Head-Space Gas Chromatographic Determination of Contents of Benzene Homologues in Dispersion Paints after Extraction with n-Hexane

Seven benzene homologues,namely benzene,toluene,ethylbenzene,p-xylene,m-xylene,o-xylene and styrene,were determined by head-spacegas chromatography.As a modification of the conventional head-space method,the dispersion paint sample was pretreated by extraction with n-hexane.One mL of the gas sample was used for GC analysis.The polar column (HP-INNOWAX) was used in the separation and FID detector was used in the measurement.Qualitative analysis was done by retention time,and the external standard method was used for quantitative analysis.Linear regression equations for the 7 compounds were given with correlation coefficients in the range from 0.998 9-0.999 9.Detection limit (S/N=3) of these homologues was found to be 0.05 ng or 0.1 μg·kg-1 on the base of 0.5 g of the paint sample.In the analysis of 2 samples of dispersion paints,values of RSD′s (n=5) found for the 7 compounds were less that 5%.Test for recovery was made and results obtained were in the ranges of 90%-105% (for benzene),88%-102% (for toluene),85%-102% (for ethyl benzene),80%-98% (for xylenes) and 85%-102% (for styrene).