Development, Validation and Application of a Fast Sequential Method for Na, K, Ca and Mg Determination in Hemodialysis Solutions by HR-CS F AAS

Hemodialysis solutions are liquid concentrates used during hemodialysis sessions. They are commonly used as a renal replacement therapy. This study aimed to develop a method to determine Na, K, Ca and Mg in hemodialysis solutions by high-resolution continuum source flame atomic absorption spectrometry (HR-CS F AAS) using Design of Experiments (DOE). The combination of the Doehlert Matrix with the desirability function was used to establish a compromise condition in the optimization of the significant variables studied: 60 L/h for acetylene flow rate, 8 mm for burner height, 0.25% (w/v) and 0.60% (w/v) for Cs and La concentrations. The method was validated by following the International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH) guidelines and parameters such as the selectivity, linearity, precision, accuracy and robustness were evaluated. Calibration curves with the ranges of 25-130 mg/L for Na, 1.0-5.0 mg/L for K and Ca, and 0.30-0.70 mg/L for Mg were employed. The method proved to be precise (RSD lower than 2.7%) and accurate (mean recovery data, contemplating the three levels added were: 103.0% for Na, 100.5% for K, 101.3% for Ca and 101.5% for Mg). The developed method enables the sequential multielement determination of Na, K, Ca and Mg in a single run. Requiring only one dilution step, this method significantly reduces analysis time for both sample and standard solutions preparation and measurement. This study presents the first method reported in the literature for multielement determination in hemodialysis solutions, offering an alternative approach to the current European Pharmacopeia method.