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Certified reference materials for the analysis of cortisol in serum, issued by the community bureau of reference of the EEC
95
Clinica Chimica Acta, 149 (1985) 95-96
Elsevier CCA 03193
Announcement
Certified reference materials for the analysis of cortisol in serum, issued by the Community Bureau of Reference of the EEC Commission of the European Communities Directorate General for Research and Development
Cortisol is currently assayed in serum for investigation of adrenocortical function. of methods are in use for routine determinations, including fluorometric assays, competitive protein binding assays, and radioimmunoassays. Many are developed as ‘kits’. The National External Quality Assessment Schemes (NEQAS) show large differences between and within method results, in both cases amounting to more than 40%. Investigations comparing data obtained by isotope dilution-mass spectrometry with values of NEQAS, also reveal that many routine assays yield positively biased results. In order to improve both the comparability and the accuracy of cortisol determinations, serum-based reference materials with certified cortisol contents were prepared by the Community Bureau of Reference (BCR). Two pools of human serum were processed in view of producing two batches of 4,000 Amp of lyophilized serum. Bach ampoule contains the equivalent of 1.25 ml of serum. One serum pool has been spiked with pure cortisol to reach a cortisol concentration of about 750 nmol/l of serum. The cortisol analyses for certification were carried out using isotope dilution-mass spectrometry. Seven European laboratories participated in the collaborative exercise, each of them having developed its own variant of the IDMS method. Variants of the method included use of different labelled cortisols, of different gas chromatographic separation techniques, and of different mass spectrometric detections. The concentration of cortisol in the reconstituted material was certified with an uncertainty lower than 2%. Certified values are 273 and 763 nmol/l for the unspiked and spiked materials, respectively. High performance liquid chromatography and radioimmunoassays were also applied for cortisol determinations in the lyophilized materials to demonstrate the applicability of these techniques to measurement of cortisol by the user of the certified reference materials. These reference materials are to be used as calibration materials and as ‘primary’ quality control materials to evaluate routine methods. They are not intended for use as day-to-day control materials.
A variety
OW9-8981/85/%03.30 0 1985 Elsevier Science Publishers B.V. (Biomedical Division)
Each sample is delivered with a certificate and a report giving all details on the methods and results used for certification. Enquiries and orders may be sent to the following address: Community Bureau of Reference - BCR Directorate General XII Commission of the European Communities 200, rue’de la Loi B-1049 Brussels Belgium
Clinica Chimica Acta, 149 (1985) 95-96
Elsevier CCA 03193
Announcement
Certified reference materials for the analysis of cortisol in serum, issued by the Community Bureau of Reference of the EEC Commission of the European Communities Directorate General for Research and Development
Cortisol is currently assayed in serum for investigation of adrenocortical function. of methods are in use for routine determinations, including fluorometric assays, competitive protein binding assays, and radioimmunoassays. Many are developed as ‘kits’. The National External Quality Assessment Schemes (NEQAS) show large differences between and within method results, in both cases amounting to more than 40%. Investigations comparing data obtained by isotope dilution-mass spectrometry with values of NEQAS, also reveal that many routine assays yield positively biased results. In order to improve both the comparability and the accuracy of cortisol determinations, serum-based reference materials with certified cortisol contents were prepared by the Community Bureau of Reference (BCR). Two pools of human serum were processed in view of producing two batches of 4,000 Amp of lyophilized serum. Bach ampoule contains the equivalent of 1.25 ml of serum. One serum pool has been spiked with pure cortisol to reach a cortisol concentration of about 750 nmol/l of serum. The cortisol analyses for certification were carried out using isotope dilution-mass spectrometry. Seven European laboratories participated in the collaborative exercise, each of them having developed its own variant of the IDMS method. Variants of the method included use of different labelled cortisols, of different gas chromatographic separation techniques, and of different mass spectrometric detections. The concentration of cortisol in the reconstituted material was certified with an uncertainty lower than 2%. Certified values are 273 and 763 nmol/l for the unspiked and spiked materials, respectively. High performance liquid chromatography and radioimmunoassays were also applied for cortisol determinations in the lyophilized materials to demonstrate the applicability of these techniques to measurement of cortisol by the user of the certified reference materials. These reference materials are to be used as calibration materials and as ‘primary’ quality control materials to evaluate routine methods. They are not intended for use as day-to-day control materials.
A variety
OW9-8981/85/%03.30 0 1985 Elsevier Science Publishers B.V. (Biomedical Division)
Each sample is delivered with a certificate and a report giving all details on the methods and results used for certification. Enquiries and orders may be sent to the following address: Community Bureau of Reference - BCR Directorate General XII Commission of the European Communities 200, rue’de la Loi B-1049 Brussels Belgium