DETERMINATION OF C-1-C-5 ALKYL NITRATES IN RAIN, SNOW, WHITE FROST, LAKE, AND TAP WATER BY A COMBINED CODISTILLATION HEADSPACE GAS-CHROMATOGRAPHY TECHNIQUE - DETERMINATION OF HENRY LAW CONSTANTS BY HEADSPACE GC

Alkyl nitrates with a chain length up to five carbon atoms have been d etermined in snow, white frost, and surface water. The samples were ta ken in the vicinity of Ulm, Germany, a region in central Europe. The d etermination of C-1-C-5-alkyl nitrates in water samples was achieved w ith a new water codistillation enrichment technique directly coupled w ith on-column head-space gas chromatography. The concentrations of the short chain alkyl nitrates in the different forms of wet deposition r ange from 89 ng L-1 for 1-propyl nitrate down to 35 ng L-1 for 1-penty l nitrate. C-1-C-5-alkyl nitrates in wet depositions were also directl y determined by static head-space gas chromatography. Gas-water partit ion 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-w ater partition constants (dimensionless) or Henry's law constants rang e from K-GW = 0.038 (H = 93 Pa m(3) mol(-1)) for 1-propyl nitrate up t o KGW = 0.122 (H = 302 Pa m(3) mol(-1)) for 2-pentyl nitrate. (C) 1998 Elsevier Science Ltd. All rights reserved.