Chloroacetic acids in rainwater

From 1993 to 1995, chloroacetic acids have been determined in rainwater collected near the center of Zurich and in a rural area of Switzerland (Alpthal). The chloroacetic acids have been enriched either by evaporation or by anion exchanger, derivatized to their respective propyl esters, and determined by gas chromatography(GC) with electron capture detection (ECD), by coupled-column GC-ECD (GC-GC-ECD), or by GC/mass spectrometry(MS). Monochloroacetic acid is most abundant, followed by dichloro- and trichloroacetic acid. Concentrations range from 0.01 up to 9 mu g/L; the dependence on meteorological conditions and sampling site is discussed.