Characterisation and optimisation of a sample preparation method for the detection and quantification of atmospherically relevant carbonyl compounds in aqueous medium

摘要

Carbonyl compounds are ubiquitous in the atmosphere and either emittedprimarily from anthropogenic and biogenic sources or they are producedsecondarily from the oxidation of volatile organic compounds. Despitea number of studies about the quantification of carbonyl compounds acomprehensive description of optimised methods is scarce for thequantification of atmospherically relevant carbonyl compounds. The methodoptimisation was conducted for seven atmospherically relevant carbonylcompounds including acrolein, benzaldehyde, glyoxal, methyl glyoxal,methacrolein, methyl vinyl ketone and 2,3-butanedione.-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine hydrochloride (PFBHA) was usedas derivatisation reagent and the formed oximes were detected by gaschromatography/mass spectrometry (GC/MS). With the present methodquantification can be carried out for each carbonyl compound originatingfrom fog, cloud and rain or sampled from the gas- and particle phase inwater. Detection limits between 0.01 and 0.17 μmol L werefound, depending on carbonyl compounds. Furthermore, best results were foundfor the derivatisation with a PFBHA concentration of 0.43 mg mL for24 h followed by a subsequent extraction with dichloromethane for 30 min atpH = 1. The optimised method was evaluated in the present study by the OHradical initiated oxidation of 3-methylbutanone in the aqueous phase. Methylglyoxal and 2,3-butanedione were found to be oxidation products in thesamples with a yield of 2% for methyl glyoxal and 14% for2,3-butanedione after a reaction time of 5 h.