A sparingly soluble salt of a heteropoly acid is used for the determination of an analyte which is an aromatic amine rich in electrons or together with another substance leads to such an amine. The analyte is determined by means of the heteropoly blue color formed....http://www.google.de/patents/US5521060?utm_source=gb-gplus-sharePatent US5521060 - Use of a sparingly soluable salt of a heteropoly acid for the determination of an analyte, a corresponding method of determination as a suitable agent therefor
