A rapid microtechnique for the preparation of biological material for the simultaneous analysis of calcium, magnesium and protein

No simple documented method of sample preparation is available for the analysis of calcium and magnesium in biological samples despite increasing awareness of the biological roles of these cations. The technique described here is rapid, avoids the use of dangerous reagents or costly equipment, and allows accurate determination of protein, calcium, and magnesium content of the speciment after sample preparation. Tissue is solubilized in 1 n NaOH after which one aliquot is used for protein analysis by the method of Lowry et al. (1951) (J. Biol. Chem.193, 265–275), and another is used for determination of cations by atomic absorption spectroscopy. The method was used to analyze biological samples including adipocyte subcellular fractions, bovine liver, and orchard leaves. Results correlated well with those using reference wet ashing and low-temperature ashing techniques with correlation coefficients (r2) of 0.95 for calcium and 0.997 for magnesium. Intraassay coefficients of variation were 4–4.2%. The base-digestion technique is a simple, rapid, and precise method which avoids most of the limitations of currently available sample preparation techniques.