Table Of ContentGAS PHASE CHROMATOGRAPHY
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GAS PHASE
CHROMATOGRAPHY
Volume I
GAS CHROMATOGRAPHY
RUDOLF KAISER
Badische Anilin- und Sodqfabrik AG Ludwigshafen
Translated by
P. H. Scott
LONDON
BUTTER WOR THS
1963
ISBN 978-1-4684-8293-5 ISBN 978-1-4684-8291-1 (eBook)
DOl 10_1007/978-1-4684-8291-1
Originally published under the title
Chromatographie in der Gasphase
Band I Kapillar-chromatographie
by Bibliographisches Institut AG Mannheim
© 1960 Bibliographisches Institut AG Mannheim
Softcover reprint of the hardcover 1s t edition 1960
English Translation
©
Butt6IWorth &: Co. (Publishers) Ltd.
1968
FOREWORD
THE present volume, which is the first of a three-volume work on gas
phase chromatography, deals with the problems of gas chromatography
in packed columns.
Gas chromatography, like any other analytical method, is mainly a
matter of practical skill, and therefore emphasis has been given to the
apparatus at the expense of a more detailed presentation of the theory.
The aim of this book is to make lecturers and students, chemists, works
engineers and laboratory workers familiar with this highly effective branch
of analytical physical chemistry. I hope too that the experienced worker
may find references which will be of value to him in his work and which
will spare him part of the now almost impossible task of keeping up to
date with the literature.
The nomenclature used here is the result of a number of discussions
with Professor E. Cremer and Dr. E. Bayer, and I should like to take this
opportunity of expressing my grateful thanks to them.
The present book is based partly on my book Gas Chromatography which
appeared at the end of 1959. Numerous discussions with Professor E.
Leibnitz and his colleagues H. P. Angele, M. Hofmann, H. Holzhauser,
M. Kuhl and H. G. Struppe and the experimental work carried out with
them have all influenced this revision.
I should also like to thank Dr. H. Kienitz and his colleagues Dr. K.
Dorfner, Dr. H. D. Ermshaus and Dr. H. Runge for valuable suggestions.
Beckm.ilnn Instruments, GmbH, Munich, Perkin-Elmer & Co., Boden
seewerk, Uberlingen, Griffin & George Ltd., Alperton, \Vembley, W. G.
Pye & Co. Ltd., Cambridge, and the organizers of the 3rd Gas Chromato
graphy Symposium at Edinburgh in 1960 have all been most generous in
supplying me with data and illustrative material.
I should also like to thank the Verlag Bibliographisches Institut,
Mannheim, for their splendid co-operation.
RUDOLF KAISER
v
CONTENTS
FOREWORD v
INTRODUCTION
Survey of the four fundamental chromatographic methods
Limits of application, definitions and methods of gas chromato
graphy-Nomenclature-History of gas chromatography.
1. THEORY OF GAS CHROMATOGRAPHY.. 10
Definition and derivation of the characteristic values for gas
chromatography-Retention volume and partition coefficient
Retention values and the liquid phase in isothermal gas
chromatography-Height equivalent to a theoretical plate
Separation formula for gas chromatographic methods-Selec
tivity, column performance and resolution-Retention values
and temperature of separation; retention temperature
Number of theoretical plates and peak form-Gas chroma
thermography by the circulation technique.
2. APPARATUS 34
2.1. The column.. 37
The column packing-Evaluation of packed columns
Calculation of the number of theoretical plates, column per
formance and separation factor-Resolution-Calculation of
the number of theoretical plates or column length necessary for
a given separation-Load capacity-Performance index
Time of analysis and resolution-Column material-Column
diameter-The solid support-Removal of residual adsorption
activity-Particle diameter-The liquid phase-Quantity of
liquid phase-Impregnation of the support-Testing the column
packing-Peak form-Control of the quantity of liquid phase
-Temperature load capacity-Filling the column-Testing
the column-Ageing of the column packing-Summary of the
factors governing the preparation and operation of efficient
columns.
