Extractive Photometric Determination of Nitrite in Polluted Water in ppm Level Using p-Nitroaniline and Guaiacol

Abstract

Nitrite is diazotized with p -nitroaniline in hydrochloric acid medium and coupled with guaiacol in alkaline medium to give an orange red azo dye having λ_max at 505 nm and ϵ_max =4.8 × 10⁴1. mole^ϵ1 cm⁻¹. Extraction of the dye into isopentanol shifts the absorption maxima to 540 nm and having ϵ_max =6.2x10⁴1. mole⁻¹ cm⁻¹. Beer's law is obeyed in the range of 0.12 to 0.8 ppm nitrite for aqueous system and 0.03 to 0.2 ppm for extractive system. The Sandell sensitivity for the aqueous and extractive systems were found to be 0.00095 μg cm⁻² and 0.00074 μg cm⁻² respectively. The method is applicable to polluted waters.

Key Words:

• Nitrite
• spectrophotometry
• diazotization.