References
- Buttner J, Borth R, Boutwell JH, Broughton PMG, Bowyer RC. IFCC: Approved recommen-dation (1983) on quality control in clinical chemistry. Part 5. External quality control. Expert panel on nomenclature and principles of quality control in clinical chemistry. J Clin Chem Clin Biochem 1983; 21: 885–92.
- International Organization for Standardization. ISO guide 43–1, proficiency testing by interlabora-tory comparisons. Part 1: Development and operation of proficiency testing schemes. ISO, Geneva: 1997.
- Orenmark U, Uldall A, Van Nevel L, Aregbe Y, Taylor PDP. IMEP-17 trace and minor constitu-ents in human serum. Certification report. Report EUR 20243 EN, IRMM, Geel, September 2002, www.imep.ws
- IMEP-17 trace and minor constituents in human serum. Report to participants. Part 1. Interna-tional comparability (Van Nevel L, Ornemark U, Smeyers P, Harper C, Taylor PDP, Report EUR 20657 EN). Part 2. Methodology and quality specifications (Ornemark U, Van Nevel L, Smeyers P, Harper C, Taylor PDP. Report EUR 20694 EN). Part 3. Overview of national results an Nevel L, Ornemark U, Smeyers P, Harper C, Taylor PDP. Report EUR 20768 EN). IRMM, Geel, June 2003, www.imep.ws
- Directive 98/79/EC of the European parliament and of the Council of 27 Oct. 1998 on in vitro diagnostic medical devices, Official Journal of the European Communities, L 331/1, 7 Dec. 1998.
- Pedersen MM, Ornemark U, Rustad P, Steensland H, Loikkanen M, Olafsdottir E, Henriksen GM, Jorgensen N, Uldall A, Nordin G, Nordberg U-R. The Nordic trueness project 2002. Report to participants. EQAnord Report, 28 Sept. 2003.
- Uldall A, Nielsen GM, Jorgensen N, Loikkanen M, Steensland H, Nordin G, Olafsdottir E, Ornemark U, Keindnen M. Nordberg U-R EQAnews 2002; 13: 7–9.
- Rustad P, Felding P, Franzson L, Kairisto V, Lahti A, MATtensson M, Hyltoft Petersen P, Simonsson S, Steensland H, Uldall A. The Nordic Reference Interval Project 2000 (NORIP): recommended reference intervals for 25 common biochemical properties Scand J Clin Lab Invest 2004; 64: 271–84.
- Ross JW, Miller WG, Myers GL, Praestgaard J. The accuracy of laboratory measurements in clinical chemistry: a study of 11 routine chemistry analytes in the College of American Pathologists Chemistry survey with fresh frozen serum, defini-tive and reference methods. Arch Pathol Lab Med 1998; 122: 587–608.
- Thienpont LM, Stöckl D, FriedeckST B, Kratochvila J, Budina M. Trueness verification in European external quality assessment schemes. Time to care about the quality of the samples. Scand J Clin Lab Invest 2003; 63: 195–201.
- Henriksen GM, Pedersen MM, Norgaard I, Blom M, Blou L, Blaabjerg 0, Uldall A. Minimally processed fresh frozen human reference sera: preparation, testing, and application to interna-tional external quality assurance. Scand J Clin Lab Invest 2004; 64: 293–308.
- Scandinavian Society of Clinical Chemistry. Certificate of analysis. NFKK reference serum X, Clinical components in human serum, Lot number: NFKK2002a, 21 Nov. 2003.
- International organization for standardization. ISO/DIS 13528 statistical methods for use in proficiency testing by interlaboratory compari-sons, 18 Feb. 2002.
- Pedersen MM. Stability of NFKK reference sera X, CAL and reference individual samples. Sum-mary of a draft protocol. Denmark: DEKS; 2003. (In Danish).
- International organization for standardization. EN ISO 17511:2003, In vitro diagnostic medical devices: measurement of quantities in biological samples: metrological traceability of values assigned to calibrators and control materials. ISO, Geneva.
- BIPM, IEC, IFCC, ISO, IUPAC, IUPAP, OIML. Guide to the expression of uncertainty in measure-ment. ISBN 92-67-10188-9, ISO, Geneva, 1995.
- International organization for standardization. EN/ISO 15195:2003, Laboratory medicine: requirements for reference measurement labora-tories. ISO, Geneva.
- Clinical chemistry methods guide 2001–2002. Labquality, Finland, www.labquality.fi
- Snedecor, Cochran. Statistical methods. 8th ed., Iowa State University Press; 1989. pp. 278–80.