Determination of the herbicides frenock and dalapon in soil and river water by mass fragmentography

Abstract

A method is described for determining frenock and dalapon in environmental samples such as river waters and soils, based on the reaction of 1-benzyl-3-p-tolyltriazene with an extract of frenock or dalapon from strongly acidified sample solutions to form benzylated species, which are subsequently analysed by mass fragmentography (with soil samples, steam distillation is applied prior to the extraction).

Apiezon L grease-phosphoric acid serves as the stationary phase in GC and the molecular ions with m/z= 236 and 232 are used to monitor frenock and dalapon, respectively. The detection limits for frenock and dalapon are 0.05 and 0.5 ng, respectively, with 5 µl of sample injected. Recovery experiments using actual river water and soil samples showed recoveries of more than 92% with a coefficient of variation of less than 5%(n= 7). The method is capable of the simultaneous determination of frenock and dalapon with sufficient sensitivity and selectivity to be applicable to environmental samples.