Determination of trace potassium permanganate in tap water by solid phase extraction combined with spectrophotometry

A simple solid phase extraction (SPE) coupled with spectrophotometric method was developed for determination of trace permanganate (MnO4-) in water. Commercial reagent polyamined-6 powder was used as SPE stationary phase to retain MnO4- which is based on the fact that MnO4- can be adsorbed on polyamide 6 (PA-6) sorbent as water samples flow through the SPE cartridge. 3,3 ',5,5 '-tetramethylbenzidine (TMB) were used both as eluent solution and chromo-genic agent to convert the adsorbed MnO4- into Mn2+ and generate blue oxidized product with high molar absorptivity. Quantification of MnO4- could be obtained by spectrophotometric detection of the resulting solution flow out of the SPE cartridge. The extraction and detection variables was optimized to maximize the absorbance of the TMB oxidized product. Under opti-mized conditions, this method provided linear dynamic ranges of 0.01-1 mu mol L-1 for MnO4- with preconcentration of 100 mL water sample. The limits of detection (3Sb/m) of this method in deionized water were calculated to be 5.1 nM, and the relative standard deviations were deter-mined to be 3.2% (C = 0.1 mu mol L-1, n = 5). This method has been applied to the determination of MnO4- in spiked tap waters and satisfactory recovery was obtained.