J Anal Chem 2001 56 3 200-213 revisão CG

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Journal of Analytical Chemistry, Vol. 56, No. 3, 2001, pp. 200–213. Translated from Zhurnal Analiticheskoi Khimii, Vol. 56, No. 3, 2001, pp. 231–245.
Original Russian Text Copyright © 2001 by Ya. Yashin, A. Yashin.
 
Earlier analogous works deal with the period 1985–
1991. Unlike previous works, in this work we addition-
ally determined the fractions of publications on the
most important compounds and mixtures within 1980–
1998. Current trends in instrument making in gas chro-
matography are considered in more detail; references
are given to the most important books and reviews pub-
lished during this period. For the first time, the data is
presented on the total number of publications on the
main methods during the whole period of the develop-
ment of chromatography.
The total of obtained data made it possible to reveal
topical directions of the development of the theory,
fields of application, and instrumentation of gas chro-
matograph. This information will be useful for plan-
ning new theoretical and applied works and for the pre-
diction of new developments in the field of gas-chro-
matographic instrument making.
The distribution of publications over different chro-
matography methods was taken from bibliographic
indices published in 
 
J. Chromatogr.
 
, Bibliography Sec-
tion in 1981–1998.
Table 1 for the first time presents the data on the
total number of publications on main chromatography
methods. The data on publications in 1944–1966 were
taken from [3]; the other were taken from bibliographic
indices of articles published in 1966–1998.
DISTRIBUTION OF PUBLICATIONS 
OVER DIFFERENT GAS CHROMATOGRAPHY 
METHODS
Table 2 presents the distribution of publications over
different gas chromatography methods in 1985–1998.
The largest number of publications deal with open-tube
gas chromatography; these publications comprise
20
 
−
 
25% (from 400 to 600 per year). Up to 70–80% of
gas chromatography implementations employ open
tubular columns; these columns are used nearly in all
works on gas chromatography–mass spectrometry. The
scientometric analysis of the data on the development
of open-tube gas chromatography was presented by
Berezkin 
 
et al.
 
 [4–6]. The number of publications on
supercritical fluid chromatography decreases begin-
ning from 1993 (the largest number of works were pub-
lished in 1989–1992). Guiochon analyzed the develop-
ment of supercritical fluid chromatography (SFC) [7]
and compared it with Cinderella: “Unlike Cinderella,
SFC was invited three times to the ball, never made it,
and probably won’t dance.” However, supercritical
fluid chromatography has occupied a particular niche
between gas and liquid chromatography [8]. The posi-
tion of pyrolysis gas chromatography remains stable
primarily because of the combination of pyrolysis with
open tubular columns and a mass spectrometer as the
detector. A voluminous review (534 references) was
published on pyrolysis gas chromatography of syn-
thetic polymers [9]. In this combination, it was possible
to decipher the major part of information from pyro-
grams. The level of publications on multidimensional
chromatography is retained as well. Several reviews
and books were devoted to this technique [10–13].
Along with the combination gas chromatography–gas
chromatography, the combination liquid chromatogra-
phy–gas chromatography also received wide accep-
tance. Reversed gas chromatography is rather widely
used for studying the surface chemistry of solids
(adsorbents, catalysts, and polymer materials), in par-
ticular, the degree of oxidation, acid–base properties of
a surface using special test mixtures, the degree of the
deactivation of the surface of silica gel, the modifica-
tion of pigments with TiO
 
2
 
, the characterization of the
surface of cellulose, the estimation of the properties of
films formed by organic compounds at the surface of
adsorbents [14, 15], etc. Very few publications deal
with reaction, preparative, and industrial chromatogra-
phy. About ten works per year are published on
stopped-flow and reversed-flow gas chromatography.
This method is used for physicochemical measure-
ments.
Among new methods, high-speed [16, 17] and high-
temperature [18, 19] gas chromatography must be
emphasized.
 
Current Trends in Gas Chromatography Methods 
and Instrumentation: A Scientometric Study
 
Ya. I. Yashin and A. Ya. Yashin
 
NPO Khimavtomatika, Sel’skokhozyaistvennaya ul. 12-A, Moscow, 129226 Russia
 
Received April 18, 2000; in final form, August 2, 2000
 
Abstract
 
—Fractions of publications dealing with different problems of gas chromatography were determined,
and, based on this data, trends were revealed in particular fields of gas chromatography within 1992–1999.
 
REVIEWS
 
JOURNAL OF ANALYTICAL CHEMISTRY
 
 
 
Vol. 56
 
 
 
No. 3
 
 
 
2001
 
CURRENT TRENDS IN GAS CHROMATOGRAPHY METHODS 201
 
High-speed open-tube gas chromatography.
 
 Cur-
rently, this technique is being actively developed by
Cramers 
 
et al.
 
 [17] and some groups in Russia. How-
ever, high-speed chromatography is rarely used for rou-
tine work because of the absence of appropriate injec-
tion devices, detectors, and columns.
The main techniques for accelerating analysis are
the use of columns with a small inner diameter, small
length, and liquid phase films of small thickness as well
as the use of high flow rates of the carrier gas and high
rates of temperature programming. New instruments
providing temperature programming of columns with
rates up to 1200 K/min have been developed. For rapid
programming, an open tubular column is placed in a
metal tube, which is heated by passing current. The use
of high-speed chromatography methods provides a
decrease in the time of separation by a factor of 10; the
EZFlash method decreases the time of analysis by a
factor of 50.
 
High-temperature gas chromatography.
 
 The
development of new methods for the synthesis of sta-
tionary phases and the sophistication of processes for
column preparation expanded the boundaries of the
analysis of high-boiling compounds up to compounds
with molecular masses up to 600 D. Some nonpolar and
weakly polar stationary phases are workable up to
400
 
−
 
480
 
°
 
C and can be used for the analysis of hydro-
carbons up to C
 
100
 
 (or even C
 
120
 
) as well as lipids, trig-
lycerides, oligosaccharides, industrial resins, polyglyc-
erols, cyclodextrins, and porphyrins.
High-temperature gas chromatography finds its use
in organic geochemistry (the simulated distillation and
analysis of geoporphyrins, biomarkers, etc.), food
chemistry (the determination of triglycerides in oils and
fats and analysis of oligosaccharides), the chemistry of
natural products (analysis of flavonoids, rotenoids, and
vegetable extracts), environmental pollution control
(analysis of high-boiling polycyclic aromatic hydrocar-
bons), archeology (analysis of pigments, binders, res-
ins, and painting pasts), the chemistry of polymers
(study of oligomers), and analysis of some industrial
products (the quality control of nonionic detergents).
PUBLICATIONS ON GENERAL PROBLEMS 
OF THEORY AND INSTRUMENTATION
 
Books and reviews on gas chromatography.
 
