ION CHROMATOGRAPHY AS POTENTIAL REFERENCE METHODOLOGY FOR THE DETERMINATION OF TOTAL SODIUM AND POTASSIUM IN HUMAN SERUM

The potential of ion chromatography to serve as a new reference method principle for the determination of total sodium and potassium in huma n serum was investigated. Sample pretreatment consisted of acidic dilu tion and filtration and detection was based on conductivity. Methods f or the separate and simultaneous determination of both analytes were i nvestigated. Further, the influence of calibration (using either a sin gle-point calibration or a standard curve) on method imprecision, inac curacy and analysis time was examined. The best method performance was achieved by separate analysis using single-point calibration with bra cketing analysis scheme. For this variant, the mean total coefficient of variation for sodium and potassium was 1.0% and the mean method bia s was -0.2% for sodium and +0.2% for potassium, as determined with thr ee control materials from the National Institute of Standards and Tech nology. Our results are comparable to those of reference methods based on flame atomic emission spectrometry. Therefore, we consider ion chr omatography as a valuable reference methodology for the determination of total sodium and potassium in human serum.