Simultaneous determination of O- and P-nitrophenol by first derivative spectrophotometry

A simple method by first derivative spectrophotometry is proposed for the s imultaneous determination of o-nitrophenol and p-nitrophenol. The analytes were separated from samples by liquid-liquid extraction (pH = 7.4) as tetra butylammonium ion pairs into the 1,2-dichloroethane organic phase and subse quently the extracts were evaluated directly by derivative spectrophotometr y. Simultaneous determination of both analytes could be carried out using t he zero-crossing and the graphical methods for o-nitrophenol and p-nitrophe nol, respectively. The determination ranges were found to be between 0.115 to 3.00 ppm and 0.130 to 3.00 ppm for o-nitrophenol and p-nitrophenol, resp ectively. The relative standard deviations were in all instances less than 2.0%. The proposed method was applied to the determination of these compoun ds in fruit juices.