Quantitation of manganese by use of an electron spin resonance method

An electron spin resonance (ESR) measurement is described for the quantitation of manganese in biological materials. The content of Mn was measured at room temperature by using 5 microL of a solution of the tissue wet-ashed with HNO3. In the ESR spectrum, Mn(H2O)6(2+) showed the characteristic six lines, and interferences were not detected from other substances in the tissues. For these tissue samples, good agreement was obtained between the values obtained by the present method and those obtained by conventional flame atomic absorption spectroscopy. The concentrations of Mn in urine, blood, and most tissues were so low that enrichment of Mn by coprecipitation with ZnS was applied for these samples. It took, however, only 5 min to quantify Mn in 1 mL of urine.