Abstract
Abstract In this work, the possibility of flow coulometry application as coulometric titration was studied. The method was used to analyze phosphates in wastewater samples. The principle of the determination consisted in the formation of molybdophosphate and its subsequent one-electron electrolytic reduction. The present method is applicable under optimal conditions in the concentration range of 1.5 × 10−6 to 5.5 × 10−5 mol/dm3. Detection limit of the method is 3.42 × 10−7 mol/dm3. Mineralization step has been proved a problem in total phosphate content determination. If mineralization was not carried out, only inorganic soluble phosphates were determined. It is a new method characterized by its simplicity of instrumentation and handling, which is a prerequisite for its further use in the field of trace analysis.
Highlights
Coulometry is based on the measurement of the electrical charge required to affect the electro chemical conversion of a studied substance
The presented method is applicable under optimal conditions in the concentration range of 1.5 × 10–6 to 5.5 × 10–5 mol/dm3 (Slana, 2001)
The measured phosphate concentrations in real wastewater samples from given sites before (1) and after (2) the treatment in a wastewater treatment plant are given in Table 1 which provides the confidence interval of phosphate concentrations determined without and with the standard addition by the flow coulometric method and the phosphate concentrations determined spectrophotometrically after mineralization according to the standard norm (STN EN ISO 6878 (757465))
Summary
Coulometry is based on the measurement of the electrical charge required to affect the electro chemical conversion of a studied substance. Snigur et al (2020) reported fast room temperature cloud point procedure for spectrophotometric determination of phosphate in water samples with linear calibration graph in the phosphate concentrations range of 1.58—63 μg/L. Orthophosphate can be determined in the linear range of 0.5—28.0 μg/L (R2 = 0.9933) with the detection limit of 0.1 μg/L and preconcentration factor of 50.
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