SPECTROPHOTOMETRIC DETERMINATION OF NITRITE IN WATER SAMPLES USING RESPONSE SURFACE METHODOLOGY

The purpose of this paper is to develop a simple and inexpensive method for spectrophotometric determination of nitrite based on its diazotization-coupling reaction with 4-amino-3-hydroxynaphthalene-1-sulfonic acid (AHNSA) at 0.00076 mol L-1 and 1-Naphthylamine (1-NA) at 0.001 mol L-1 in hydrochloric acid at 1.0 mol L-1. The behaviour of several parameters that affect the reaction, such as hydrochloric acid concentration, AHNSA, and 1-NA, was examined using central composite design (CCD) as a response surface method. Beer's law was found to be followed at 347 and 394 nm in two concentration ranges of nitrite: 0.01-0.90 mg L1 and 1.0-8.5 mg L1. The method was used to determine nitrite at low mg L1 levels in rain, tap, and wastewater samples with satisfactory statistics. The RSD in determining nitrite in genuine samples is less than 10%.

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