Determination of Trace Nitrite Amounts in Soil by Developed Cloud Point Extraction-Spectrophotometry Method

Abstract

A new and simple method for the selective and sensitive determination of trace amounts of nitrite in soil samples is developed by a combination of cloud point extraction (CPE) and spectrophotometry technique. The procedure is based on the Griess reaction on 3,3`-dimethyl benzidine with nitrite in the presence of 1-naphthol in acidic media to form a yellow diazo dye, which shows absorption at lambda max 455nm. The formation of colored diazo dye is followed by extraction into the Triton X-114rich phase. Cloud point extraction method parameters such as surfactant amount, temperature, and incubation time are evaluated and optimized. The results obtained showed a very good linear range of 10-1250 µgL -1 , with good regression coefficients (R 2 ) ≥ 0.9997 and a preconcentration factor of 12.5. The limit of detection (LOD) describes as 3SDblank/m, and the quantification limit (LOQ) describes as 10SDblank/m, where m is the slope of the calibration curve and they are equal to 7.50 and 22.71 µgL -1 respectively. The recommended method can apply to determine the ultra-trace amount of nitrite in soil samples.