Uncertainty of measurement for determination of major elements in iron ore using ICP-OES

Abstract

Quality of analytical results (chemical metrology) is a major issue in industry as important decisions are often made based on these results which affect production process, trade, healthcare, and societal problems. For a long time it is observed that chemical analysis provided by different organizations for the same sample vary significantly. The variation is also observed within the same organization when the analysis is performed by different people, leading to ambiguity of the produced values. The uncertainty of a measurement is a parameter, associated with the result of a measurement that characterizes the dispersion of true values, which could reasonably be attributed to the measurand. The parameter may be the standard deviation (or a given multiple of it) or the half width of an interval having stated level of confidence. Efforts have been made to evaluate the uncertainty arising from the iron ore during the process of sample preparation and analysis using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). Quantitative analysis of ICP-OES results of iron ore comprises influence of all possible sources and factors of uncertainty including sample preparation technique, measurement principle, analyte concentration, matrix properties etc. Uncertainty evaluation is not a simple task because of peculiarities of chemical measurement. The chemical parameters always are transformed into physical parameters (intensity measurement) and only then this value is measured. The present paper discusses quantitative evaluation of chemical analysis of major elements in iron ore and its impact on uncertainty of measurement results in ICP-OES.