 From
40 to 130 reviews on gas chromatography are published
yearly. The majority of these reviews are devoted to
applications of gas chromatography in different fields;
the number of reviews dealing with general problems
and instrumentation is smaller. The largest number of
reviews on gas chromatography were published in
1985–1992 (Table 3).
In recent years, several books have been published
on the fundamentals of gas chromatography [20–22],
 
Table 1. 
 
Total number of publications on different chromatography methods
Method
Years
1952–
1961
1962–
1966
1967–
1971
1972–
1976
1977–
1981
1982–
1986
1987–
1991
1992–
1998 Total
Liquid column chromatography– – 4535 8705 13056 19187 30373 37144 113000
Gas chromatography 4365 4992 6212 6541 5764 11106 13029 15380 66000
Planar types of chromatography 12000* 9430 9775 8080 7323 6011 6348 6533 65500
Electrophoresis – – 1882 6566 6240 6576 11306 19430 52000
Total 296500
 
* From 1944 to 1960.
 
Table 2. 
 
Number of publications on different gas chromatography methods (1985–1998, 
 
J. Chromatogr
 
., Bibliography section)
Gas chromatography 
methods 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998
Open-tube 625 581 531 443 408 420 412 432 440 473 430 566 447 461
Supercritical 9 120 153 144 256 266 210 228 186 150 138 80 121 132
Pyrolysis 81 87 100 101 91 58 50 48 82 75 69 58 53 52
Multidimensional 6 37 23 27 25 44 42 32 18 34 37 28 22 22
Reaction 20 20 27 27 17 25 8 15 1 – – 3 2 5
Reversed 10 28 26 39 52 45 33 46 53 42 7 29 34 24
Preparative 3 1 8 20 7 4 3 4 – 10 11 6 4 2
Industrial – – – – 10 10 18 2 – – – 10 7 7
 
202
 
JOURNAL OF ANALYTICAL CHEMISTRY
 
 
 
Vol. 56
 
 
 
No. 3
 
 
 
2001
 
YA.I. YASHIN, A.YA. YASHIN
 
the fundamentals of supercritical fluid chromatography
on packed columns [23], environmental pollution con-
trol and food analysis [24, 25], the theory and practice
of static head-space analysis [26], gas chromatogra-
phy–mass spectrometry (practical user’s guide) [27],
and food analysis by chromatography and capillary
electrophoresis [28].
 
Theoretical and methodological problems.
 
 The
main theoretical problems that were discussed in recent
publications are the study of the relationship between
the molecular structure of compounds and their reten-
tion on different sorbents [29], new classifications of
liquid phases in polarity [30, 31], mathematical simula-
tion, the handling of the problems of artificial intelli-
gence [32] and multiple-choice mathematical models
[33], the development of the unified retention theory for
gas, liquid, and supercritical fluid chromatography
[34], different types of complexation and molecular
recognition gas chromatography in the separation of
enantiomers [35], the effect of the nature of the carrier
gas in open-tube chromatography [36], the mutual cor-
relation of gas-chromatographic indices of different
series [37], and the combination of calculated and
experimental values (randomization) of retention indi-
ces on Porapak Q [38]. A new gas–liquid chromatogra-
phy method was proposed [39]. A program for main-
taining constant retention time on changing columns in
a Hewlett-Packard chromatograph was published [40].
 
General problems.
 
 Reviews of general character
deal with main fields of gas chromatography [41], the
development of gas chromatography “from the Nean-
derthal times to the present days” [42], the state and
prospects of the development of gas chromatography
[43], the 90th anniversary of chromatography [44],
40 years of gas-chromatography instrument making [45],
chromatographic nomenclature published on behalf of
the International Union of Pure and Applied Chemistry
(IUPAC) [46], and chromatographic terms and defini-
tions published by the Scientific Council on Chroma-
tography [47]. We should emphasize the most general
reviews on gas chromatography that are published in
 
Analytical Chemistry
 
 every two years [48–50]. In
recent years, a drastic increase was observed in the
number of publications on gas chromatography by Chi-
nese researchers both in international journals and in
Chinese scientific periodicals.
 
Physicochemical measurements using gas chro-
matography. Thermodynamics of retention param-
eters.
 
 In this section, we first note a large review on
studies of diffusion, adsorption, and catalysis using gas
chromatography [51], next, many publications on the
use of reversed gas chromatography for studying the
chemical nature of the surface of solids (polymers,
adsorbents, catalysts, and materials) and for examining
the surface of adsorbents after their adsorptive or chem-
ical modification. Dozens of articles were published on
reversed gas chromatography and studies of the surface
of silica gel coated with films of stationary phases,
porous polymers of different nature, titanium oxide,
cellulose, kaolinites, and phase transitions in some
materials. A large fraction of publications on this topic
deal with thermodynamic measurements using gas
 
Table 3. 
 
Number of publications on general problems of theory and apparatus in 1979–1998
Publications
Year
1979 1981 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1995 1996 1997 1998
Reviews and books 46 47 50 68 119 116 120 126 137 110 118 110 93 83 56 68
Theory fundamentals 13 10 12 16 32 23 10 20 34 17 16 5 27 21 26 19
General problems* – – – – – – – – – – – – – – – –
Thermodynamics
of retention parameters
16 25 24 28 31 39 49 31 26 28 22 32 19 31 26 24
Physicochemical mea-
surements
45 44 87 107 77 108 112 123 146 104 104 123 103 94 65 109
Relationship between
molecular structure and 
retention parameters
42 38 45 50 62 70 59 69 73 48 56 61 36 40 32 42
Sorbents 91 91 149 254 170 253 225 199 217 181 167 195 122 119 120 104
Combination of gas chro-
matography with other 
physicochemical methods
10 13 38 107 207 258 169 136 169 103 111 115 98 67 58 50
Detectors 56 105 107 145 166 148 119 103 118 96 110 122 79 82 64 68
Apparatus and additional 
devices
45 68 121 173 118 120 131 129 126 105 118 122 119 100 85 100
Automation and miniatur-
ization of apparatus
9 22 7 18 30 48 61 50 47 40 52 46 29 31 33 36
 
* No published papers.
 
