IFCC

In 1978 the International Federation of Clinical Chemistry produced a comprehensive summary of the objectives of External Quality Assessment (IFCC 1978). The first six points of Table 4.1 summarize the IFCC objectives the seventh has developed since that time and is of considerable importance in many countries where strict control over laboratories undertaking particular types of work is required by legislation or by appropriate professional organizations. 

Ingamells CO, PiTARD FF (1986) Applied Geochemical Analysis, pp L-84.Wiley, New York. International Federation of Clinical Chemistry (IFCC) (1978) Expert Panel on Nomenclature and Principles of Quality Control in Clinical Chemistry. Clin Chim Acta 83 L89F-202F. International Organization for Standardization (ISO) (1993) Guide to the expression of uncertainty. Geneva. 

At the end of 1996, a collaboration agreement was signed between the European Commission and the International Federation of Clinical Chemistry (IFCC) for the joint IRMM/IFCC production and certification of clinical reference materials. 

The certification of a cortisol reference serum panel came to an end with the introduction of IRMM/IFCC-45iat the end of 1999. It consists of 34 sera (80-750 nmol/L) and has been certified using ID-GC/MS as a reference method. 

Ongoing projects include the certification of enzyme CRMs for GGT, LD, ALAT, CK-MB, ASAT, ALP and a-amylase at 37°C, according to adapted IFCC methods. 

The first four materials (IRMM/IFCC-452, 453, 454, 455) are expected to be released during 2000. Projects on the certification of reference materials for cardiac marker (myoglobin) and total protein concentration in serum are under discussion. Even so the number of available CRMs for clinical chemistry and occupational toxicology is still limited. This has to do with the complexity of physiological compounds (e.g. proteins), the instabihty (e.g. enzymes), or the volatility (e.g. solvents). 

McQueen MJ, Roberts HR, Siest G (1995) Reference materials and reference measurement systems in laboratory medicine - a major international meeting organized by the International Federation of Clinical Chemistry (IFCC), Geneva, October 5-7, 1994. Europ J Clin Chem Clin Biochem 33 977-999. 

ISO 3534-1 (1993), International Organization for Standardization (BIPM, IEC, IFCC, ISO, IUPAC, IUPAP, OIML), International vocabulary of basic and general terms in metrology. Geneva... 

Notwithstanding that a large number of definitions exist that have been produced and harmonized by many commissions of international organizations (e.g., IUPAC, IUPAP, ISO, BIPM, IEC, IFCC, OIML), there are still official recommendations and definitions which are not completely satisfying and sometimes confusing (Prichard et al. [2001]). 

Accuracy is defined in the name of BIPM, IEC, IFCC, ISO, IUPAC, IUPAP, and OIML as the closeness of agreement between the result of a measurement and the true value of the measurand (ISO 3534-1 [1993] Fleming et al. [1996b]). Accuracy characterizes the absence of a relevant bias of a measured value. As can be seen from Fig. 4.1, accuracy is a measure that combines the effects of both random and systematic deviations. Therefore, a bias can only be detected if it exceeds the range of random error. 

Clinical chemistry, particularly the determination of the biologically relevant electrolytes in physiological fluids, remains the key area of ISEs application [15], as billions of routine measurements with ISEs are performed each year all over the world [16], The concentration ranges for the most important physiological ions detectable in blood fluids with polymeric ISEs are shown in Table 4.1. Sensors for pH and for ionized calcium, potassium and sodium are approved by the International Federation of Clinical Chemistry (IFCC) and implemented into commercially available clinical analyzers [17], Moreover, magnesium, lithium, and chloride ions are also widely detected by corresponding ISEs in blood liquids, urine, hemodialysis solutions, and elsewhere. Sensors for the determination of physiologically relevant polyions (heparin and protamine), dissolved carbon dioxide, phosphates, and other blood analytes, intensively studied over the years, are on their way to replace less reliable and/or awkward analytical procedures for blood analysis (see below). 

The properties of a pH electrode are characterized by parameters like linear response slope, response time, sensitivity, selectivity, reproducibility/accuracy, stability and biocompatibility. Most of these properties are related to each other, and an optimization process of sensor properties often leads to a compromised result. For the development of pH sensors for in-vivo measurements or implantable applications, both reproducibility and biocompatibility are crucial. Recommendations about using ion-selective electrodes for blood electrolyte analysis have been made by the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) [37], IUPAC working party on pH has published IUPAC s recommendations on the definition, standards, and procedures... 

International Federation of Clinical Chemists (IFCC), Centre du Medicament, Universite de Nancy 1, Nancy, France. 

ISO. lEC. BIPM. OIML. lUPAC. lUPAP. IFCC They jointly published the VIM... 

OIML - International Organization of Legal Metrology (www.oiml.org) lUPAP - International Union of Pure and Applied Physies (www.iupap.org) IFCC - International Federation of Clinieal Chemistry (www.ifcc.org/ifcc.asp) VIM - International Vocabulary of Metrology - Basic and General Concepts and associated Terms... 

Guide to the Expression of Uncertainty in Measurement , published 1993 by iSO in coiiaboration with BIPM, lEC, iFCC, iUPAC, lUPAP and OIML. 

A13. Adam., R, Nekola, R, and Chenickova, M., Evaluation of the o -l-nucroglobulin levels in the cerebrospinal fluid. In Proceedings of the Laboratory Medicine 11th IFCC European Congress of Clinical Chemistry, Tampere, Einland, 2—7 July, p. 519, 1995. 

Guide to the expression of uncertainty in measurement (GUM), BIPM/IEC/IFCC/ISO/IUPAC/IUPAP/OIML, corrected and reprinted 1995. 

For the above reasons, the IFCC recommendations on activity coefficients [19] and the measurement of and conventions for reporting sodium and potassium [21] and chlorides [25] by ISEs were developed. At the core of these recommendations is the concept of the adjusted active substance concentration (mmol/L), as well as a traceable way to remove the discrepancy between direct and indirect determinations of these electrolytes in normal sera. Extensive studies of sodium and potassium binding to inorganic ligands and proteins, water binding to proteins, liquid-junction effects and the influence of ionic strength have demonstrated that the bias between sodium and potassium reports obtained from an average ISE-based commercial... 

Methodology and Clinical Applications of Ion-Selective Electrodes, Vols. 1-13, IFCC, Milan, Italy, 1979-1991. 

A. Lewenstam, M. Maj-Zurawska, N. Blomqvist and K.-S. Saarinen. In Methodology and Clinical Application of Blood Gases, pH, Electrolytes and Sensor Technology, Vol. 12. IFCC/WGSE-AACC/EBGD, Monterey, 1990, pp. 269-278. 

ISO (1995) Guide Expression of Uncertainty in Measurement, Leitfaden zur Angabe der Unsicherheit beim Messen (GUM), Joint publication with BIPM, IEC, IFCC,... 

J.M. (1997) A supplement to the approved IFCC recommendation on the theory of reference values. Pure and Applied Chemistry, 69,1601-11. 

Solberg, H.E. (1987) International Federation of Clinical Chemistry (IFCC), Scientific Committee, Clinical Section, Expert Panel on Theory of Reference Values. Approved recommendation (1985) on the theory of reference values. Part 1. The concept of reference values. Journal of Clinical Chemistry and Clinical Biochemistry, 25, 335-42. 

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