IN-SITU METHYLATION OF STRONGLY POLAR ORGANIC-ACIDS IN NATURAL-WATERSSUPPORTED BY ION-PAIRING AGENTS FOR HEADSPACE GC-MSD ANALYSIS

Strongly polar organic substances like halogenated acetic acids have b een analyzed in surface water and groundwater in the catchment area of the upper Elbe river in Saxony since 1992. Coming directly from anthr opogenic sources like industry, agriculture and indirectly by rainfall , their concentrations can increase up to 100 mu g/L in the aquatic en vironment of this catchment area. A new static headspace GC-MSD method without a manual pre-concentration step is presented to analyze the c hlorinated acetic acids relevant to the Elbe rivers as their volatile methyl esters. Using an ion-pairing agent as modifier for the in-situ methylation of the analytes by dimethylsulfate, a minimal detection li mit of 1 mu g/L can be achieved. Problems like the thermal degradation of chlorinated acetic acids to halogenated hydrocarbons and changing reaction yields during the headspace methylation, could be effectively reduced. The method has been successfully applied to monitoring bank; infiltrate, surface water, groundwater and water works pumped raw wat er according to health provision principles.