JOURNAL OF ANALYTICAL CHEMISTRY
 
 
 
Vol. 56
 
 
 
No. 3
 
 
 
2001
 
CURRENT TRENDS IN GAS CHROMATOGRAPHY METHODS 203
 
chromatography: the determination of second virial
coefficients for hydrocarbons and chlorofluorohydro-
carbons under the conditions of gas-adsorption chro-
matography on a microporous carbon adsorbent; the
determination of adsorption coefficients, distribution
coefficients, and activity coefficients; the determination
of adsorption enthalpy, Gibbs solvation energies, and
donor–acceptor interaction enthalpy; the estimation of
dispersion interactions, equilibrium vapor pressure,
and the heat of vaporization; and many other measure-
ments.
 
Relationship between the molecular structure
and retention parameters.
 
 More than 70 articles were
published on this topic within the last two years. The
main aim of works on revealing the relationship
between retention and molecular structure is, on the
one hand, to predict retention parameters from the
molecular structure and, on the other hand, to predict
the chemical and biological activity of studied com-
pounds from retention parameters. Three directions are
considered for studying the relationship between the
structure of molecules and their retention: topological,
geometric, and electronic. Currently, all these works
employ semiempirical approaches. Rather many works
establish a correlation between retention parameters
and molecular properties, in particular, molar volume,
solubility parameters, electronic polarizabilities, dipole
moments, etc. The relationship between retention and
molecular structure was revealed for different classes of
compounds: polychlorinated biphenyls and naphthalenes,
alkylbenzenes, alkenes, polybrominated dibenzo-
 
p
 
-diox-
ins, etc.
A computer program was developed for the determina-
tion of retention parameters for a wide range of com-
pounds on columns with squalane as the stationary phase.
 
Columns and sorbents.
 
 Fused-silica columns pre-
dominate in open-tube chromatography; however,
interest is growing in metal columns with an inert inner
surface, particularly for high-temperature chromatog-
raphy [52]. There are publications on all types of open
tubular columns: WCOT columns with a film of a liquid
phase (most frequently, cross-linked and chemically
modified), SCOT columns with a film of a liquid phase
on a solid support deposited at the inner surface of a
capillary, PLOT columns with aporous adsorption
layer at the inner surface (commonly, these are porous
polymers of different nature, zeolites, silica gel, or alu-
mina), and CLOT columns with a layer of a carbon
adsorbent at the surface. Examples of the use of open
tubular columns with a diameter from 0.05–0.1 mm to
0.32, 0.53, and 0.75 mm were published. The thickness
of films of modified liquid phases varies from 0.1 to
5 
 
µ
 
m. Packed capillary columns also find use. General
problems of high-performance open-tube chromatogra-
phy were reviewed by Rudenko [53].
Interest is growing in polycapillary columns, in par-
ticular, for special rapid separations [54].
According to the data of reviews [55], dozens of
new open tubular columns (both general-purpose and
special) are offered yearly at the exhibition at the Pitts-
burg Conference. Nearly all general-purpose columns
have cross-linked or immobilized stationary phases.
These columns are more stable; their stationary phases
have lower volatility and higher upper temperature lim-
its. Many companies produce general-purpose columns
for trace analysis and for gas chromatography–mass
spectrometry. Columns with a 100% polymethylsilox-
ane or polymethylphenylsiloxane (5% of phenyl
groups) stationary phase are most frequently used for
these purposes. The retention of compounds on these
phases is primarily determined by dispersion interac-
tions, and the retention times are proportional to the
boiling temperatures of separated compounds [56].
Among special columns are columns for the separation
of petroleum products, in particular, for simulated dis-
tillation (gas chromatography is an official method
according to ASTM 2887); columns for PIONA (paraf-
fins, isoparaffins, olefins, naphthenes and aromatics)
analysis, chiral columns based on cyclodextrins (both
methylated and unmethylated); columns for environ-
mental pollution control; and PLOT columns, which
provide more rapid and efficient separation compared
to packed columns [57].
The frequency of use of different chromatography
methods in laboratories in 1995 and 1996 was revealed
by customer inquiry in Europe [58]. It was found that
open-tube gas chromatography was used most fre-
quently (75% in 1995 and 80% in 1996); packed col-
umns were used in 50% of laboratories. According to
the results of the same inquiry, the following liquid
phases are used most frequently: polymethylsiloxanes
(OV-1, OV-101, and SE-30), 73%; polymethylphenyl-
siloxanes (5% phenyl), 66%; polyethylene glycols,
53%; polymethylphenylsiloxanes (50% and 50%),
38%; and polymethylcyanopropylphenylsiloxanes (7%
cyan and 7% phenyl), 25%.
The possibilities of open tubular columns of very
large length (450 m 
 
×
 
 0.2 mm) have been described. For
this purpose, nine 50-m columns were connected in
series. Such a long column prepared for the analysis of
gasoline made it possible to separate 970 components
of standard gasoline. In this case, the efficiency of
1.3 million theoretical plates was attained [59]. Packed
glass columns with multicord for improving the perme-
ability of columns [60] and columns with direct heating
by a nickel–chromium wire passing through the col-
umn have been proposed.
Crown ethers, liquid crystals, cyclodextrins and
their derivatives, metal chelates, inorganic salts, chiral
polysiloxanes, and stationary phases based on organo-
metallic compounds are still of interest as liquid sta-
tionary phases. Carbon adsorbents are used in both
packed and open tubular columns.
 
