DETERMINATION OF CALCIUM AND MAGNESIUM IN CARDIAC AND SKELETAL-MUSCLE BY ATOMIC-ABSORPTION SPECTROSCOPY USING STOICHIOMETRIC NITROUS OXIDE-ACETYLENE FLAME

A highly sensitive technique is reported for the determination of calcium and magnesium contents in demoisturized, defatted and nitric acid digested muscle by atomic absorption spectrometry using stoichiometric nitrous oxide-acetylene flame of 0.2 cm red cone height. Calcium and magnesium standards and muscle specimens were prepared in an aqueous medium containing 51.15 mM potassium chloride and 0.375 M nitric acid for spectral analyses. Extracts of demoisturized and defatted muscle specimens weighing between 10-50 mg were diluted to 1:1O and 1:210 fold for Ca and Mg determinations respectively. Burner head clogging was eliminated by defatting the muscles and discarding the acid undigested muscle residues through centrifugation. Muscle Ca and Mg contents are expressed in MEq/kg of fat free dry muscle and also as Mg/Ca ratio. Under certain circumstances, the Mg/Ca ratio calculation eliminates nonsystematic errors derived from the analytical procedures. The smallest sample size which can be confidently analyzed using this method is ca 0.8 mg of dry defatted muscle which corresponds to approximately 4.0 mg of wet fresh muscle. Recovery study reveals 99.86 ± 0.76% precision for calcium and 99.66 ± 0.86% precision for magnesium determinations from inherent muscle matrix. Fifty to sixty specimens can be analyzed per hour of actual instrument operation. © 1979, Taylor & Francis Group, LLC. All rights reserved.