Kinetic-spectrophotometric determination of trace amounts of resorcinol based on its inhibitory effect on the formaldehyde catalyzed reaction betweenbromate and neutral red

A novel sensitive, simple and fast kinetic method for the determination of trace amounts of resorcinol (0.50-3.00 mu g ml(-1)) based on its inhibitory effect on the formaldehyde catalyzed oxidation reaction of neutral red by bromate ion in acidic media is reported. The reaction is monitored spectrop hotometrically by measuring the decrease in the absorbance of neutral red i n an inhibited reaction at 524 mm using a variable - time method. The detec tion limit is 0.38 mu g ml(-1) and the relative standard deviation of ten r eplicate measurements for 1 mu g ml(-1) of resorcinol is 4.2%.The procedure was successfully applied to the determination of resorcinol in resorcinol- S topical cream.