Determination of C 1-C 5 alkyl nitrates in rain, snow, white frost, lake, and tap water by a combined codistillation head-space gas chromatography technique. Determination of henry's law constants by head-space GC

Abstract

Alkyl nitrates with a chain length up to five carbon atoms have been determined in snow, white frost, and surface water. The samples were taken in the vicinity of Ulm, Germany, a region in central Europe. The determination of C 1C 5-alkyl nitrates in water samples was achieved with a new water codistillation enrichment technique directly coupled with on-column head-space gas chromatography. The concentrations of the short chain alkyl nitrates in the different forms of wet deposition range from 89 ng L −1 for 1-propyl nitrate down to 35 ng L −1 for 1-pentyl nitrate. C 1C 5-alkyl nitrates in wet depositions were also directly determined by static head-space gas chromatography. Gas-water partition coefficients K GW (Henry's law constant H) were determined by head-space gas chromatography and secondly by calculating the Henry's law constant by the ratio of vapor pressure to water solubility. The gas-water partition constants (dimensionless) or Henry's law constants range from K GW = 0.038 (H = 93 Pa m 3 mol −1) for 1-propyl nitrate up to KGw = 0.122 (H = 302 Pa m 3 mol −1) for 2-pentyl nitrate.