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 365nm 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 0.02–0.5mgL −1 (r=0.9988). Limit of detection was 2.0μgL −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, 1.5mgkg −1 ), the recoveries ranged from 67.5 to 82.1%, with relative standard deviations between 4.5 and 7.3%.0.01molL −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.