Plasma sodium and potassium measurement: minimising ISE-flame differences using specimens from patients

Comparison of three methods for oxidative stress-induced potassium efflux measurement

The aim of the study was to compare the potassium efflux measurements (flame photometry (FP), specific electrode (SE) and atomic absorption photometry (AAP)) using a model of erythrocytes exposed to an oxidative stress in various conditions of osmolarity. Human erythrocytes were incubated in 3 different values of osmolarity and in the presence of 50mM AAPH, potassium efflux was measured by FP, SE and AAP at t=0 and every 30min for 2h. These methods were similar for the measurement of global potassium efflux. However, SE detected important amounts of potassium at the beginning of the experiment or in absence of AAPH in comparison with AAP and FP. It is noteworthy that these different methods of measurements were not altered by the osmolarity. FP and AAP make it possible to study the potassium efflux during oxidative stress while SE should be used only for global measurements.

Determination of inorganic ions of clinical interest: state-of-the-art and trends

An overview is presented of techniques, analysers and methods currently available for the determination of inorganic ions of interest in clinical laboratories; methods include those based on activation and inhibition of enzymatic reactions by these target analytes. The foreseeable, trends in this area are also discussed.