Limit of blank, limit of detection and limit of quantitation.
01 Aug 2008-Vol. 29
TL;DR: The Limit of Blank, Limit of Detection, and Limit of Quantitation are terms used to describe the smallest concentration of a measurand that can be reliably measured by an analytical procedure.
Abstract: * Limit of Blank (LoB), Limit of Detection (LoD), and Limit of Quantitation (LoQ) are terms used to describe the smallest concentration of a measurand that can be reliably measured by an analytical procedure. * LoB is the highest apparent analyte concentration expected to be found when replicates of a blank sample containing no analyte are tested. LoB = mean(blank) + 1.645(SD(blank)). * LoD is the lowest analyte concentration likely to be reliably distinguished from the LoB and at which detection is feasible. LoD is determined by utilising both the measured LoB and test replicates of a sample known to contain a low concentration of analyte. * LoD = LoB + 1.645(SD (low concentration sample)). * LoQ is the lowest concentration at which the analyte can not only be reliably detected but at which some predefined goals for bias and imprecision are met. The LoQ may be equivalent to the LoD or it could be at a much higher concentration.
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TL;DR: The presented review provides information relating to the calculation of the limit of detection and limit of quantitation.
Abstract: The quality of an analytical method developed is always appraised in terms of suitability for its intended purpose, recovery, requirement for standardization, sensitivity, analyte stability, ease of analysis, skill subset required, time and cost in that order. It is highly imperative to establish through a systematic process that the analytical method under question is acceptable for its intended purpose. Limit of detection (LOD) and limit of quantification (LOQ) are two important performance characteristics in method validation. LOD and LOQ are terms used to describe the smallest concentration of an analyte that can be reliably measured by an analytical procedure. There has often been a lack of agreement within the clinical laboratory field as to the terminology best suited to describe this parameter. Likewise, there have been various methods for estimating it. The presented review provides information relating to the calculation of the limit of detection and limit of quantitation. Brief information about differences in various regulatory agencies about these parameters is also presented here.
2,264 citations
Cites background from "Limit of blank, limit of detection ..."
...[2] Comparison of regulatory authorities such as United States Pharmacopoeia (USP),[3] Foods and Drugs Administration (FDA),[4] International Union of Pure and Applied Chemistry (IUPAC),[5] International Conference on Harmonisation (ICH)[6] and Association of Analytical Communities (AOAC)[7,8] for limit of detection and limit of quantitation are produced in Tables 1 and 2, respectively....
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TL;DR: This basic guide will help to orient beginners and users of qPCR in the use of this powerful technique.
Abstract: Real time PCR (quantitative PCR, qPCR) is now a well-established method for the detection, quantification, and typing of different microbial agents in the areas of clinical and veterinary diagnostics and food safety. Although the concept of PCR is relatively simple, there are specific issues in qPCR that developers and users of this technology must bear in mind. These include the use of correct terminology and definitions, understanding of the principle of PCR, difficulties with interpretation and presentation of data, the limitations of qPCR in different areas of microbial diagnostics and parameters important for the description of qPCR performance. It is not our intention in this review to describe every single aspect of qPCR design, optimization, and validation; however, it is our hope that this basic guide will help to orient beginners and users of qPCR in the use of this powerful technique.
494 citations
Cites methods from "Limit of blank, limit of detection ..."
...The LOQ was defined as the smallest amount of analyte, which can be measured and quantified with defined precision and accuracy under the experimental conditions by the method under validation (Armbruster and Pry, 2008; Anonymous, 2011, 2013)....
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TL;DR: This review describes the analytical requirements for a robust clinical biomarker assay, including concepts of precision, trueness, specificity and analytical interference, and carryover, and introduces the clinical considerations of diagnostic accuracy, receiver operating characteristic analysis, positive and negative predictive values, and clinical utility.