204
 
JOURNAL OF ANALYTICAL CHEMISTRY
 
 
 
Vol. 56
 
 
 
No. 3
 
 
 
2001
 
YA.I. YASHIN, A.YA. YASHIN
 
COMBINATION OF GAS CHROMATOGRAPHY 
WITH OTHER CHROMATOGRAPHY METHODS 
AND OTHER PHYSICOCHEMICAL METHODS
The following combinations of gas chromatography
(GC) with other chromatography methods have been
described: GC–GC, GC–HPLC (high-performance liq-
uid chromatography), GC–SFC (supercritical fluid
chromatography), and GC–TLC (thin-layer chroma-
tography). Many works are published on the combina-
tion of gas chromatography with other methods. The
first place is occupied by different GC–MS (mass spec-
trometry) combinations: GC–MS-SIM (selected ion
monitoring), GC–CIMS (chemical-ionization mass
spectrometry), GC–EIMS (electron-impact mass spec-
trometry), GC–IMS (ion mobility spectrometry), GC–
ion-trap MS, and GC–MS with positive or negative ion
monitoring.
Publications on the combinations GC–FTIR (Fou-
rier-transform infrared spectrometry), GC–AAS
(atomic absorption spectrometry), GC–AED (atomic
emission detection), GC–NMR, GC–immunoassay,
and GC–olfactometry should be also mentioned. Ter-
nary combinations, in particular, GC–MS–FTIR, are
also described.
 
Detectors.
 
 During the last four years, the total num-
ber of publications on detectors has decreased. Twenty
six types of detectors have been described in the litera-
ture. Along with conventional detectors widely used in
stock-produced chromatographs (flame-ionization,
thermoionic, flame-photometric, electron-capture, pho-
toionization, and conductometric), there are publica-
tions on the use of other detectors including chemilu-
minescence, fluorescence, spectrophotometric, ultravi-
olet, electrochemical, mass-selective, acoustic, surface-
ionization, element-specific, plasma-emission, radioac-
tive, inductively-coupled plasma, helium ionization,
discharge ionization, etc.
Table 4 presents the data on the number of compa-
nies producing and selling different types of detectors
for gas chromatography.
The main companies producing gas chromato-
graphs equip their instruments with six or seven detec-
tors: flame-ionization, electron-capture, thermal-con-
ductivity, flame-photometric, thermoionic, photoion-
ization, and mass-spectrometric. The majority of these
detectors can work with both packed and open tubular
columns.
Special requirements for detectors in open-tube
chromatography are presented in [61].
 
Instruments and additional devices.
 
 Tables 5 and
6 present the data on the number of companies produc-
ing and selling gas chromatographs for different pur-
poses and additional equipment for gas chromato-
graphs.
From these tables, it is seen that the number of these
companies significantly varies with time. This is due to
the fact that many small companies go bankrupt and
new companies appear.
In [62], the yearly world sales of gas chromato-
graphs was estimated at about $1 billion. These sales
have not grown during the last three years unlike sales
of liquid chromatographs ($2.2 billion), which increase
at a rate of up to 5% yearly.
One of the main reasons for this retardation of the
growth of sales of gas chromatographs is that relatively
few design innovations were proposed for gas chro-
matographs during the last decade. As a result, custom-
ers are not stimulated to change old gas chromato-
graphs with new instruments. The highest rate of the
increase in sales of gas chromatographs was observed
 
Table 4. 
 
Number of companies selling detectors for gas chromatography (according to data from the Buyers Guide in
 
LC
 
−
 
GC Intern
 
., 1993–1997, no. 8 and the Directory in 
 
LC–GC Intern
 
., 1998–1999, no. 8)
Detectors
Year
1993 1994 1995 1996 1997 1998 1999
Flame-ionization 38 29 34 28 34 43 25
Electron-capture 29 20 24 21 28 37 19
Thermal-conductivity 28 23 27 23 27 33 20
Mass-spectrometric 25 35 29 24 39 49 32
Photoionization 20 20 20 20 26 31 18
Flame-photometric 27 22 19 14 25 36 17
Thermoionic (N- and P-selective) 18 13 15 14 18 24 12
Helium ionization 12 7 5 9 7 12 8
Hall electrolytic 16 13 12 10 12 16 10
Chemiluminescence 8 6 6 5 7 9 5
Infrared 8 5 5 3 7 9 3
Atomic-emission 2 2 3 2 3 6 3
 
JOURNAL OF ANALYTICAL CHEMISTRY
 
 
 
Vol. 56
 
 
 
No. 3
 
 
 
2001
 
CURRENT TRENDS IN GAS CHROMATOGRAPHY METHODS 205
 
Table 5. 
 
Number of companies selling different instruments for gas chromatography (according to data from the Buyers
Guide in 
 
LC–GC Intern
 
.,1993–1997, no. 8 and the Directory in 
 
LC–GC Intern
 
., 1998–1999, no. 8)
Chromatographs
and chromatographic systems
Year
1993 1994 1995 1996 1997 1998 1999
Analytical 47 37 35 31 40 57 35
Gas analyzers 33 24 25 18 24 44 27
Chromatograph–mass spectrometers 19 15 14 17 19 25 18
On-line analyzers 18 14 13 11 11 31 15
Multidimensional 11 12 8 12 15 20 11
Preparative 6 6 6 5 4 9 8
Industrial 5 6 8 5 12 19 12
GC + FTIR spectrometers 7 6 6 5 7 10 6
Radiochromatographs 5 6 8 2 3 5 3
 
Table 6. 
 
Number of companies selling components of gas-chromatographic systems, columns, and additional devices (accord-
ing to data from the Buyers Guide in 
 
LC–GC Intern
 
., 1993–1997, 1999, no. 8 and the Directory in 
 
LC–GC Intern
 
., 1998, no. 8)
Items
Year
1993 1994 1995 1996 1997 1998 1999
 
Components of gas-chromatographic systems
 
Systems for automatic sample injection 36 31 28 28 35 52 24
Sampling systems 39 25 26 24 30 31 23
Purge-and-trap units 32 26 34 31 34 45 20
Head-space analysis unit 29 21 22 22 26 28 19
Pyrolysers 17 16 17 17 19 22 8
Thermodesorbers 25 18 22 22 25 30 16
Gas flow controllers 50 40 37 32 27 38 35
GC–MS interface 17 17 13 16 14 18 9
GC–FTIR interface 10 8 5 5 7 9 2
LC–GC interface 5 4 3 3 6 10 3
 
