2008. Supplement to 5th
Edition of Manual for Certification of Laboratories Analyzing
Drinking Water, EPA 815-F-08-006. U.S. Environmental Protection
Agency, Off. Water, Off. Groundwater and Drinking Water, Tech-
nical Support Center, Cincinnati, Ohio.
3. Bibliography
DELFINO, J.J. 1977. Quality assurance in water and wastewater analysis
laboratories. Water Sew. Works 124:79.
INHORN, S.L., ed. 1978. Quality Assurance Practices for Health Labora-
tories. American Public Health Assoc., Washington, D.C.
STANLEY, T.W. & S.S. VERNER. 1983. Interim Guidelines and Specifi-
cations for Preparing Quality Assurance Project Plans, EPA-600/4-
83-004. U.S. Environmental Protection Agency, Washington, D.C.
INTERNATIONAL ORGANIZATION for STANDARDIZATION. 2005. General Re-
quirements for the Competence of Testing and Calibration Labora-
tories, ISO/IEC 17025. International Org. for Standardization, Ge-
neva, Switzerland.
U.S. ENVIRONMENTAL PROTECTION AGENCY. 1994. National Environmen-
tal Laboratory Accreditation Conference (NELAC) Notice of Con-
ference and Availability of Standards. Fed. Reg. 59(231).
U.S. ENVIRONMENTAL PROTECTION AGENCY. 1995. Good Automated Lab-
oratory Practices. U.S. Environmental Protection Agency, Research
Triangle Park, N.C.
AMERICAN ASSOCIATION for LABORATORY ACCREDITATION. 1996. General
Requirements for Accreditation. American Assoc. Laboratory Ac-
creditation (A2LA), Gaithersburg, Md.
1020 B. Quality Control
Include in each analytical method or SOP the minimum re-
quired QC for each analysis. A good QC program consists of at
least the following elements, as applicable: initial demonstration
of capability (IDC), ongoing demonstration of capability, MDL
determination, reagent blank (also referred to as method blank),
laboratory-fortified blank (LFB) (also referred to as blank spike),
laboratory-fortified matrix (also referred to as matrix spike),
laboratory-fortified matrix duplicate (also referred to as matrix
spike duplicate) or duplicate sample, internal standard, surrogate
standard (for organic analysis) or tracer (for radiochemistry),
calibration, control charts, and corrective action, frequency of
QC indicators, QC acceptance criteria, and definitions of a batch.
Sections 1010 and 1030 describe calculations for evaluating
data quality.
1. Initial Demonstration of Capability
Each analyst in the laboratory should conduct an IDC at least
once before analyzing any sample to demonstrate proficiency in
performing the method and obtaining acceptable results for each
analyte. The IDC also is used to demonstrate that the laborato-
ry’s modifications to a method will produce results as precise
and accurate as those produced by the reference method. As a
minimum, include a reagent blank and at least four LFBs at a
concentration between 10 times the MDL and the midpoint of
the calibration curve (or other level specified in the method). Run
the IDC after analyzing all required calibration standards. Ensure
that the reagent blank does not contain any analyte of interest at
a concentration greater than half the MQL (or other level spec-
QUALITY ASSURANCE (1020)/Quality Control
2
QUALITY ASSURANCE (1020)/Quality Control
ified in the method). Ensure that precision and accuracy (percent
recovery) calculated for LFBs are within the acceptance criteria
listed in the method of choice or generated by the laboratory (if
there are no established mandatory criteria).
To establish laboratory-generated accuracy and precision lim-
its, calculate the upper and lower control limits from the mean
and standard deviation of percent recovery for at least 20 data
points:
Upper control limit � Mean � 3(Standard deviation)
Upper control limit � Mean � 3(Standard deviation)
Laboratory-generated acceptance criteria for the IDC (in the
absence of established mandatory criteria) generally would meet
industry-acceptable guidelines for percent recovery and percent
relative standard deviation (%RSD) criteria (e.g., 70 to 130%
recovery/20% RSD criteria). Another option is to obtain accep-
tance criteria from a proficiency testing (PT) provider on the
inter-laboratory PT studies and translate the data to percent
recovery limits per analyte and method of choice.
Also, verify that the method is sensitive enough to meet
measurement objectives for detection and quantitation by deter-
mining the lower limit of the operational range.
2. Operational Range
Before using a new method or instrument, determine its op-
erational (calibration) range (upper and lower limits). Use con-
centrations of standards for each analyte that provide increasing
instrument response (linear, weighted, or second-order). Labo-
ratories must define acceptance criteria for the operational range
in their QA plans.
