Introduction of a spectrophotometric method for simultaneous determination of nitrite and nitrate in water samples using partial least squares

Abstract

A simple and sensitive spectrophotometric method for simultaneous determination of nitrite and nitrate was introduced. The method is based on the reaction of nitrite and nitrate with 2,4-xylenol as reagent in the concentrated sulfuric acid. Calibration curves were linear in the range of 0.2-20.0 and 0.5-7.0 mg L -1 for nitrite and nitrate, respectively. Due to the severe spectral overlapping of the reaction products of two anions with 2,4-xylenol, partial least squares (PLS) was used for simultaneous determination of nitrite and nitrate in the mixtures. For calibration and validation, 25 binary mixtures of nitrite and nitrate (17 calibration and eight external test samples) were designed by simplex lattice design with lattice degree of one. PLS models with Q 2 values of 0.988 and 0.976 were constructed for nitrite and nitrate, respectively. The validated models were used to analyze real water samples. With the recommended method, simultaneous determination of nitrite and nitrate in water samples is possible with satisfactory results.

The determination of nitrite by a graphene quantum dot fluorescence quenching method without sample pretreatment

“…It has the advantages of a good separating effect and high speed, but needs complex sample pre‐treatment processes, and therefore is not suitable for analysing large amounts of samples. Spectrophotometry is another method in the National Standard for analysing nitrite, it is simple and suitable for batch sample analysis, but the method sensitivity needs improvement and the chromogenic reagent commonly used has a some toxicity. Chemiluminescence (CL) based on the microfluidic chip is also an effective way for the sensing nitrite, but this option is reagent‐ and time‐consuming when needed for large quantities of data.…”

Simultaneous Determination of Mixtures of Nitrite and Nitrate by Reversed‐Phase Ion‐Pair Liquid Chromatography

“…The determination of nitrate and nitrite is of increasing interest. A variety of analytical methods for the simultaneous determination of nitrate and nitrite have been developed recently, including spectroscopic methods, capillary electrophoresis, and chromatography . The advantage of spectroscopic determination is that it involves less complication; however, spectrophotometric procedures are highly prone to interferences.…”