Reference methods for total cholesterol and total glycerol.

In internal and external quality assessment of clinical chemical analyses, the use of reference method values is prescribed in the Federal Republic of Germany as a measure of accuracy control. In the field of lipid analyses, reference methods are available for measuring total cholesterol and total glycerol in control sera. The reference measurement procedures are based on the highly accurate analytical principle of isotope dilution mass spectrometry. A very detailed protocol that ensures a high level of reliability must be followed when reference measurement procedures are carried out. The introduction of reference methods as a basis for accuracy control has greatly limited the unacceptable use of inaccurate routine methods.