Linear calibrations in chromatography: the incorrect use of ordinary least squares for determinations at low levels, and the need to redefine the limit of quantification with this regression model
dc.contributor.author
dc.date.accessioned
2021-05-21T11:36:06Z
dc.date.available
2022-10-28T05:46:32Z
dc.date.issued
2020-07-01
dc.identifier.issn
1615-9306
dc.identifier.uri
dc.description.abstract
Ordinary least squares is widely applied as the standard regression method for analytical calibrations, and it is usually accepted that this regression method can be used for quantification starting at the limit of quantification. However, it requires calibration being homoscedastic and this is not common. Different calibrations have been evaluated to assess whether ordinary least squares is adequate to quantify estimates at low levels. All calibrations evaluated were linear and heteroscedastic. Despite acceptable values for precision at limit of quantification levels were obtained, ordinary least squares fitting resulted in significant and unacceptable bias at low levels. When weighted least squares regression was applied, bias at low levels were solved and accurate estimates were obtained. With heteroscedastic calibrations, limit values determined by conventional methods are only appropriate if weighted least squares is used. A 'practical limit of quantification' can be determined with ordinary least squares in heteroscedastic calibrations, which should be fixed at a minimum of 20 times the value calculated with conventional methods. Biases obtained above this 'practical limit' were acceptable applying ordinary least squares and no significant differences were obtained between the estimates measured using weighted and ordinary least squares when analyzing real-world samples
dc.format.extent
10 p.
dc.format.mimetype
application/pdf
dc.language.iso
eng
dc.publisher
Wiley-VCH Verlag
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Versió postprint del document publicat a: https://doi.org/10.1002/jssc.202000094
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© Journal of Separation Science, 2020, vol. 43, núm. 13, p. 2708-2717
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Articles publicats (D-Q)
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Tots els drets reservats
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Sánchez Navarro, Juan Manuel 2020 Linear calibrations in chromatography: the incorrect use of ordinary least squares for determinations at low levels, and the need to redefine the limit of quantification with this regression model Journal of Separation Science 43 13 2708 2717
dc.subject
dc.title
Linear calibrations in chromatography: the incorrect use of ordinary least squares for determinations at low levels, and the need to redefine the limit of quantification with this regression model
dc.type
info:eu-repo/semantics/article
dc.rights.accessRights
info:eu-repo/semantics/openAccess
dc.embargo.terms
2021-07-01T00:00:00Z
dc.date.embargoEndDate
info:eu-repo/date/embargoEnd/2021-07-01
dc.type.version
info:eu-repo/semantics/acceptedVersion
dc.identifier.doi
dc.identifier.idgrec
032674
dc.type.peerreviewed
peer-reviewed
dc.identifier.eissn
1615-9314