Collection and ion chromatographic determination of nitrous acid in air
An active sampling method based on a solid-phase collection medium was used to determine nitrous acid concentrations in indoor air. A carbonate-bicarbonate coated filter was found to be inefficient for collection of nitrous acid. An amino type, weak anion exchange cartridge was used to collect nitrous acid, which was then eluted from the cartridge using the carbonate-bicarbonate mobile phase. Nitrous acid concentration was determined by anion exchange chromatography (AEC) using conductivity detection on a Dionex Ion Pac AS9 column. The method was applied to quantify the nitrous acid in a model environmental tobacco smoke (ETS) situation and is reproducible with a relative standard deviation of 3.9%. Percent recovery was about 97%. Analyses of samples collected from various sources showed that nitrous acid concentrations vary in cigarette smoke, internal combustion engines and outdoor air. With a relatively short sampling time of 6h, this procedure was capable of detecting nitrous acid above 2 microng m-3.