A new method for the determination of trichloroacetic acid in spruce foliage and other environmental media

Trichloroacetic acid (TCAA) is a phytotoxic chemical, present throughout th e environment. The majority of methods for analysis of TCAA require chemica l derivatisation and multiple extraction steps prior to analysis by gas-chr omatography. Here, a new analytical method for TCAA determination in enviro nmental matrices is reported. The method is based on a modified Nielsen-Kry ger steam distillation that combines into one 1 h reflux the thermal decarb oxylation of TCAA to CHCl3 and the partitioning and concentration of the CH Cl3 into 5 ml of hexane, which is analysed by GC. Sample preparation is min imal and no matrix standard additions are required. The background CHCl3 in the sample is removed prior to extraction by degassing the solution for 1 h with nitrogen. Optimisation of the method gave recoveries from three sepa rate solutions of 0.31 ppb aqueous TCAA standards of 93 +/- 15% (n = 9), 11 0 +/- 9% (n = 9) and 105 +/- 11% (n = 6). The extraction method has been co mpared with a decarboxylation and headspace GC method for determination of TCAA in Sitka spruce needles. No significant difference in TCAA concentrati on or replicate precision between the two methods was observed.