FLAME-PHOTOMETRIC DETERMINATION OF SULFATE IONS IN WATER USING ULTRASOUND

The use of ultrasound in the flame-photometric determination of sulfate-ions in water by the indirect potassium method was studied. At the same time, precipitation of sulfate ions was carried out with an excess of slightly soluble dry potassium barium phosphate salt. It is shown that the amount of potassium that has passed into the solution is proportional to the amount of sulfate ions in the analyzed sample. To improve the reproducibility and correctness of the obtained results, as well as to increase the expressivity of the analysis, the precipitation of sulfate ions was carried out under the influence of ultrasound with a frequency of 5.0 - 7.0 MHz, an intensity of 3.0 - 5.0 W/cm2 for a period of time ≥ 2,0 min. A method for determining sulfate ions in waters with mineralization up to 50 g/l has been developed, the range of determined concentrations of sulfate ions is 10 – 150 mg/l. The correctness of the obtained results (determined using standard water samples UkrNDIsil CRM 022.3-20s, CRM 022.3-20m and CRM 022.3-20vm) was for water with mineralization of 50 g/l - 92.5 - 93.1%, and for water with mineralization up to 10 g/l - 99.2 - 99.6%. The relative standard deviation of the analysis results did not exceed 0.051. Without the use of ultrasound, the quantitative determination of the content of sulfate ions is possible only in waters with mineralization up to 10 g/l with an accuracy of 90.2 - 91.0%.