2.2. The carrier gas 65
Gas purification-Control and measurement of the carrier gas
flow rate-Disturbances of constant flow rate-Production of a
constant gas flow rate-Gas tightness-Flow rate meters.
2.3. The sample injector 79
Sample injectors for gases-Sample injectors for liquids.
2.4. Detectors 99
Desirable and necessary properties of detectors-Principles
of measurement-The thermal conductivity cell-The flame
ionization detector-Testing of detectors-Comparison of
sensitivity.
vii
Contents
2.5. Recorders 125
2.6. Temperature 127
The optimum operating temperature-Constant tempera
ture-Temperature control-Heat insulation-Variable tem
peratures.
2.7. Industrial gas chromatographs and other special apparatus 143
High temperature instruments-Multi-column instruments
Apparatus for preparative work-Sample collection systems
Fully automatic instruments-Trace analysis instruments-Low
pressure instruments.
3. THE ANALYTICAL RESULT 165
3.1. The qualitative analytical result 167
Preparation of the sample-Choice of the most suitable column
and operating conditions-Qualitative evaluation-Qualitative
testing of columns.
3.2. The quantitative result 179
Requirements for the quantitative evaluation of gas chromato
graphic results-Measurement of peak area-Evaluation from
peak area measurements-Direct surface area method-Evalu
ation by peak area measurements using specific calibration
factors-Evaluation of the analysis by a calibration method
External calibration of the peak heights-External calibration
of the peak areas-Internal calibration with addition of ex
traneous substance-Internal calibration with component
already present-Evaluation by the height and area methods for
constant sample quantity-Evaluation methods using integral
detectors.
3.3. Application of gas chromatography to the determination of
thermodynamic values 191
INDEX 195
viii
INTRODUCTION
DURING recent years gas chromatography has developed into the most effec
tive of the chromatographic analytical methods. With its aid qualitative and
quantitative separations and determinations can be carried out on mixtures
of any substances which vaporize without decomposition under the condi
tions of gas chromatography or which can be decomposed in a reproducible
manner. This includes all organic and inorganic substances with definite
boiling points, all substances capable of being converted into stable end
products, and all those substances which, although originally not covered by
these terms, can be converted into vaporizable or decomposable deriva
tives.
Gas chromatographic methods can be used for automatic operation.
This is why their use in works laboratories, pilot plants, and full-scale
chemical plants is widespread and still increasing. Modern gas chromato
graphic methods require only a thousandth to a millionth of a gram of
substance for an analysis, and can be completed within minutes or even in
seconds. The new method provides a valuable extension of the range of
analytical techniques, not only for the chemist but also for the biologist and
the medical man.
The present volume presents the theory of gas chromatography with
packed columns, the so-called classical method, in a form which is very
simple but is useful for the practician.
A good understanding of the apparatus used in gas chromatography is
essential, since in many cases it is necessary to build one's own or to modify
existing equipment; in order to assist this and also to help select the most
suitable commercial instrument for the job in hand, Volume I gives a very
thorough treatment of apparatus problems.
Finally the qualitative and quantitative application of gas chromato
graphy to a few selected practical examples is described in a systematic and
generalized manner.
Volume II, which will follow later, will deal with the theory, apparatus
and application of capillary gas chromatography. The latter method was
only recently developed from classical gas chromatography as a new and in
many cases very efficient variant.
Finally the third volume will contain in tabular form all the important
data which are necessary or useful for the widest possible application of
classical and capillary gas chromatography for qualitative and quantitative
analysis, and also for industrial gas chromatography.
Survey of the Four Fundantental Chrontatographic Methods
The term 'chromatography' is at present understood to include all those
processes in which separation is brought about by adsorption or solution
partition of a mixture between two non-miscible phases.
Introduction
The two phases flow in intimate contact countercurrent to one another,
or one phase is stationary and the other phase flows intensively through it.
