In clinical chemistry

Wang, J. Electroanalytical Techniques in Clinical Chemistry and Eaboratory Medicine. VCH New York, 1998. 

Immunoassays. Immunoassays (qv) maybe simply defined as analytical techniques that use antibodies or antibody-related reagents for selective deterrnination of sample components (94). These make up some of the most powerflil and widespread techniques used in clinical chemistry. The main advantages of immunoassays are high selectivity, low limits of detection, and adaptibiUty for use in detecting most compounds of clinical interest. Because of their high selectivity, immunoassays can often be used even for complex samples such as urine or blood, with Httle or no sample preparation. 

Fluorescence. The fluorescence detection technique is often used in clinical chemistry analyzers for analyte concentrations that are too low for the simpler absorbance method to be appHed. Fluorescence measurements can be categorized into steady-state and dynamic techniques. Included in the former are the conventional simultaneous excitation-emission method and fluorescence polarization. 

Ion Selective Electrodes Technique. Ion selective (ISE) methods, based on a direct potentiometric technique (7) (see Electroanalytical techniques), are routinely used in clinical chemistry to measure pH, sodium, potassium, carbon dioxide, calcium, lithium, and chloride levels in biological fluids. 

J. Wang, Electroanalytical Techniques in Clinical Chemistry andEaboratoy Medicine, VCH, New York, 1988. 

The method can also be adapted to determine the amount of a substance in solution by adding a catalyst which will destroy it completely, and measuring the concomitant change in for example, the absorbance of the solution for visible or ultraviolet radiation. Such procedures are applied in clinical chemistry. 

Supported in part by a NIH Research Training Grant in Clinical Chemistry 5 TOl Q102122-02. 

Natelson, S. Techniques in Clinical Chemistry, 3rd Edition Chas C Thomas, Springfield, 111, 1971 ... 

Bowers, 6. N., Jr. Kelley, M. L. and McComb, R. B. Precision estimates in clinical chemistry. I. Variability of analytic results in a survey reference sample related to the use of a non-human serum alkaline phosphatase. Clin. Chem. (1967), 14, 595-607. 

General Description. Liquid chromatography encompasses any chromatographic method in which the mobile phase is a liquid (c.f. gas chromatography). A variety of stationary phases and retention mechanisms are available such that a broad range of modes of separation are possible. It is worthwhile to briefly describe the important modes that find use in clinical chemistry. 

Sch artZ9 M.K. "Interferences In Diagnostic Biochemical Procedures". Advances In Clinical Chemistry> pp. 1-45,... 

The remarkable selectivity that is inherent in the reaction of an antibody with the antigen or hapten against which it was raised is the basis for the extensive use of immunoassay for the rapid analysis of samples in clinical chemistry. Immunochemical reactions offer a means by which the applicability of potentiometric techniques can be broadened. A number of strategies for incorporating immunoassay into the methodology of potentiometry have been explored... 

Meyerhoff, M. E., Opdycke, W. N. Ion-Selective Electrodes, in Advances in Clinical Chemistry 25, 1-47 New York, Academic Press 1986... 

The basic aim of PEC applications in clinical chemistry, apart from the recovery of standards of endogenous substances, consists of structural identification of isolated (without further separation) substances of relatively high purity. Therefore, the majority of works devoted to this topic pertain to semipreparative separation. Obtaining low amounts of analytes, achieved by coupling TEC with modem... 

Papadoyannis, N. and Samanidou, V.A., Sample pretreatment in clinical chemistry, in Separation Techniques in Clinical Chemistry, Aboul-Enein, H.Y., Ed., Marcel Dekker, New York, 2001, chap. 1. 

Jain, R., Thin-layer chromatography in clinical chemistry, in Practical Thin-Layer Chromatography A Multidisciplinary Approach, Eried, B. and Sherma, J., Eds., CRC Press, Boca Raton, PE, 1996, chap. 7. 

Figure 33.1 is typical of many situations in clinical chemistry it shows a tight normal group (the EU group) and spreading out from it much more disperse... 

Whitehead TP (1976) Quality Control in Clinical Chemistry. Wiley, Chichester,... 

The list of elements and their species listed above is not exhaustive. It is limited to the relatively simple compounds that have been determined by an important number of laboratories specializing in speciation analysis. Considering the economic importance of the results, time has come to invest in adequate CRMs. There is a steadily increasing interest in trace element species in food and in the gastrointestinal tract where the chemical form is the determinant factor for their bioavailability (Crews 1998). In clinical chemistry the relevance of trace elements will only be fully elucidated when the species and transformation of species in the living system have been measured (ComeUs 1996 Cornelis et al. 1998). Ultimately there will be a need for adequate RMs certified for the trace element species bound to large molecules, such as proteins. 

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. 

SlEKMANN L (1979) Determination of steroid hormones by the use of isotope dilution mass spectrometry a definitive method in clinical chemistry. J Steroid Biochem 11 117-123. 

Westgard jo, Barry PL, Hunt MR (1981) A multi-rule Shewhart chart for quality control in clinical chemistry. Clin Chem 27 493-501. 

Reference materials have been long used in clinical chemistry the first biological reference material was developed by Paul Ehrlich in 1897 (Btittner 1995). The routine use of RMs in clinical chemistry started in the early 1970 s and was driven by... 

A second reason for using reference materials in clinical chemistry is to ensure values obtained are traceable to those in a recognized, authoritative reference material (Johnson et al. 1996). As a result, the assignment of values of secondary and tertiary reference materials, calibrants, controls, and proficiency samples shordd be performed as precisely as possible (Johnson et al. 1996). Surprisingly there is still debate on this topic, and on the need for clinical chemistry to incorporate the principals of analytical quality assurance (Dybkaer et al. 1999). 

In clinical chemistry, a great number of components are to be determined. These components may be classified according to their physiological fimction. In occupational toxicology, a division into functional chemical components may be a better classification. 

Many pesticides are neurotoxicants poisoning the nervous system. A number of pesticides are acetyl cholinesterase inhibitors (Serat and Mengle 1973). Generally, pesticides determination has been performed by GC since the 1960 s (Morrison and Durham 1971 Fournier et al. 1978). There are no reference materials for pesticides in urine or serum, although as with PAHs there are a number biological matrices certified for the content of various pesticides available for environmental food and agriculture analysis and which may have some application in clinical chemistry. 

Enzymes are mostly determined by some spectrophotometric methods in clinical chemistry laboratories, but immunochemical and molecular biological techniques are finding their way into routine laboratory procedures. 

Gelomacher-von Mallinckrodt M, Meissner D 1994) General aspects of the role of metals in clinical chemistry. In Seiler HG, Sigel A, Sigel H, eds. Handbook on metals in dinical and analytical chemistry. Dekker, New York. 

Analytical studies in clinical chemistry relating to the determination of methylxanthines are concentrated in two areas. The first of these involves the analysis of various ethical pharmaceuticals. The second area involves the analysis of various body fluids for methylxanthines and their metabolites. 

---