External quality assurance scheme EQA

Any laboratory that undertakes diagnostic work should be a member of an appropriate EQA scheme. No one can be an expert in all aspects of such a diverse field. EQA scheme results can highlight areas of weakness that need addressing. Comparing results with a wide range of other laboratories can also provide reassurance and confidence that standards are good. 

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Seth J, Hanning I, Al-Sadie R, Bacon RRA, Hunter WM. The UK external quality assurance scheme (EQAS) for FSH, LH and prolactin— the past decade. Clin Chem 1990 36 1003. 

Experience has shown that these assays can perform exceeding well but only if the user belongs to an external quality assurance scheme (EQAS) which monitors performance and uses target values determined by GC-MS (e.g., 170). Table 8 illustrates some GC-MS methods which have been published in the last 20 years, not all of which are suitable for use as reference methods. 

External quality assurance scheme (EQA) 407 Acknowledgements 407 Suggested Further Reading 407 References 408... 

The highest sensitivity and selectivity in vitamin E LC assays are obtained by using fluorescence or electrochemical detection. In the former, excitation at the low wavelength (205 nm) leads to improved detection limits but at the expense of selectivity, compared with the use of 295 nm. Electrochemical detection in the oxidation mode (amperometry or coulometry) is another factor 20 times more sensitive. In routine practice, however, most vitamin E assays employ the less sensitive absorbance detection at 292-295 nm (variable wavelength instrument) or 280 nm (fixed wavelength detectors). If retinol and carotenoids are included, a programmable multichannel detector, preferably a diode array instrument, is needed. As noted previously, combined LC assays for vitamins A, E, and carotenoids are now in common use for clinical chemistry and can measure about a dozen components within a 10 min run. The NIST and UK EQAS external quality assurance schemes permit interlaboratory comparisons of performance for these assays. 

Table 1.2.1 Examples of quantitative external quality assurance (EQA) schemes available in Europe in biochemical genetics...

A Proficiency Test (PT) is defined as the study of laboratory performance by means of ongoing interlaboratory test comparisons . It is also known as an external quality assessment scheme, external laboratory performance check or external quality assurance (EQA). There are many such schemes run by independent external bodies for different analytes in a variety of matrices. Evidence in published papers shows that the performance of analytical laboratories improves as a result of participating in Proficiency Testing schemes and the betw een-laboratory precision can improve, sometimes dramatically. This is especially true in the early years of participation. 

External Quality Assurance (EQA) schemes attempt to provide an independent assessment of a laboratory s performance usually with respect to a defined assay. Such schemes complement (and use) ICQ. The basis of the schemes is... 

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