Factors affecting signal intensity in headspace mass spectrometry for the determination of hydrocarbon pollution in beach sands.

One of the main limitations to the use of direct coupling of headspace mass spectrometry (HS-MS) for the quantitative determination of analytes in a sample is related to factors affecting the signal intensity. The importance of strategies aimed at compensating this problem is considerable in the case of classification, and is indeed critical as regards the problems involved in quantification. This paper reports the effects of the different factors affecting HS-MS signal intensity in the quantification of the pollution of beach sands by hydrocarbons--the matrix effect, signal instability over time and nature of the different pollutants present in the polluted sands--and proposes possible solutions. Signal instability was solved by using a multiplicative calibration transfer algorithm. A three-factor Box-Behnken experimental design was used to study the matrix effect, mainly as regards the moisture of the samples, and the results are discussed.