For the mobile phase only two states of matter can be considered: liquid
or gas. Only liquid or solid substances may be used for the stationary phase.
Mobile phase Stationary phase
G gas L liquid (liquidus)
L liquid S solid (solidus)
By combinations of these the four possible chromatographic methods
(abbrevated to C) are obtained:
GLC}
Gas chromatography
GSC
LLC } Column, paper, and partition chromatography, and
SLC ion exchange.
The following table shows when and by whom the individual methods
were first discovered.
SLC Tswett (1906)
GSC Schuftan (1931), or Ramsey (1905)
LLC Martin, Synge (1941)
GLC James, Martin (1952) or Damkoh1er, Theile (1943)
There are four techniques by which the separation can be carried out:
1. By elution (elution analysis)
2. By displacement with the mixture itself (frontal analysis)
3. By displacement with an auxiliary substance (displacement analysis)
4. By circulation of a temperature field (circulating chromathermo
graphy)
Almost all the chromatographic methods can be carried out by the four
techniques:
GLC: Elution, frontal and circulating chromathermography
GSC: Elution, frontal, displacement and circulating chromathermo-
graphy
LLC: Elution, frontal and displacement analysis
SLC: Elution, frontal and displacement analysis
Modern techniques, however, favour the elution process, because it is
much easier to control than frontal and displacement analysis.
Lindts of Application, Definitions and Methods of Gas
ChroInatography
The general term 'gas chromatography' includes all those chromato
graphic processes in which the essential material transport occurs in the
gaseous or vapour phase.
The applicability of gas chromatography is limited to those substances
which may be vaporized under normal conditions or which may be
2
Limits of Application, Definitions and Methods
decomposed in a reproducible manner to give stable gaseous products. It
may also be applied to substances which, although not capable of being
vaporized or converted into gaseous products in their original form, can be
converted by given chemical reactions into substances with the required
properties.
The range of application thus includes all gases, all liquid and solid
substances capable of being distilled, all substances which may be decom
posed in a reproducible manner such as polycondensates, polymerizates,
salts of non-volatile acids, organic complexes of many metals, halides of the
transition elements, etc.
We can therefore make the following definition:
Gas chromatography is a rapid process for the separation and analysis of
all substances which can be vaporized or decomposed, or which can be
chemically converted into such substances. By this means qualitative and
quantitative analytical results can be obtained.
There are several gas chromatographic processes; they may be distin
guished on the one hand according to the principle of separation, on the
other according to the method of operation.
There are two different principles of separation:
1. Gas-solid chromatography (GSC) or adsorption gas chromatography. This principle
depends on the variation in the extent to which the constituents of a
mixture are adsorbed on an adsorbent such as activated carbon, silica gel,
alumina, clay, molecular sieves, etc.
2. Gas-liquid chromatography (GLC) or partition gas chromatography. This principle
depends on the varying solubilities of the vapours of the constituents in
the liquid phase, which may be a substance such as tricresyl phosphate,
paraffin oil, glycerine, etc.
Each of these principles can be carried out at either constant or fluctuat
ing temperature. The operating temperature may rise steadily or discon
tinuously, but a rising or falling temperature field can also recur in a cyclic
fashion. We therefore speak of isothermal gas chromatography or gas chromather
mography.
Further, we may distinguish four different methods of operation:
(a) The elution or development technique. In this method the mixture is
'transported' through a tube, or separating column, packed with adsorbent
or impregnated with liquid phase, by means of a so-called 'carrier gas',
which flows continuously and steadily. As a result of this continuous trans
port of material through the column, the different rates of travel of the
individual constituents effect the desired separation.
The essential thing about this method is that the substance need only be
introduced into the column inlet on one occasion, at the start of the analysis,
and that only a small amount of substance is required.
, (b) The displacement technique. The continuously flowing carrier gas is satur
ated with the vapour of a substance which is adsorbed by the column packing
3
