Determination of volatile organic compounds in ambient air. Comparison of methods.

Two analytical methods for the determination of benzene vapour in ambient air are compared in this paper. The methods differ from each other in the sampling technique, type of sorbent, method of extraction and method of detection. The investigation of the methods using various techniques for sample analysing showed a significant influence of the way in which the analysis is carried out, on the final result of the analysis. Calculation of the standard deviations, relative standard deviations and confidence intervals allowed for assessment of the precision and repeatability of the methods. Of the two examined methods, that using an automated system of contaminant sampling and thermodesorption was more precise. This method has been applied to measurements of concentrations of benzene, toluene and xylenes in ambient air.