Columns
 
Packed analytical 39 36 39 31 42 53 37
Micro packed 20 23 26 20 25 35 12
Packed preparative 21 18 15 11 19 26 11
Open tubular 39 37 40 35 48 61 36
Open tubular high-temperature 31 32 31 31 39 45 31
Open tubular chiral – 27 28 23 33 39 27
Open tubular, for pollution control 37 35 35 34 44 51 35
 
Additional devices
 
Hydrogen generators 39 29 29 28 42 43 25
Nitrogen generators 24 20 19 20 31 34 21
Ultrapure air generators 16 24 22 21 31 32 18
Gas purifiers 49 40 39 35 48 60 43
Syringes 47 48 38 34 67 40
 
in the 1980s and 1990s because the instruments were
modified to meet the demand of the market of gas chro-
matographs for environmental pollution control. The
same work [62] presents the technical characteristics
and complete equipment of the best models of most
prominent manufacturers in the world; these are
Hewlett-Packard, Perkin-Elmer, Varian, Thermo Quest,
Gow-Mac, SPI Instruments, Thermedics Detection (all
 
206
 
JOURNAL OF ANALYTICAL CHEMISTRY
 
 
 
Vol. 56
 
 
 
No. 3
 
 
 
2001
 
YA.I. YASHIN, A.YA. YASHIN
 
USA), Shimadzu (Japan), and Unicam Chromatogra-
phy (UK). The following modes are presented:
HP6890, Auto System XL, CP3800, Trace GC-2000,
series 816, 8610C, Flash-GC, GC-17A ver 3, and
ProGC. A brief analysis of these models is given below.
 
Injection ports.
 
 These models employ different
types of injection ports, in particular, systems for the
injection of samples into open tubular columns with
and without flow splitting, dosing valves for gases and
liquids, systems for the injection of samples into a cold
column, units for the injection of large volumes into
open tubular columns, a programmed temperature
vaporizer for removing the solvent, an injection port for
solid-phase extraction, and a pyrolysis injection unit.
Commonly, each instrument has a unit for the injection
of liquid samples into packed columns with a microsy-
ringe.
Six models are equipped with two injection units
simultaneously, one model has three injection units,
and one model has four injection units. For different
models, from three to seven sample injection units are
offered for sale.
 
Detection systems.
 
 Twenty-one types of detectors
(flame-ionization, thermal-conductivity, electron-cap-
ture, flame-photometric, photoionization, thermoionic,
atomic-emission, mass-selective, chemiluminescence
(sensitive to nitrogen and sulfur in organic compounds),
electrolytic-conductivity, discharge ionization, helium
ionization, nitrogen–phosphorus or thermoionic, emis-
sion, nitrogen-selective, pulsed-discharge, surface-ion-
ization, time-of-flight mass-spectrometric, thermoionic
specific (similar to thermoionic), and thermoionic
emission (specific for halogens)) are offered for differ-
ent models of chromatographs. One instrument is
equipped with two to four detectors simultaneously;
from six to nine detectors are offered in specifications
for different models. The first six of the above detectors
are supplied for nearly all models; six models can be
equipped with a mass-selective detector. The other
detectors are used only in one or two special-purpose
models.
 
Thermostat.
 
 The volumes of thermostats of chro-
matographs vary from 10 to 15 L (except for Thermo
Quest 8610C, USA with the volume of the thermostat
2.8 L). The working temperature range covers the
region from 
 
−
 
99 to 450
 
°
 
C; the initial temperature pro-
gramming rate is from 40 to 120 K/min. In the Flash-GC
instrument, the heating rate is as high as 1800 K/min.
The maximum number of heating steps is commonly
from three to seven, and in two models it is not limited.
 
Additional units.
 
 To expand their analytical possi-
bilities, chromatographic instruments can be equipped
with the following additional units: systems for auto-
matic sample injection (from 8 to 120 vessels), precon-
centration units (head space, purge and trap, thermode-
sorber, and solid-phase extraction unit), and systems
for the purification of gases (helium, hydrogen, etc.).
 
Software.
 
 All models are supplied with their own
software packages (TurboChrom (Perkin-Elmer),
Chem Station, Star Chromatography Workstation,
Chrom Quest, Chromatopack, Front Runner, etc.).
Requirements to the computer programs for chromato-
graphic data processing were presented in [63]. Retro-
spective assessment of chromatographic data process-
ing systems was given in reviews [64, 65].
 
Miniaturization of chromatographic apparatus.
 
Two recent trends in gas chromatography were clearly
expressed in publications within 1992–1999: decrease
in the time of separation, i.e., rapidity of analysis and
miniaturization of chromatographic apparatus [49, 50].
Examples of the use of conventional laboratory chro-
matographs for rapid separation and rapid separation
on columns with small diameter using special portable
chromatographs were published. New commercially
available instruments for high-speed chromatography
have small thermostats and systems for rapid heating of
columns. Gradient heating of the column makes it pos-
sible to separate 13 compounds within 3.5 s. However,
columns of small diameter require special methods for
sample injection.
Many portable high-speed chromatographs are used
for analysis at the place of sampling. A micro gas chro-
matograph with a thermal-conductivity detector pro-
vides the separation of a mixture of alkanes C
 
1
 
–C
 
4
 
 and
CO
 
2
 
 within 30 s. Other applications of instruments of
this kind in petroleum chemistry include the trace
determination of H
 
2
 
S and CO
 
2
 
 and rapid screening of
hydrocarbon components from gasoline to diesel fuel.
Portable high-speed chromatographs find use predomi-
nantly in environmental analysis. The last published
examples of their use in this field include the determi-
nation of residual pesticides in soil and agricultural
products; the analysis of air; the trace determination of
polychlorobiphenyls and aromatic and chlorinated
compounds in soil; and the determination benzene,
polyphosphonic acid esters, dimethyl sulfide, and car-
bon disulfide in air and freons in troposphere. A very
important present-day problem is the analysis of air
pollution in inhabited areas (flats and offices). The con-
centrations of some components (mercury, formalde-
hyde, etc.) indoors can be several times higher than in the
city atmosphere. Toluene, 
 
α
 
-pyrene, and 1,4-dichlo-
robenzene were determined indoors using a portable
chromatograph at a level below 1 mg/m
 
3
 
. Examples of
the trace determination of pesticides in blood plasma
and the analysis of thermally unstable steroids and
other drugs were described.
In addition to small size and weight, the power con-
sumption ofportable chromatograph is no higher than
100 W.
These portable instruments retain analytical charac-
teristics of stationary instruments and, thus, are suitable
for use not only in the field, but also in laboratories
because they consume lower power, occupy smaller
area on laboratory tables, etc. However, the next level
 
JOURNAL OF ANALYTICAL CHEMISTRY
 
 
 
Vol. 56
 
 
 
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2001
 
CURRENT TRENDS IN GAS CHROMATOGRAPHY METHODS 207
 
of miniaturization is the development of instruments on
chips based on silicon technology. Portable chromato-
graphs for multidimensional analysis, in particular, for
two-dimensional gas chromatography were described.
 
