[Comparative studies on the determination of thiocyanate in biological materials (author's transl)].

On verifying methods for the determination of thiocyanate in biological materials, we started from the technique as described by Boxer and Rickards [5]. In different methods, the accuracy of the data obtained is affected by the deproteinization process or interfered with iron (III) ions or pyridine/benzidine, the deproteinization process being the decisive factor. This holds true especially in respect of interfering factors that remain in the supernatant (low-molecular amino compounds) and in respect of the coprecipitation of thiocyanate, the nature of the respective biological material playing an important part in both cases. At higher thiocyanate concentrations, pretreatment with a denaturing agent that is commonly used to deproteinization of human and bovine sera involves a small loss of thiocyanate due to coprecipitation. In case of high demands on reproducibility and accuracy of the analytical results, and in case of special analytical problems, isolation of thiocyanate is absolutely necessary (chromatography on Sephadex, aeration after conversion to hydrogen cyanide). Gas chromatography is suited for determining thiocyanate in whole blood.