Application of GC-MS to Qualitative and Quantitative Inspection of Polyvinyl Chloride in Polystyrene with Pyrolytic Splitting of Sample

In order to indirectly reduce the harm of polyvinyl chloride (PVC) additives to the environment and human health, the qualitative and quantitative analysis of PVC in polystyrene (PS) was made by application of GC-MS with pyrolytic splitting of sample. 1.0 mg of polystyrene sample was taken and pyrolyzed in a sample boat at 500℃ to split the PVC in the sample by dropping the HCl from the main chain, and breaking the chain to give cyclic aromatic compounds of benzene, styrene, toluene, indene, haphthalene, acenaphthene, fluorene and anthracene. These split products were separated by passing through the DB-5MS chromatographic column and measured by MS, obtaining the finger-print spectra of the split products. The spectra of split products of PVC and their retention times of the self-prepared PVC positive samples found were in consistence with those found in the spectra given by PVC standard, qualitative existence of PVC in the self-prepared PVC positive samples could be deduced. And it was found that the abundance ratios of the specific split peaks of PVC in self-prepared PVC positive samples were in consistence with those of the PVC standard, showing that there was no interfering substance present in the analysis of PVC, hence the split product of benzene could be determined for the quantification of the PVC in the sample. Self-prepared samples of PVC were used to prepare the working curve in the same way as the sample analysis, and linear relationship was obtained between mass of PVC in the range of 0.5 to 50 μg and values of peak areas of benzene (m/z 78). Detection limit (3S/N) found was 106 mg·kg^-1. Six parallel determinations of a known sample containing 20 μg of PVC for working curve were carried out and value of RSDs (n=6) found was 3.6%. Recovery was made by analyzing the 9 self-prepared PVC positive samples with known PVC contents, giving values of recovery over 84.0%.