3. Ongoing Demonstration of Capability
The ongoing demonstration of capability, sometimes called a
laboratory control sample, laboratory control standard, QC
check sample, or laboratory-fortified blank, is used to ensure that
the laboratory remains in control while samples are analyzed and
separates laboratory performance from method performance on
the sample matrix. For initial calibration, the calibration standard
must be verified by comparing it to a second-source calibration
standard solution. The laboratory control standard used for on-
going demonstration of capability generally can be either from
the same source as the initial calibration standard or from a
separate source. Some methods may require that both calibration
and spiking solutions be verified with a second (external) source.
When verifying the initial calibration control solution, its con-
centration must be within 10% of the value of the second source.
See ¶ 6 below for further details on the LFB. Analyze QC check
samples on at least a quarterly basis.
4. Method Detection Level Determination and Application
Before analyzing sample, determine the MDL for each analyte
of interest and method to be used. As a starting point for
selecting the concentration to use when determining the MDL,
use an estimate of five times the estimated true detection level.
Start by adding the known amount of constituent to reagent
water or sample matrix to achieve the desired concentration.
Ideally, prepare and analyze at least seven portions of this
solution over a 3-d period to ensure that the MDL determination
is more representative of routine measurements as performed in
the laboratory. The replicate measurements should be in the
range of one to five times the estimated MDL, and recoveries of
the known addition should be between 50 and 150%, with
%RSD values �20%. Calculate the estimated standard devia-
tion, s, of the 7 replicates, and from a table of one-sided t
distribution, select t for (7-1) � 6 degrees of freedom at the 99%
confidence level. This value, 3.14, is then multiplied by the
calculated estimate of standard deviation, s:
MDL� 3.14s
Ideally, use pooled data from several analysts rather than one
analyst (provided, obviously, that the laboratory routinely has
multiple analysts running a given test method) to estimate s.
The pooled estimate of �, which is defined here as Spooled, is
a weighted average of the individual analysts’ �. Spooled is
calculated from the deviations
from the mean of each analyst’s
data subset squared, which are then summed, divided by the
appropriate number of degrees of freedom, and the square root
determined. Using Spooled to calculate multiple-analyst standard
deviation allows each analyst’s error and bias to affect the final
result only as much as they have contributed to that result.1
Spooled�
��i�1
N1
�Xi � X1�2 � �
j�1
N2
�Xi � X2�2 � �
k�1
N3
�Xi � X3�2 � . . .
N1 � N2 � N3 . . .� Nt
�
1/2
Perform MDL determinations iteratively. If the calculated
MDL is not within a factor of l0 of the known addition, repeat
determinations at a more suitable concentration. Ideally, conduct
MDL determinations at least annually (or other specified fre-
quency) for each analyte, major matrix category, and method in
use at the laboratory. Perform or verify MDL determination for
each analyst and instrument, as well as whenever significant
modifications to the method’s instruments or operating condi-
tions also modify detection or chemistry. Include all sample-
preparation steps in the MDL determination.
Generally, apply the MDL to reporting sample results as
follows (unless there are regulatory or client constraints to the
contrary):
• Report results below the MDL as “not detected” (ND), LRL
(MRL, MQL, LOQ, etc.).
• Report results between the MDL and MQL with qualification
for the quantified value given.
• Report results above the MQL with a value and its associated
error.
5. Reagent Blank
A reagent blank (method blank) consists of reagent water (see
Section 1080) and all reagents (including preservatives) that
normally are in contact with a sample during the entire analytical
procedure. The reagent blank is used to determine whether and
QUALITY ASSURANCE (1020)/Quality Control
3
QUALITY ASSURANCE (1020)/Quality Control
how much reagents and the preparative analytical steps contrib-
ute to measurement uncertainty. As a minimum, include one
reagent blank with each sample set (batch) or on a 5% basis,
whichever is more frequent. Analyze a blank after the daily
calibration standard and after highly contaminated samples if
carryover is suspected. Evaluate reagent blank results for con-
tamination. If unacceptable contamination is present in the re-
agent blank, identify and eliminate the source. Typically, sample
results are suspect if analyte(s) in the reagent blank are greater
than the MQL. Samples analyzed with a contaminated blank
must be re-prepared and re-analyzed. Refer to the method of
choice for specific reagent-blank acceptance criteria. General
guidelines for qualifying sample results with regard to reagent
blank quality are as follows:
• If the reagent blank is less than the MDL and sample results
are greater than the MQL, then no qualification is required.
