Kattermann, Kupke und Borner: Enzymatische Bestimmung des Gesamt-Cholesterins 347

tersuchungen zum Problem der Referenzbeieiche wird abschließend eingegangen. Candidate Selected Method for the enzymatic determination of total cholesterol in serum Summary: An enzymatic method is described for the determination of total cholesterol in serum using a single aqueous reagent which can easily be prepared from commertial Substrates and enzymes. The determination is carried out manually, the resulting stable chromogen is measured at a wavelength of 500—550 nm. The cholesterol concentration may be calculated either using a primary cholesterol Standard or a constant factor for a given wavelength. Thie reliability of the method is reported: Data for the imprecision are given on the basis of a survey in 3 laboratories, the accuracy is established by comparison with a definitive and a reference method. Analytical and biological interferences are briefly discussed and results with this enzymatic method are reported concerning the reference values for serum cholesterol. Einführun