LIQUID-CHROMATOGRAPHIC DETERMINATION OF BENTAZON IN TECHNICAL AND FORMULATED PRODUCTS - COLLABORATIVE STUDY

An isocratic reversed-phase liquid chromatographic (LC) procedure for measuring bentazon in commercial herbicide products and aqueous formulations was collaboratively studied by 16 laboratories. Samples are dissolved in LC eluent [0.075M sodium acetate-methanol (60 + 40)] and analyzed by LC on a 30 cm x 3.9 mm octadecylsilyl column with detection by UV absorbance at 340 nm. The quantity of active ingredient is determined by comparing the mean response factor (RF) of the sample to the mean RF of standards injected just before and after each pair of sample injections. The average relative standard deviation (RSD(R)) for 3 formulations studied was 1.54%; the RSD(R) for a technical sample was 0.77%. The method has been adopted first action by AOAC INTERNATIONAL.