Main fields of application.
 
 Table 7 presents the
fields of application that were mentioned in biblio-
graphic indices of articles and for which the number of
publications is maximum.
 
Environmental pollution control.
 
 Articles on envi-
ronmental pollution control comprise the largest num-
ber of publications (250–300 articles per year, i.e.,
15
 
−
 
16% of the total number).
Within 1991–1998, more than 2000 articles and
reviews were published on the analysis of environmen-
tal pollution. The main test materials were water, air,
soil, precipitation, bottom sediments, etc. The largest
number of works deal with the analysis of air and water.
There are publications on the determination of the fol-
lowing pollutants: chlorinated hydrocarbons in air and
water, volatile aromatic hydrocarbons in air (in partic-
ular, benzene, toluene, ethylbenzene, and xylenes),
polynuclear aromatic hydrocarbons, polychlorobiphe-
nyls, dioxins, pesticides, phthalates, aldehydes, nitro-
samines, etc. Supertoxicants such as polychlorinated
dioxins and nitrosamines are determined at a level
10 ppt and lower. Several books have been published
on the environmental pollution analysis by gas chroma-
tography [24, 25, 66–68]. The most interesting reviews
deal with the determination of mutagenic amines in the
environment [69], phenol and its derivatives in water
[70], polychlorobiphenyls [71], and polynuclear aro-
matic hydrocarbons [72]; problems of the environmen-
tal pollution in some regions with toxic agents (war
gases) [73] and products of their detoxication.
The following reviews of general character were
published: the use of chromatography for the determi-
nation of environmental pollution in China [74], the use
of high-temperature chromatography [75], on-site
monitoring of organic pollutants using portable gas
chromatographs [76], and a general review on air pol-
lution [77].
When concentrations of pollutants are lower than
the detection limit, analysis is performed using differ-
ent preconcentration methods, such as head-space and
purge-and-trap methods; liquid, solid-phase, and super-
critical extractions; membrane extraction; and solid-
phase microextraction. Currently, the largest number of
works are published on solid-phase extraction. In par-
ticular, reviews were published on the following topics:
new techniques of solid-phase extraction [78], current
research and prospects of sample preparation by solid-
phase extraction [79]; the automation of solid-phase
extraction [80], reasons for the predominance of solid-
phase extraction [81], the combination of solid-phase
extraction with open tubular columns [82], a review of
all problems of solid-phase extraction and microextrac-
tion [83], and recent advances in this field [84].
General problems of sample preparation for gas
chromatography were considered in [85], the results of
comparative studies of sample preparation in Europe
and the United States were discussed in [86], and the
use of membranes in sample preparation was described
in [87].
Reviews were published on purge-and-trap analysis
[88], head-space analysis [89], and supercritical fluid
extraction [90].
 
Food analysis.
 
 The fraction of publications on this
topic (from 150 to 300 articles per year) is significant.
Analysis by gas chromatography is used for solving
two main problems in the field of food control: the
determination of the eating quality of food and the
assessment of its safety. Eating quality is determined
from the concentration of amino acids in proteins, fatty
acids and glycerides in fats, carbohydrates, organic
acids, and vitamins in different foodstuffs. Note that in
recent years many of these analyses were performed
using high-performance liquid chromatography.
Food safety is assessed by determining different
contaminating components and food additives (preser-
vatives, antioxidants, sweeteners, food colorings, etc.),
revealing the adulteration of food, and assessing its
quality and freshness (revealing early stages of degra-
dation and estimating permissible storage life of food).
The main food contaminants that are determined by
gas chromatography are pesticides, nitrosamines, myc-
 
Table 7. 
 
Number of publications on different fields of application of gas chromatography
Field of application
Year
1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1995 1996 1997 1998
Environmental pollution anal-
ysis
79 127 193 245 237 285 262 229 280 211 290 272 302 272 301 253
Food analysis – – 211 242 237 207 332 190 214 207 210 207 160 162
Drug analysis 144 168 266 323 224 252 225 215 232 215 177 209 202 209 150 142
Clinicochemical applications 63 52 70 114 89 118 60 139 132 67 63 66 27 66 52 39
Toxicological legal application 28 40 83 91 53 103 101 83 93 46 43 48 49 48 64 34
Separation of enantiomers – – – 28 42 55 42 54 81 63 97 87 97 74 56
 
208
 
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2001
 
YA.I. YASHIN, A.YA. YASHIN
 
otoxins (aflatoxins, ochratoxin A, zearalenone, etc.), poly-
nuclear aromatic compounds, biogenic amines, etc.
Note that food can be contaminated because of the
penetration of hazardous substances (in particular,
vinyl chloride, benzene, etc.) from packing materials.
Anabolic steroids, hormones, and some other types
of pharmaceuticals are determined in meat products. A
separate and very important field of the application of
gas chromatography is the analysis of the composition
of food odor. Considerable progress has been made in
this field, and it can be argued that currently there are
few foodstuffs whose odor has not been studied using
high-performance open tubular columns. A new
approach, namely, enantioselective analysis with the
use of open-tube gas chromatography was developed in
recent years [91]. From the ratio of optical isomers in
food components, it can be unambiguously decided
whether the given product is natural or synthetic. Wide
adoption of reliable gas-chromatography methods for
the analysis of food is favorable for improving its qual-
ity [92] by decreasing the concentration of residual pes-
ticides in fruit and vegetables; eliminating forbidden
additives; precluding concentrations of allowed addi-
tives higher than the permissible level; revealing adul-
terate products; decreasing the concentration of bio-
genic amines in cheese, beer, and wine; decreasing the
concentration of hormones in food; decreasing the con-
centration of 
 
