Optical-emission spectrometry method with inductively coupled plasma for determining the mass concentration of phosphorus in an oil-water emulsion

Abstract

A method for determining the mass concentration of phosphorus in a water-oil emulsion used for wire drawing by inductively coupled plasma optical emission spectrometry has been developed. Phosphorus enters the emulsion after etching the wire in a solution of orthophosphoric acid, which removes oxides that have appeared in the process of forming brass. It is one of the determined indicators that additionally characterizes the state of the emulsion during operation. This creates an insoluble phosphate film. The resulting phosphate film layer should not be too thick, as it has a negative effect on further processing (an additional factor of contamination of the emulsion on thin drawing). The most promising method for determining harmful impurities in an emulsion, including phosphorus, is optical emission spectrometry with inductively coupled plasma. The method is based on the sputtering of the analyzed sample in an argon plasma excited by a high-frequency electromagnetic field. To determine the mass concentration of phosphorus, it is necessary to perform calibration of the inductively coupled plasma spectrometer. To check the correctness of the calibration, a control sample is used, which is prepared from the state standard sample (SSS) of the composition of an aqueous solution of phosphate ions. Next, it is necessary to prepare working samples of solutions of water-oil emulsion. Then, the mass concentration of phosphorus in the analyzed sample is measured using an inductively coupled plasma optical emission spectrometer Ultima Expert (HORIBA, France). Accuracy indicators, extended uncertainty of measurement results for the method are calculated in accordance with STB ISO 5725-2.