Abstract: Tremendous efforts have been made over the past few decades to discover novel cancer biomarkers for use in clinical practice. However, a striking discrepancy exists between the effort directed toward biomarker discovery and the number of markers that make it into clinical practice. One of the confounding issues in translating a novel discovery into clinical practice is that quite often the scientists working on biomarker discovery have limited knowledge of the analytical, diagnostic, and regulatory requirements for a clinical assay. This review provides an introduction to such considerations with the aim of generating more extensive discussion for study design, assay performance, and regulatory approval in the process of translating new proteomic biomarkers from discovery into cancer diagnostics. We first describe the analytical requirements for a robust clinical biomarker assay, including concepts of precision, trueness, specificity and analytical interference, and carryover. We next introduce the clinical considerations of diagnostic accuracy, receiver operating characteristic analysis, positive and negative predictive values, and clinical utility. We finish the review by describing components of the FDA approval process for protein-based biomarkers, including classification of biomarker assays as medical devices, analytical and clinical performance requirements, and the approval process workflow. While we recognize that the road from biomarker discovery, validation, and regulatory approval to the translation into the clinical setting could be long and difficult, the reward for patients, clinicians and scientists could be rather significant.
357 citations
Cites background from "Limit of blank, limit of detection ..."
...from the mean plus two (or three) SDs [18,25,46]....
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...A performance indicator that incorporates these requirements is the limit of quantitation (LoQ), the lowest concentration at which the analyte can not only be reliably distinguished from zero but also meets certain specifications for bias and precision [46,48]....
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...After determining the mean and SD of the results, the LoD is then calculated from the mean plus two (or three) SDs [18,25,46]....
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TL;DR: This work presents methods to determine the limit of detection (LoD) and thelimit of quantification (LoQ) as applicable to qPCR, based on standard statistical methods as recommended by regulatory bodies adapted toqPCR and complemented with a novel approach to estimate the precision of LoD.
347 citations
TL;DR: A literature search was performed using MEDLINE/PubMed and scientific congress databases using the terms ‘BRAF,’ ‘mutation, and ‘cancer/tumor.’ These results were filtered to include diagnostic tests for determining BRAF mutation status as mentioned in this paper.
290 citations
References
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TL;DR: The statistically determined LOD and LOQ values for these assays underestimated the LOD because of the large imprecision associated with blank measurements and the inability of blank samples to meet typical GC-MS acceptance criteria.
Abstract: The limit of detection (LOD) for any analytical procedure, the point at which analysis is just feasible, may be determined by a statistical approach based on measuring replicate blank (negative) samples or by an empirical approach, consisting of measuring progressively more dilute concentrations of analyte. The limit of quantitation (LOQ), or concentration at which quantitative results can be reported with a high degree of confidence, may likewise be determined by either approach. We used both methods to determine LOD and LOQ for forensic gas chromatographic-mass spectrometric (GC-MS) analyses of abused drugs. The statistically determined LOD and LOQ values for these assays underestimated the LOD because of the large imprecision associated with blank measurements and the inability of blank samples to meet typical GC-MS acceptance criteria. The empirical method provided much more realistic LOD values, supported by reasonable experimental data, and are 0.5-0.03 the magnitude of the corresponding statistical LODs. The empirical LODs and LOQs are identical for these GC-MS assays. The observations made here about the LOD/LOQ for specific forensic GC-MS procedures are generally applicable to any type of analysis.
442 citations
01 Jan 2004
TL;DR: NCCLS document EP17-A—Protocols for Determination of Limits of Detection and Limits of Quantitation; Approved Guideline provides protocols for determining the lower limit of detection of clinical laboratory methods, for verifying claimed limits, and for the proper use and interpretation of these limits.