trans
 
 isomers of fatty acids in margarine
and other fats; precluding the use of tryptophane pro-
duced by genetic engineering; eliminating unpermitted
processes, in particular, radiation treatment from food
processing; etc.
In natural fats,
 
 cis
 
 isomers of fatty acids are predom-
inant. Recently it was found that 
 
trans
 
 isomers of fatty
acids increase the concentration of low-density lipopro-
teins and decrease the concentration of high-density
lipoproteins in blood, which can lead to the progress of
atherosclerosis. A procedure for the gas-chromato-
graphic separation and analysis of all fatty acid isomers
was developed, and this forced the manufacturers to
decrease the concentration of 
 
trans
 
 isomers in marga-
rine several times [93].
Using gas chromatography, it was revealed that
some cheesecontains many undesirable physiologi-
cally active biogenic amines. After 
 
L
 
-tryptophane that
was produced in Japan by genetic biotechnology was used
in foodstuffs, thousands of people became ill with a new
disease and dozens of them died. Using gas chromatogra-
phy, it was revealed that these tragic events were caused
by toxic impurities in tryptophane (60 impurities were
found).
There are very many publications on the gas chro-
matography of alcoholic beverages and other alcohol-
containing products [94]. In 1997 in Russia, GOST
(State Standard) was issued on the determination of
trace impurities in vodka and edible ethanol [95] using
gas chromatography.
The chromatographic analysis of food is the subject
of books [24, 25, 28, 96] and many reviews, in particu-
lar, on the determination of volatile components in food
by the head-space method [97], on multidimensional
gas chromatography for the analysis of food odor [98,
99], on the determination fatty acids [100] and myc-
otoxins [101] in food and sugars in fruit juice [102], etc.
 
Analysis of drugs.
 
 In bibliographic indices of arti-
cles, this section is divided into the following topics:
general problems of the analysis of drugs, antirheu-
matic and antiphlogistic drugs, cardiological drugs,
drugs for treating the central nervous system, antibiot-
ics, cytostatics, and medicinal herb extracts. The largest
number of works were published on the determination
of drugs in biological fluids (blood, urine, blood plasma
and serum, etc.); rather many works deal with pharma-
cokinetics (the determination of the time of saturation
and the time of elimination of drugs from an organism).
A smaller number of publications deals with the analy-
sis of the purity of drugs, change of drugs on long-term
storage, the stability of drugs [103], and the determina-
tion of solvents in drugs. Analysis of medicinal herb
extracts attracts considerable interest. In recent years,
articles are regularly published on the analysis of drugs
of vegetable origin based on Chinese traditional medi-
cine [104], analysis of propolis [105], the determina-
tion of anticarcinogens in garlic extracts [106], etc.
 
Clinicochemical applications.
 
 The main publica-
tions deal with the use of gas chromatography both for
routine clinical analysis and for research purposes in
medicine and biology.
Gas chromatography is used for the analysis of bio-
logical fluids (blood, blood serum and plasma, urine,
saliva, gastric fluid, bile, and cerebrospinal fluid) and
other biological samples (brain, liver, tumor tissues,
myocardium, etc.).
We can mention the following most interesting
reviews: the use of gas chromatography in anesthesia
[107]; cancer studies [108]; analysis of bile acids [109],
bile alcohols [110], prostaglandins, leucotrienes [111],
 
D
 
-amino acids in blood serum of those sick with differ-
ent metabolic diseases [112], estrogens [113], and cho-
lesterol [114]; the determination of volatile compounds
in biological fluids [115]; and the determination of pen-
tane and isoprene in expired air [116] and anabolic ste-
roids in biological fluids for doping control [117]. Stud-
ies of some metabolism impairments were described
in [118].
USE OF CHROMATOGRAPHY IN FORENSIC 
AND MEDICO-FORENSIC EXPERTISE
Analytical purposes in forensic expertise are quite
different: from precise quantitative analyses to simple
comparison or revealing the identity of different sam-
ples and objects. Analytical control is important in the
inquiry of such crimes as using narcotics and alcoholic
 
