ANALYSIS OF THE HERBICIDE CLOPYRALID IN CULTIVATED SOILS

Clopyralid is a broad-spectrum herbicide for thistle control in vegeta ble cultivation. Its application rate amounts to 0.2 kg/ha. However, c ontradictory results in soil leaching experiments require a reliable r outine procedure for trace analysis of clopyralid in soil. Previously reported methods for clopyralid analysis in several matrices either pr oved to be insufficient for analysis in soil and leaching water or req uire the use of critical chemicals and are too complicated for routine analysis. The problem of poor extraction recovery of clopyralid from soil rich in humic acids was solved by phase transfer extraction of so il samples. Analysis of the extract was performed by GC-MS directly af ter the extractive phase transfer catalytic reaction. Tetrabutylammoni umhydroxide served as a phase transfer catalyst. For improving analyti cal reliability, 2.5-dichlorobenzoic acid was used as an internal stan dard. Detection limit (1 mu g/kg=1 ppb) and quantification limit (10 m u g/kg) of clopyralid in soil were found to be appropriate for determi ning the behaviour in herbicide treated soils, The leaching and disapp earance of clopyralid in two differently tilled soils were determined in field trials.