Identification and analysis of calcium speciation in red blood cells by ultrasonic-dialysis capillary electrophoresis inductively coupled plasma optical emission spectrometry

Abstract

Ultrasonic dialysis and capillary electrophoresis inductively coupled plasma optical emission spectrometry were developed for the identification and determination of calcium species in human red blood cells (HRBC). Separation was optimized at 20 kV with a 40 mmol L−1 pH 7.40 Tris-HCl buffer. The free Ca2+ concentration in HRBC cytoplasm was found to be 112 nmol L−1. The recovery for Ca2+ spiked cytoplasm samples ranged from 96.0–103%. Eight primary calcium-containing species (concentrations 1.21–21.8 mg L−1) were found in HRBC. One species had a molecular weight 100 kDa. The calcium species with the greatest mobility was not free Ca2+, but a calcium-erythrocyte membrane species of 50–100 kDa. This method is sensitive and more selective than other common methods for free Ca2+ determination in HRBC.