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Table 8. Number of publications on different chemical compounds
Compounds
Year
1979 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1995 1996 1997 1998
Aliphatic hydrocarbons 20 26 32 43 49 55 60 64 62 65 58 67 67 52 33 29 43
Cyclic hydrocarbons 33 29 35 49 52 55 57 69 72 94 57 66 68 79 78 72 66
Halogen-containing organic compounds 27 50 45 61 81 68 88 107 96 87 70 83 99 137 119 82 82
Alcohols 17 21 33 50 61 55 78 73 64 66 56 48 45 52 46 27 34
Phenols 14 22 25 44 48 53 35 35 29 40 34 33 39 39 44 40 38
Oxo compounds and esters 21 27 26 22 33 47 49 46 43 59 50 52 44 60 39 36 45
Organic acids and ethers 41 52 58 107 139 99 115 211 299 347 223 160 162 159 133 116 110
Terpenes 3 3 5 8 15 27 23 1 35 25 34 22 27 36 19 14 22
Essential oils 4 9 19 28 33 42 61 69 69 61 36 54 73 65 52 44 45
Nitro and nitroso compounds 15 14 13 40 35 33 41 28 39 43 29 25 24 37 23 13 27
Amines and polyamines 24 38 40 68 79 50 38 43 36 36 25 21 20 16 18 15 11
Sulfur-containing compounds 18 17 25 27 31 55 60 50 48 51 44 46 55 32 18 10 27
Phosphorus-containing compounds 4 1 7 6 12 15 14 11 14 8 16 19 9 12 14 8
Organometallic compounds 29 36 23 44 56 56 72 62 55 69 47 51 58 63 47 54 56
Pesticides 46 81 91 144 148 157 124 162 174 182 139 193 213 238 194 232 165
Plastics 30 52 64 76 93 93 135 118 122 144 102 74 90 70 56 45 58
Process products 30 65 106 169 208 212 214 215 221 297 228 197 244 172 161 194 137
Permanent and noble gases 21 22 36 20 29 19 26 35 41 45 29 28 27 36 23 10 21
Volatile inorganic compounds 22 41 53 55 66 54 54 58 75 55 47 44 48 45 35 29 31
Radioactive and isotopic compounds 7 10 11 19 27 27 38 40 34 36 24 27 29 16 25 17 16
210
JOURNAL OF ANALYTICAL CHEMISTRY Vol. 56 No. 3 2001
YA.I. YASHIN, A.YA. YASHIN
beverages, unintended and intended poisoning, abuse of
drugs, murders, fires, thefts, explosions, accidents, etc.
According to recent publications, the most common
analytes in chromatographic analysis are narcotics
(morphine and its derivatives, cocaine, cannabinoids,
LSD, etc.), amphetamines, barbiturates, different drugs
and poisons, ethanol, methanol, acetone, isopropanol,
toluene, chloroform, dichloroethane, ethyl acetate, and
other solvents.
In forensic expertise, gas chromatography is also
used for the analysis of petroleum products, fuels,
lubricants, and substances that are used as combustibles
for arson and for revealing falsification and adulteration
of fuel and lubricants. Paintwork materials and coatings
including particles of automobile paint, dyes in ink for
revealing peculiarities of letters or the age of docu-
ments, timber, explosives, shot products, etc. were ana-
lyzed as well.
Hundreds of works have been published on the
chromatographic analysis of biological samples for
forensic expertise, in particular, blood, serum, urine,
saliva, sweat, expired air, human hair, etc. Only within
the last two years, hundreds of articles have been pub-
lished on the use of gas chromatography in forensic and
medico-forensic expertise. Systematic toxicological
analyses of drugs and their abuse metabolites were
developed for rapid screening [119].
Gas-chromatographic retention indices of toxico-
logically significant compounds on packed and open
tubular columns with polymethylsilicone stationary
phases were presented in [120]; mass-spectrometric
and gas-chromatographic data for drugs, poisons, pes-
ticides, pollutants, and their metabolites were presented
in [121].
The following reviews in this field are also of inter-
est: gas-chromatographic analysis of explosion prod-
ucts [112]; the determination of drugs in blood [123],
saliva and sweat [124], and hair [125] on abuse; and the
determination of amphetamines in blood and urine [126]
and benzodiazepines in biological fluids [127].
The role of gas chromatography in different fields of
forensic chemistry is adequately shown in periodical
reviews [128].
Separation of enantiomers. Enantiomeric or chiral
compounds are abundant in nature. Many synthetic
pharmaceutical compounds exhibit chirality. Com-
monly, only one stereoisomer (optical isomer) is phys-
iologically active, whereas the other is inert or even
toxic. Up to 50–100 publication yearly deal with theseparation of enantiomers by gas chromatography. It is
very important to determine the enantiomeric purity of
some drugs. As mentioned above, enantioselective
open-tube chromatography is used for the authentica-
tion of some foodstuffs and wines.
For the separation of enantiomers, the stationary
phase must be also optically active, i.e., contain asym-
metric chiral centers. For the first time, the use of an
optically active stationary phase was reported by Gil-Av
in 1966. Nowadays, optically active stationary phases of
different nature have been proposed [129–132], amide,
peptide, liquid-crystal, and cyclodextrin stationary
phases and stationary phases based on optically active
metal complexes among them.
Table 8 presents the data on the number of publica-
tions on the gas-chromatographic analysis of different
chemical compounds. The largest number of works was
published on hydrocarbons and their oxygen-contain-
ing derivatives. These compounds are also set apart in
bibliographic indices.
Table 9 presents the number of publications on bio-
genic compounds that are also specially mentioned in
bibliographic indices. The number of publications on
Table 9. Number of publications on analyses of biogenic compounds
Compounds 1979 1981 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1995 1996 1997 1998
Amino acids 21 39 51 40 45 47 50 58 43 22 38 43 35 36 25 23
Purines and pyrimidines 10 13 24 15 11 9 8 10 8 12 12 16 13 10 8 11
Alkaloids 11 2 20 17 19 17 23 27 27 36 17 28 29 22 18 18
Lipids 12 22 72 102 84 156 104 39 85 44 40 33 31 35 17 29
Monosaccharides 12 20 76 64 42 45 50 53 41 35 33 30 29 19 13 15
Polysaccharides 3 2 5 17 6 12 11 10 8 6 9 7 7 5 1 4
Vitamins 4 10 12 17 29 28 24 32 30 26 11 4 15 12 7 12
Steroids 21 23 53 38 40 59 44 69 76 77 46 74 63 40 54 40
Catecholamines 2 2 4 4 2 6 11 5 3 2 5 – 1 – 1 –
Prostaglandins 6 7 17 27 10 9 13 29 21 17 18 16 5 7 4 7
Lipoproteins 4 2 2 6 8 6 6 6 25 8 1 6 7 3 2 2
Bile acids and alcohols – 7 9 10 9 9 13 15 11 11 4 11 3 4 6 1
Flavonoids 1 1 2 3 – 2 3 3 3 6 8 9 6 9 6 6
Mycotoxins – 1 3 15 13 15 18 14 7 13 10 8 5 6 9 9
JOURNAL OF ANALYTICAL CHEMISTRY Vol. 56 No. 3 2001
CURRENT TRENDS IN GAS CHROMATOGRAPHY METHODS 211
these compounds is much smaller because currently
many of these analyses are successfully performed by
high-performance liquid chromatography.
Thus, the following most important recent advances
in gas chromatography can be emphasized:
the use of open-tube chromatography as the pre-
dominant quantitative method suitable for trace deter-
mination because of the capillary injection of large vol-
umes without splitting and the improvement of proce-
dures for preparing reproducible stable columns;
wide use of the combination of gas chromatography
with mass spectrometry because of an improvement of
reliability and a decrease in the price of chromato-
graph–mass spectrometers;
wide use of gas chromatography in vitally important
fields such as environmental control, food, drugs, med-
icine, etc.;
determination of the relationship between chro-
matographic retention and molecular structure;
miniaturization of chromatographic instruments;
development of high-speed and high-temperature
gas chromatography.
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