Spectrophotometric determination of nitrite by its catalytic effect on the oxidation of congo red with bromate

Abstract

ABSTRACT. A novel simple, sensitive and rapid kinetic-spectrophotometric method for the determination of trace amounts of nitrite is proposed. The method is based on its catalytic effect on the oxidation of congo red (CR) by potassium bromate in acidic solution. The oxidation reaction is monitored spectrophotometrically by measuring the decrease in the absorbance of CR at a suitable λmax = 570 nm for the first 10-40 s from the start of the reaction. Under the optimum experimental conditions (sulfuric acid, 0.3 M; CR, 0.75×10 -4 M; potassium bromate, 5×10-4 M and 25 o C), nitrite can be determined in the range of 0.015-0.75 µg mL −1 with the detection limit of 0.006 µg mL −1 . The relative standard deviation of five replicate determination of 0.25 µg mL −1 nitrite was 2.5%. The proposed method was applied satisfactorily to the determination of nitrite in spiked drinking water samples.

Evaluation of Water Quality of Groundwater of Sanghar District, Sindh, Pakistan: Chemical and Multivariate Analysis

“…The high concentration of nitrate-N may cause a disease commonly known as blue baby in children. High concentration of nitrite-N may cause cancer due to the formation of N-nitroso and nitrosamine compounds [38]. The application of fertilizers for irrigation and the use of detergents for washing purposes may be responsible for the higher concentration of phosphate-P in groundwater.…”

Diazo-Coupling Reactions for Spectrophotometric Estimation of Nitrite in Some Cured Meat Products

“…Due to concern potential hazards and health damage caused by nitrite to human health and aquaculture environments, most international organizations have been established sets of relative standards to limit the concentration of nitrite content in potable water, food and aquaculture. The amount of 3.0 mg/L as nitrite ion (or 0.9 mg/L as nitrite-nitrogen) was recommended by the World Health Organization (WHO) as a maximum nitrite concentration in drinking water, while the European Union limit nitrite concentration for drinking water is 0.1 mg L -1 of NO2-N. Also according to the WHO maximum allowed nitrite concentration in meat products is 200 ppm (WHO, 2011, Moldovan, 2012. While maximum amounts of nitrite to be added in different meat products at the beginning of the process and imposes a maximum residue of 50 μg/mL nitrites and 250 μg/mL nitrates in cured meat products that have not been thermally treated suggested by the current legislation (EU Directive 95/2) (Zanardi et al, 2002).…”