Uncertainty Evaluation and Method Improvement for Determination of Cl-,SO42-in Oilfield Water by Ion Chromatography
Ion chromatography simplifies the process of measuring inorganic ions in oilfield water,delivering accurate results.This method is extensively employed in testing labs within the oilfield chemical sector.Nonetheless,the testing phase invariably introduces certain uncertainties.In compliance with CNAS-CL01:2018,which sets forth the"Criteria for Accreditation of Testing and Calibration Laboratories",it's imperative for labs to assess the measurement uncertainty.This study,adhering to CNAS-GL006:2019's"Guidance on the Evaluation of Uncertainty in Chemical Analysis",devises an uncertainty evaluation method for Cl-and SO42-content measurement in oilfield water using ion chromatography.Following the protocols outlined in SY/T 5523-2016 for oilfield water analysis(sampling,transport,and preservation)and GB/T 14642-2009 for determining Cl-and SO42-in such water via ion chromatography,we establish a measurement model.This involves identifying uncertainty sources,assessing each uncertainty component,and calculating the combined standard uncertainty.The findings for the oilfield water samples,within a 95%confidence interval,reveal Cl-levels at(10.99±0.10)mg·L-1 and SO42-levels at(14.05±0.08)mg·L-1.The key to enhancing the precision of these measurements lies in addressing the significant relative standard uncertainties encountered during standard solution preparation and the repeatability of parallel sample testing.
ion chromatographyoilfield water analysis methoduncertaintyCl-SO42-
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