Determination of trace trichlorfon by high performance liquid chromatography with UV detection based on its catalytic effect on sodium perborate oxidizing benzidine.

Trichlorfon has the capacity to catalyze the oxidation of benzidine (4,4'-diamino-biphenyl) to 4-amino-4'-nitro biphenyl in the presence of sodium perborate. The product of the catalyzed reaction was validated by LC-MS method. Reversed-phase high performance liquid chromatography with 365 nm UV detection was used for separation and quantification of 4-amino-4'-nitro biphenyl. It can be proven there is a linear relationship between the peak areas of 4-amino-4'-nitro biphenyl and trichlorfon in the concentration range of 0.02-0.5 mg L(-1) (r=0.9988). Limit of detection was 2.0 microg L(-1). A method for the indirect determination of trichlorfon using HPLC was developed based on catalytic effect of trichlorfon. Method validation was performed on samples spiked at three levels (0.5, 1.0, 1.5 mg kg(-1)), the recoveries ranged from 67.5 to 82.1%, with relative standard deviations between 4.5 and 7.3%. 0.01 mol L(-1) sodium dodecyl sulphate (SDS) solution was used to extract trichlorfon from samples and solid-phase extraction was used to isolate and concentrate trichlorfon in SDS solution. The recoveries of trichlorfon obtained with percolating the extraction through a SPE system were essentially in agreement with those obtained by liquid-liquid extraction. This new isolation technique decreases the use of toxic solvents and satisfies the requirements of Green Analytical Chemistry.