Determination of volatile carboxylic acids in animal wastes by (GC)² of their benzyl esters

The C 1 ‐C 6 fatty acids present in various types of heterogeneous animal wastes were isolated by steam distillation and determined as benzyl esters by high resolution gas chromatography. Glass capillary columns, deactivated with barium carbonate and coated with UCON HB 5100, allowed the analysis of benzyl formate, acetate, propionate, isobutyrate, butyrate, isovalerate, valerate, and caproate in less than 20 minutes. Recovery tests, performed on more than 50 different samples, indicated a benzylation yield and an overall efficiency higher than 99%, with a standard deviation of 2.6% (C 5 ) to 6.0% (C 1 ). The absolute detection limit ranged from 0.3 picomole (caproic acid) to 1.0 picomole (formic acid).