Development of a certified reference material intended to control measurement results accuracy of petroleum products in water and its application for proficiency testing of laboratories through interlaboratory comparative tests

Abstract

The article considers the notion of oil content as a measurable indicator and provides information on the procedures for measuring the content of petroleum products by IR spectrometry in natural water, drinking water, and treated wastewater. Certified reference materials (CRMs) for petroleum products with certified characteristics of the mass or mass concentration of petroleum products in the matrix were registered in the system of metrological support of measurements. The content of polar petroleum products in the raw material was not taken into account when establishing the certified values of these CRMs; this leads to a significant difference between a certified characteristic of CRMs and the determined indicator of measurement procedures based on the IR spectrometry method. In contrast to CRMs with a certified characteristic in the form of the total content of petroleum products, there was a need to develop CRM for determining the mass concentration of only non-polar and low-polar petroleum products by the IR spectrometry method.Information about the stages of CRM development is presented: selection and preparation of material, investigation of material stability. The results of CRM certification for certified indicators in the range of 0.05–2.00 mg/dm3 are presented. The correctness of these results was confirmed in accredited laboratories by interlaboratory comparative tests.The CRM of mass concentration of non-polar petroleum products in a polar organic solvent GSO 11733–2021 was approved. The metrological characteristics of the CRM were established: the range of permissible certified values is 0.1–3.0 mg/cm3, the permissible relative expanded uncertainty of the certified value for k=2 5 %. The traceability to SI units of the certified CRM value is insured.It has been confirmed that the developed GSO 11733–2021 is intended to control the accuracy of the measurement results of the mass concentration of non-polar petroleum products in drinking water, natural surface water, and treated wastewater using IR spectrometry and can be used for attestation of procedures for measuring the mass concentration of non-polar petroleum products in water by IR spectrometry. The scope of the CRM is environmental protection, quality control of drinking water, natural surface water, and treated wastewater.