Abstract: NCCLS document EP17-A—Protocols for Determination of Limits of Detection and Limits of Quantitation; Approved Guideline provides protocols for determining the lower limit of detection of clinical laboratory methods, for verifying claimed limits, and for the proper use and interpretation of these limits. This document also provides guidance for determining lower limits of quantitation based on a laboratory’s goals for performance at low-levels. This applies to all quantitative procedures, even if the reported result is qualitative. EP17-A is intended for use by clinical laboratories and by manufacturers of in vitro diagnostic tests. NCCLS. Protocols for Determination of Limits of Detection and Limits of Quantitation; Approved Guideline. NCCLS document EP17-A (ISBN 1-56238-551-8). NCCLS, 940 West Valley Road, Suite 1400, Wayne, Pennsylvania 19087-1898 USA, 2004. THE NCCLS consensus process, which is the mechanism for moving a document through two or more levels of review by the healthcare community, is an ongoing process. Users should expect revised editions of any given document. Because rapid changes in technology may affect the procedures, methods, and protocols in a standard or guideline, users should replace outdated editions with the current editions of NCCLS documents. Current editions are listed in the NCCLS Catalog, which is distributed to member organizations, and to nonmembers on request. If your organization is not a member and would like to become one, and to request a copy of the NCCLS Catalog, contact the NCCLS Executive Offices. Telephone: 610.688.0100; Fax: 610.688.0700; E-Mail: exoffice@nccls.org; Website: www.nccls.org
232 citations
TL;DR: The following Special Report from the Committee on Nomenclature of the American Thyroid Association is an attempt to clarify some of the confusion that exists on the use and performance of the many various methods for free thyroxin (FT4) and to update the performance guidelines of the newer “highly sensitive" thyrotropin (TSH) sandwich-type assays.
Abstract: The following Special Report from the Committee on Nomenclature of the American Thyroid Association (A TA) is an attempt to clarify some of the confusion that exists on the use and performance of the many various methods for free thyroxin (FT4) and to update the performance guidelines of the newer “highly sensitive” thyrotropin (TSH) sandwich-type assays. In 1987, the ATA through this Committee published a report on the recommended nomenclature for tests of thyroid hormone assessment. This was followed in 1990 by a second report recommending to clinicians the proper thyroid test algorithm for thyroid disease screening. This third report now clarifies some of the issues and concerns regarding the different options for FT4 methods and discusses the committee’s consensus and guidelines regarding the utility of the newest, so-called third-generation “sensitive” TSH assays. Timely reports such as these are important contributions that help dispel the confusion that laboratorians have regarding which test approach is best and what are the experts’ opinions concerning appropriate clinical utility. This report also exemplifies the cooperative spirit that currently exists between the ATA and the AACC. Three of the current members of the ATA Commission on Nomenclature are AACC members. it is important that provoking, penetrating consensus reports on specific analytes continue to appear from time to time. As with the consensus document published several years ago on cyclosporine monitoring, these reports are very useful to laboratory directors in their decisions on which tests are most efficient and appropriate for a particular clinical setting and what guidelines should be followed to ensure acceptable test performance. The authors of this special report are .to be commended for their effort in clarifying a somewhat muddied topic.
118 citations
TL;DR: The limits of linearity (LOL) and detection (LOD) are important factors in establishing the reliability of an analytical procedure for accurately assaying drug concentrations in urine specimens.
Abstract: The limits of linearity (LOL) and detection (LOD) are important factors in establishing the reliability of an analytical procedure for accurately assaying drug concentrations in urine specimens. Multiple analyses of analyte over an extended range of concentrations provide a measure of the ability of the analytical procedure to correctly identify known quantities of drug in a biofluid matrix. Each of the seven drugs of abuse gives linear analytical responses from concentrations at or near their LOD to concentrations several-fold higher than those generally encountered in the drug screening laboratory. The upper LOL exceeds the Department of Navy (DON) cutoff values by factors of approximately 2 to 160. The LOD varies from 0.4 to 5.0% of the DON cutoff value for each drug. The limit of quantitation (LOQ) is calculated as the LOD + 7 SD. The range for LOL is greater for drugs analyzed with deuterated internal standards compared with those using conventional internal standards. For THC acid, cocaine, PCP, and morphine, LOLs are 8 to 160-fold greater than the defined cutoff concentrations. For the other drugs, the LOL's are only 2 to 4-fold greater than the defined cutoff concentrations.
39 citations
36 citations