Optical quantification of sodium potassium and calcium ions in diluted human plasma based on ion-selective liquid membranes

摘要

Abstract: With the presented ion-selective optode membranes total ion concentrations of sodium, potassium, and calcium are measured reversibly with the same selectivity as in potentiometric systems. The optically sensing membranes combine the well established neutral carriers together with neutral so-called chromoionophores which change their absorption spectra in the VIS region upon complexation of hydrogen ions in the same membrane phase. Membranes are mounted in an optical flow-through cell with a volume of 300 $mu@l. All measurements are referred to a pair of blank-membranes in a reference cell to compensate for interferences induced by the sample. The response time is in the range of seconds. A good correlation to reference methods is achieved.!28