LAUSR

Abstract Biological fluids monitoring is one of the important tools in prevention of diseases. Mineral elements in these media are essential factors to collaborate biological monitoring, disease conditions of humans, and maintenance of good health. These minerals are usually measured in laboratories using complicated and expensive techniques as ion chromatography (IC), atomic absorption spectroscopy (AAS), and inductive coupled plasma (ICP). The current work tries to validate alternative simpler and cheaper methods for the measurement of calcium (Ca 2 + ) and magnesium (Mg 2 + ) in the biological medium. Therefore, we had optimized EDTA titration, flame-atomic emission spectroscopy (FAES), and ion-selective electrode (ISE) to measure biological calcium. In addition, EDTA titration and ISE used to measure magnesium in biological samples. In fact, we are the first who totally validated cheapest analytical methods for the analyses of these cations in biological fluids. The influence of standard calibration curve on method imprecision and inaccuracy was examined using external and internal quality control materials. In general, the recoveries of the optimized methods were sufficiently good [92–103%]. Good stable reproducibility was registered especially with the lowest values of the relative standard deviation (RSD) of the ISE. Besides, good readabilities expressed as the limits of quantitation (LOQs) for Ca 2 + measurements using FAES, ISE, and EDTA were (2.1–3.0 mg/L), (3.1–6.1 mg/L), and (3.9–7.7 mg/L), respectively. In addition, the LOQs for Mg 2 + measurements using ISE and EDTA were (1.2–4.5 mg/L) and (2.0–5.7 mg/L), respectively. Difference (%) of the reproducibility of the measurements in 5 days and the uncertainty was in the following range: FAES (just for Ca 2 + ) ISE EDTA. The validated methods showed acceptable correlations (0.9734–0.9990). They provided rapid, less tedious, practical and more accurate alternatives for the quantification of those bivalent cations in human fluids. Consequently, this research supports the implementation of cheap techniques and provides accurate analytical methods for the measurements of biological calcium and magnesium.