Clinical Chemistry · 1986 · 16 citations · 0 references
Natural SciencesChemistryEndocrinologyAnalytical ChemistryGood Laboratory PracticeMass Spectrometric AnalysisAnalytical MeasurementsEndocrine AssessmentEndocrine DiagnosticsEndocrine TestingHormonal EvaluationMass SpectrometryExternal Quality InspectionIsotope DilutionIsotope Dilution Mass SpectrometryMass Spectrometric Hormone AnalysisMass Spectrometric QuantificationMass Spectrometry In Endocrine TestingMass Spectrometry-based Hormone AnalysisSerum Cortisol Measurement
Isotope dilution and mass spectrometry were used in two independent laboratories to determine cortisol in 15 plasma and serum pools used in the British and German national schemes for the external quality assessment of routine assays. For the concentration range 240-700 nmol/L, differences between the data obtained by the two laboratories were generally less than 4% but were approximately 7% in two instances. The discrepancies are nevertheless small in comparison with the bias observed for many routine assays.