Determination of ionized magnesium in erythrocytes using a potentiometric analyzer

A simple method for the determination of ionized magnesium in erythrocytes using a potentiometric analyzer Microlyte 6 (Kone, Finland) was investigate d. A set of aqueous solutions containing electrolytes at the same concentra tion as in erythrocytes in Tris/TES buffer (pH 7.2) was used as standards. The erythrocyte cell membranes were destroyed using three different methods : (A) HCl solution of pH 3.5, (B) dry ice-acetone mixture, (C) ultrasound. The result did not differ significantly between methods B and C (Student's test, alpha = 0.01). The results were compared with those obtained using th e P-31 nuclear magnetic resonance method (P-31 NMR). The dissociation const ant of MgATP was calculated from the P-31 NMR results. The results obtained from potentiometry and P-31 NMR did not differ significantly (Student's te st, alpha = 0.01). Total magnesium concentration was determined using atomi c absorption spectrometry (AAS). (C) 2001 Elsevier Science B.V. All rights reserved.