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For the separation and isolation of simple chemical compounds, the molecular weights of which in general do not exceed 600, gas chromatography offers one of the most flexible and adaptable analytical techniques available in the modern laboratory. It is only just over 25 years ago that the first successful applications of this technique were reported by James and Martin, yet modern commercial gas chromatographs exhibit a high degree of refined engineering applied to the separation procedures themselves which, when combined with microprocessor control and other recent developments in the field of electronic data handling, offer to the analyst considerable scope for the examination of even the most intractable samples. In the paint industry the facilities offered by gas chromatography are being fully exploited in the analysis of raw materials, notably solvents, monomers, oils and fats; in the analysis of finished paints and in the control of the working environment as demanded by present‐day health and safety regulations. This article presents a review of the analytical procedures that are possible using modern gas chromatography techniques.

In view of the changes which have taken place in this field in recent years, it is perhaps a suitable time to review the fundamentals of the subject, in order that the significance of recent developments might not be lost for the surface coatings analyst.

The introduction of gas chromatography by James and Martin in 1952 has been one of the factors contributing to the development of precise detection and monitoring devices across the whole field of chromatography. At the same time the rapid development of solute detection devices has reflected the advances and refinement of chromatographic techniques over the last twenty years.

In order to examine satisfactorily certain substances by gas chromatography they must first of all be converted into suitable derivatives with volatilities much greater than those of the parent compounds. In this class of materials are the fatty acids associated with the triglyceride oils used in alkyd resin manufacture, along with the polycarboxylic acids and polygols which are also used for this purpose. It can generally be expected that compounds containing polar functional groups that are capable of hydrogen‐bond formation will, when these are converted into suitable derivatives, be much more volatile than the parent compounds on account of the loss of these secondary bonds. It is this increased volatility which enables the substances to be successfully analysed by gas chromatography at temperatures which do not cause their thermal degradation.

Until comparatively recently, in the practice of gel permeation chromatography it has been customary to use porous gel beads that have an average diameter in the range between 75 and 100 microns, and which are packed into columns up to 4ft long and having an inside diameter of approximately 0.3in, in order to achieve a separation. A working pressure in the region of 40 psi is normal for each of these columns when eluted with solvents such as toluene or tetrahydrofuran (THF) at ambient temperature. Therefore, a pump that is capable of producing a steady pulseless flow at around 300 psi is sufficient to meet the working requirements of a combination of up to seven such GPC columns. At the customary flow rate of 1cm3 min‐1 a chromatograph equipped as described would produce a GPC scan of whole polymer in about 3 hours.

Until recently liquid chromatography has been a somewhat neglected branch of science. However, the availability of precision equipment, and even complete instruments, has made possible liquid chromatography separations of a more advanced nature. For example, suitable detectors have been developed, and pumps are available which deliver accurate volumes of solvent under pressure.

Vinyl acetate was polymerised at −24°C, under an atmosphere of nitrogen and using an Hanovia 100‐W mercury arc lamp, by Atkinson et al. (2) who then subjected the product to preparative GPC using a Waters Associates AnaPrep chromatography unit fitted with columns (1.2m × 2.5cm dia. or 1.2m × 6.25cm dia.) that were packed with Styragel chosen to suit the MSD of the samples as previously determined in a separate analytical GPC run. Fractions from several runs, that were obtained by elution with toluene at a flow rate of 15mL min−1, were combined together prior to recovery of the polymer samples by freeze drying the solutions now in benzene. The Mn of each fraction so obtained was determined in toluene at 40°C using a Hewlett‐Packard model 502 osmometer fitted with Arro 450 special membranes.

The analysis of acetate acrylic and acrylic copolymers systems is described. Much useful information is rapidly obtained by infra‐red spectrophotometry and pyrolysis gas chromatography, however quantitative analyses generally require the polymer material to be cleaved by chemical means with subsequent identification of the fragments by gas chromatography.