• If the reagent blank is greater than the MDL but less than the
MQL and sample results are greater than the MQL, then qualify
the results to indicate that analyte was detected in the reagent
blank.
• If the reagent blank is greater than the MQL, further correc-
tive action and qualification is required.
6. Laboratory-Fortified Blank/Laboratory Control Standard
A laboratory-fortified blank [laboratory control standard
(LCS)] is a reagent water sample (with associated preservatives)
to which a known concentration of the analyte(s) of interest has
been added. An LFB is used to evaluate laboratory performance
and analyte recovery in a blank matrix. Its concentration should
be high enough to be measured precisely, but not high enough to
be irrelevant to measured environmental concentrations. Prefer-
ably, rotate LFB concentrations to cover different parts of the
calibration range. As a minimum, include one LFB with each
sample set (batch) or on a 5% basis, whichever is more frequent.
(The definition of a batch is typically method-specific.) Process
the LFB through all sample preparation and analysis steps. Use
an added concentration of at least 10 times the MDL, less than
or equal to the midpoint of the calibration curve, or level spec-
ified in the method. Ideally, the LFB concentration should be less
than the MCL (if the contaminant has an MCL). Depending on
the method’s specific requirements, prepare the addition solution
from either the same reference source used for calibration, or
from an independent source. Evaluate the LFB for percent re-
covery of the added analytes by comparing results to method-
specified limits, control charts, or other approved criteria. If LFB
results are out of control, take corrective action, including re-
preparation and re-analysis of associated samples if required.
Use LFB results to evaluate batch performance, calculate recov-
ery limits, and plot control charts (see ¶ 13 below).
7. Laboratory-Fortified Matrix
A laboratory-fortified matrix (LFM) is an additional portion of
a sample to which a known amount of the analyte(s) of interest
is added before sample preparation. Some analytes are not ap-
propriate for LFM analysis; see tables in Sections 2020, 4020,
5020, 6020, and specific methods for guidance on when an LFM
is relevant.
The LFM is used to evaluate analyte recovery in a sample
matrix. If an LFM is feasible and the method does not specify
LFM frequency requirements, then include at least one LFM
with each sample set (batch) or on a 5% basis, whichever is more
frequent. Add a concentration that is at least 10 times the MRL,
less than or equal to the midpoint of the calibration curve, or
method-specified level to the selected sample(s). Preferably use
the same concentration as for the LFB to allow analysts to
separate the matrix’s effect from laboratory performance. Pre-
pare the LFM from the same reference source used for the
LFB/LCS. Make the addition such that sample background lev-
els do not adversely affect recovery (preferably adjust LFM
concentrations if the known sample is more than five times the
background level). For example, if the sample contains the
analyte of interest, then add approximately as much analyte to
the LFM sample as the concentration found in the known sam-
ple. Evaluate the results obtained for LFMs for accuracy or
percent recovery. If LFM results are out of control, then take
corrective action to rectify the matrix effect, use another method,
use the method of standard addition, or flag the data if reported.
Refer to the method of choice for specific acceptance criteria for
LFMs until the laboratory develops statistically valid, laborato-
ry-specific performance criteria. Base sample batch acceptance
on results of LFB analyses rather than LFMs alone, because the
LFM sample matrix may interfere with method performance.
8. Duplicate Sample/Laboratory-Fortified Matrix Duplicate
Duplicate samples are analyzed randomly to assess precision
on an ongoing basis. If an analyte is rarely detected in a matrix
type, use an LFM duplicate. An LFM duplicate is a second
portion of the sample described in ¶ 6 above to which a known
amount of the analyte(s) of interest is added before sample
preparation. If sufficient sample volume is collected, this second
portion of sample is added and processed in the same way as the
LFM. If there is not enough sample for an LFM duplicate, then
use a portion of an alternate sample (duplicate) to gather data on
precision. As a minimum, include one duplicate sample or one
LFM duplicate with each sample set (batch) or on a 5% basis,
whichever is more frequent, and process it independently
through the entire sample preparation and analysis. Evaluate
LFM duplicate results for precision and accuracy (precision
alone for duplicate samples). If LFM duplicate results are out of
control, then take corrective action to rectify the matrix effect,
use another method, use the method of standard addition, or flag
the data if reported. If duplicate results are out of control, then
re-prepare and re-analyze the sample