Gas Chromatography in Coating Analysis

By Francis V. Acholla ,

Gas chromatography (GC) is an established standard analytical tool for the analysis of coatings and related materials. Many volatiles and semivolatile compounds such as residual monomers, solvents, and plasticiz­ers, and low molecular weight additives such as mildewcides and antifoaming agents can easily be analyzed by GC.

Headspace-gas chromatography/mass spectrometry (HSGC/ MS) is used for routine analysis of odor prob­lems and for analyzing volatiles in situations where solvent extraction and/or sample dilu­tion are not appropriate. Less volatile com­pounds, such as polymers, resins, and waxes can be analyzed by pyrolysis/CC-MS and/or derivative pyrolysis-CC/MS, such as methy­lation with tetramethylammonium hydrox­ide (TMAH).

Gas chromatography (GC) con­tinues to play a vital role in the analysis of coatings and related ma­terials. This article focuses primarily on those areas where new insights have emerged in the literature and in our laboratories in the last sev­eral years. The reader is encouraged to review references 1-4. Gas chro­matography involves a sample being vaporized and injected onto the head of the chromatographic col­umn.

A schematic diagram of the basic components in a GC system is shown in Figure 1. The sample is transported through the column by the flow of inert, gaseous mobile phase (Ar, He, CO2 and N2). The choice of a carrier gas normally de­pends on the type of detector used. The column itself contains a liquid stationary phase, which is adsorbed onto the surface of an inert solid.