Magnesium ion-selective electrode: optimization and flow injection analysis application

The development of manual and Flow Injection Analysis (FIA) methods for the determination of magnesium in aqueous samples by means of a magnesium ion-selective electrode (ISE) is described. A sample pre-treatment solution containing pH buffering compounds and alkaline earth metal complexing agents was developed to minimize interferences and optimize the limits of detection. For the achievement of the desired potential stability of the electrode in the FIA mode, a pulseless syringe pump was employed to eliminate the possibility of a variable streaming potential. This, in conjunction with a laminar flow cell with low and well-controlled dead volume allowed for the simple, semi-automatic, direct, inexpensive, and accurate determination of magnesium in water samples. Results from both the manual and FIA method were corroborated by capillary electrophoresis (CE) and Atomic Absorption Spectroscopy (AAS).