Determination of NO2- ions using spectrophotometry
Dosing principle
In the presence of dichloride of N-(naphtyl-1) diamino-1,2 ethane at pH 1.9 there is a diazotization reaction of amino-4 benzenesulfonamide by the nitrites. The pink complex created is measured spectrophotometrically at a wavelength close to 540 nm.
A calibration line is used to relate the absorbance to the nitrite concentration.
Refer to the calibration sheet
Precautions for use: Filtering the water before dosing is preferable since the presence of suspended matter is capable of falsifying the colorimetric measurement.