A model of measurement precision at low concentrations
This paper presents a model that describes the precision of measurements at low concentrations (near the limit of detection). The total variance includes both background noise, which exists even when no analyte is present and is assumed to have a fixed variance, and analytical error, which in chemical measurements is often proportional to the concentrations of the analyte. This total variance model is used to define a limit of detection and two other measures of measurement precision. These are the Characteristic Limit, which is defined as the concentration where the variances of background noise and analytical error are equal, and the Limit of Guaranteed Purity, which defines how large the true concentration might be, in light of a given measured value. Data on lead in wastewater effluent and organic chemicals in sediment are used to illustrate the calculations and demonstrate the performance of the model.
Document Type: Research Article
Publication date: 1993-09-01
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- Water Environment Research® (WER®) publishes peer-reviewed research papers, research notes, state-of-the-art and critical reviews on original, fundamental and applied research in all scientific and technical areas related to water quality, pollution control, and management. An annual Literature Review provides a review of published books and articles on water quality topics from the previous year. Published as: Sewage Works Journal, 1928 - 1949; Sewage and Industrial Wastes, 1950 - 1959; Journal Water Pollution Control Federation, 1959 - Oct 1989; Research Journal Water Pollution Control Federation, Nov 1989 - 1991; Water Environment Research, 1992 - present.
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