A chromatographic method to analyze products from photo-oxidation of anthropogenic and biogenic mixtures of volatile organic compounds in smog chambers

Analytical methodologies for oxidized organic compounds in the atmosphere

“…The analysis of aerosol samples is challenging due to their complexity, which is why gas chromatography (GC) methods have often been applied to the analysis of aerosol samples. 82 One crucial requirement is the volatility of the analytes, which does not apply to highly oxidized compounds with reduced vapor pressure. 83 Thereby, the compounds cannot be analyzed in their native form, but need to be derivatized to increase volatility.…”

“…66 Reactions are slow and a minimum of 20 hours has been required for the reactions to proceed at room temperature. 66,68,82 The reactions are even slower with ketones, and to achieve quantitative reaction, heating the reaction mixture at 60 °C (or higher) for two hours using MHA as a reagent has been suggested. 95 Quantitative reaction has been achieved by heating at 70 °C for one hour, 101 but recoveries have been about 70% or less for carbonyl compounds in field samples.…”

“…9,34,82 The reaction has been accelerated by heating at 70–80 °C for 30–60 minutes. 27,36,82,86 Silylation is possible to perform in the gas phase, which could occur during the injection into a hot GC injector. 103…”

“…For example, anhydrides are converted into acids by water extraction, which will increase their concentration. 82 Bateman et al 96 demonstrated artifact formation as carbonyl species and organic acids were converted into hemiacetals, acetals, and methyl esters when MeOH was employed in the extraction.…”

“…Possible reagents are O-methylhydroxylamine (MHA), 34,87,89,95,101 O-benzylhydroxylamine (BHA), 66,68,90 O-tert-butylhydroxylamine, 104,105 and O-(2,3,4,5,6-pen-tauorobenzyl)hydroxylamine (PFBHA). 82,106 Oxime derivatives have been mainly applied for GC analyses, but they can also be employed in LC. 68 Oxime derivatization can be performed in an organic solvent (MeOH, ACN, DCM, and their mixtures) or in an aqueous matrix.…”