Determination of Vinyl Chloride Monomer in Poly(vinyl chloride)(PVC)Pipes by Dissolution Precipitation-Headspace-Capillary Gas Chromatography

A new method was established for the determination of vinyl chloride monomer in poly(vinyl chloride)(PVC)pipes by dissolution precipitation-headspace-capillary gas chromatography with flame ionization detector(FID).The principle of this method was based on that a proper percent of water added to N,N-dimethylacetamide(DMA)solution could decrease the solubility of vinyl chloride in DMA solution and thus increase the concentration of vinyl chloride in gas phase.Smashed pipes were dissolved by DMA and water was added to precipate the polymers.4 mL DMA solution with 37.5%(by volume)water was used for the dissolution and precipitation of the polymer.The samples were injected into the gas chromatograph with headspace sampler after equilibrated at 75 ℃ for 35 min.The vinyl chloride was separated by HP-Wax capillary column and quantified by the external standard method.The calibration curve of vinyl chloride was linear in the range of 0.025-2.50 mg/L(r=0.999 3).The limit of detection(S/N=3)was 4.75 μg/L,which is 9 times higher than that of the conventional headspace gas chromatography.The spiked recoveries of vinyl chloride were in the range of 90%-96% with relative standard deviations(RSDs,n=6)less than 6.0%.The new method was simple,convenient,sensitive and accurate,and was suitable for the determination of vinyl chloride monomer in PVC pipes.