SPECTROPHOTOMETRIC DETERMINATION OF NITRITE IN WATER SAMPLES USING RESPONSE SURFACE METHODOLOGY
MASOUD SHARIATI-RAD *
Department of Analytical Chemistry, Faculty of Chemistry, Razi University, Kermanshah, Iran
MOHSEN IRANDOUST
Department of Analytical Chemistry, Faculty of Chemistry, Razi University, Kermanshah, Iran
SHABNAM MOHAMMADI
Department of Analytical Chemistry, Faculty of Chemistry, Razi University, Kermanshah, Iran
*Author to whom correspondence should be addressed.
Abstract
The present paper seeks to develop a simple and economical method for the spectrophotometric determination of nitrite based on its diazotization-coupling reaction with 4-amino-3-hydroxynaphthalene-1-sulfonic acid (AHNSA) with concentration of 0.00076 mol L-1 and 1-Naphthylamine (1-NA) with concentration of 0.001 mol L-1 in hydrochloric acid with concentration of 1.0 mol L-1. The behavior of various factors which affect the reaction i.e. concentration of hydrochloric acid, AHNSA and 1-NA were investigated by central composite design (CCD) as a response surface method. Beer's law was found to be followed in two concentration range of nitrite as 0.01-0.90 mg L−1 and 1.0-8.5 mg L−1 at 347 and 394 nm, respectively. The approach was applied to determine nitrite at low mg L−1 levels with satisfactory statistics in rain, tap and wastewater samples. The RSD in determination of nitrite in real samples is lower than 10%.
Keywords :
Keywords: Nitrite, spectrophotometric, 4-amino-3-hydroxynaphthalene-1-sulfonic acid, 1-Naphthylamine, central composite design