[Determination of inorganic phosphorus on the (Cobas) Bio (direct method without deproteinization) (author's transl)].

The direct molybdate method for the determination of inorganic phosphorus was adapted to the (Cobas) Bio centrifugal analyzer. We evaluated test characteristics such as reaction time, linearity range, accuracy and precision within series and from day to day. Accuracy was checked using control sera, three different types of recovery experiments, and by experiments running in parallel. Because the results of the determination of inorganic phosphorus depend greatly on the method and the procedure used (with/without deproteinization), we checked the accuracy not only by experiments running in parallel, but by comparison with the following methods: the malachite green method without and with two different techniques for deproteinization, the molybdate/p-methylaminophenol sulfate method with and without deproteinization, and the molybdate/vanadate method with deproteinization. Using patients' sera as well as control sera, it was shown that the preferred molybdate method gave, within the normal range of errors, the same results as the malachite green method without deproteinization.