Pyrolysis Gas Chromatographic Correlation Trials of the American Society for Testing and Materials

Abstract

Pyrolysis gas chromatography (PGC) in its present state lacks superior quantitative interlaboratory reproducibility because of small differences in chromatographic and pyroly-zer operating parameters. A cooperative testing project was organized to develop PGC into a more reproducible interlab-oratory technique. PGC test results of standard polymer samples from the United States and from the Chromato-graphy Discussion Group (London) are presented. The exper-iments were designed without bias to industry types or to particular pyrolyzer designs. To obtain better reproducibility, we adopted a calibrated PGC approach. This approach involves tuning of a gas chromatograph by retention time and peak area measurements of a known organic compound blend, followed by pyrolysis of a known polymer. GC calibra-tion is then followed by quantitative PGC of each sample three times during a 14-day period. The calibrated concept yields both superior and representative PGC data among laboratories around the world. Interesting comparisons of PGC polymer data from three testing correlations obtained with the cooperation of several American laboratories and one Japanese laboratory will be discussed. Seven different types of pyrolyzers were used In these trials: laser, quartz tube, boat, Curie point, filament, ribbon, and quartz probes. Typical pyrograms relevant to reproducibility will be illustrated.