Simple multi-residue analysis of persistent organic pollutants and molecular tracers in atmospheric samples 

We present a simple, selective and sensitive analytical method to quantitatively determine a wide range of halogenated persistent organic pollutants and molecular tracers in atmospheric samples. Identification and quantification was carried out by high-resolution gas chromatography, hyphenated with low-resolution mass spectrometry operating in electron impact (EI) and electron capture negative ionization (ECNI) mode. Optimization on a number of instrumental parameters was conducted to obtain ultra-trace detection limits, in the range of few fg/m3 for organohalogen compounds. Repeatability and reproducibility of the method was thoroughly evaluated. The analysis was validated with standard reference materials and successfully applied to actual atmospheric samples. The proposed multi-residue method provides a precise, affordable and practical procedure of sample analysis for environmental research laboratories with conventional instrumentation on a routine basis. & BULL; A simple combination of alumina, florisil and silica gel adsorbents was applied to sufficiently isolate polychlorinated biphenyls, organochlorine pesticides, polycyclic aromatic hydrocarbons, long chain n-alkanes, hopanes and steranes. & BULL; Full elution was achieved in two successive fractions, using small volumes of n-hexane and n-hexane/dichloromethane to recover all target substances. & BULL; To maximize analytical response, optimization was applied for three operating parameters in ECNI mode: i) ion source temperature; ii) emission current; and iii) electron energy.