A new method for the determination of methyl- and butyltin compounds in aqueous samples is presented. The organotin species are derivatized in situ with sodium tetraethylborate (NaBEt4) in an 800-ml sample, purged on-line with helium and cryofocused at −40°C in the Tenax-filled glass insert of a modified split/splitless injector. The injector is equipped with a liquid nitrogen cooling and a heating wire which serves for programmed-temperature vaporization. After thermal desorption the peralkylated tin species are refocussed on the capillary GC column at 10°C followed by GC separation and mass spectrometric detection in the full scan mode. All steps are computer-controlled so that once the derivatizing reagent is added, the analysis is performed automatically. The concentration of NaBEt4, the reaction time, the purge flow-rate and the purge time were optimized. The preconcentration of sample volumes of 800 ml led to detection limits in the range of 1–2 ng Sn/l. Due to the compound specific information of the full scan mass spectra, the presented method is a powerful tool for the speciation of alkyltin compounds in aqueous samples.

Distillation as a way of sample digestion has been combined with on-line RP C18 preconcentration and HPLC-UV-PCO-CVAAS (high performance liquid chromatography — ultra violet — post column oxidation — cold vapour atomic absorption spectrometry) for the determination of methylmercury at back-ground levels in sediments, soils and fish tissue. To prove the accuracy of this method, it was applied to sediment and fish tissue reference materials. The results correspond with the reference values within their error ranges. Excellent recoveries (92–95%) were obtained for the sediment samples by means of the standard addition method. The standard deviations of the sediment samples were within an acceptable range (7.2–12.5%), those of the fish samples were substantially lower (3.4–5.0%). The detection limit is 0.04 ng/g for 1 g sample weight.

We measured ionic compounds in rain and fog at two remote sites in the South Island of New Zealand and at two sites in the Fichtelgebirge, F. R. of Germany. In the Fichtelgebirge high concentrations of H3O+, NO 3 − , SO 4 2− and NH 4 + indicate an anthropogenic impact, whereas in New Zealand concentrations were generally very low except for seasalt derived ions such as Na+, Cl− and Mg2+ at one site near the coast which receives precipitation from maritime sources. Remarkable differences occur in the acidity of hydrometeors in New Zealand and the Fichtelgebirge. The low pH values of the Fichtelgebirge (pH ≈ 4.2) are due to an excess of strong mineral acids, whereas the acidity of rain and fog in New Zealand is controlled by dissolved CO2 (pH ≈ 5.6). In the Fichtelgebirge, acidity in fog is much higher than in rain, whereas no difference could be observed in New Zealand due to marine influences and the lack of strong mineral acids. Rain of different trajectories of air flow in New Zealand is accompanied by a wide range of ionic concentrations.

On observe une plus forte concentration en polluants dans les eaux de brouillard que dans les eaux de pluie