Spectrophotometric determination of hydroxylamine and nitrite in mixture in water and biological samples after micelle-mediated extraction.

Hydroxylamine (HA)1 and nitrite recycle through the hydrosphere as a result of microbial processes [1–3]. These compounds are important intermediates in the biological nitrogen cycle and are present in soils and surface waters [4,5]. The important role of nitrite in producing N-nitrosamines, some of which have been shown to be carcinogens in the human body, is well established. Nitrite is also a versatile chemical agent that has found numerous applications ranging from dye manufacture to food preservation [6]. HA is often used as a raw material for the synthesis of pharmaceutical intermediates and Wnal drug substances. Modest levels of HA can be toxic to humans, animals, and even plants [7]. The need for selective and sensitive methods for determination of these compounds is well documented. Several methods have been reported for the spectrophotometric determination of HA and nitrite [8–14]. To the best of our knowledge, there is no report on the determination of HA and nitrite in mixtures. In this work, we present a spectrophotometric determination method for resolving nitrite and HA mixtures after cloud point extraction (CPE). The method is based on the combination of two well-known reactions: oxidation of HA to nitrite and nitrite determination with N,N-dimethylaniline and p-nitroaniline followed by micelle-mediated extraction of the produced azo dye. The nonionic surfactant Triton X-114 was chosen as the extraction agent. A PerkinElmer Lambda 45 UV/Vis spectrometer was used for recording absorbance spectra. Absorption measurements at Wxed wavelength were performed using a Shi-