Abstract: Sample was adjusted to pH 7-8 and then 136 µL of the solution was injected and transferred by a carrier stream of 1% HCl at 1.4 ml/min to react with streams of 1% aniline and 4% K2S2O8 at 1 and 0.77 ml/min, respectively, in a reactor (96 cm x 0.77 mm i.d.) before measurement of absorbance at 660 nm. The calibration graph was linear for 1.6-12.8 µg/ml of p-phenylenediamine. Recoveries were 98.8-101%. Sampling frequency was 75 runs/h.