Determination of Mn2+ in Pharmaceutical Supplements by a Novel Coated Graphite Electrode Based on Zolpidem as a Neutral Ion Carrier

Manganese plays a key role in the health of human beings, therefore, its determination is very important in medical fields. In this regard, for the first time, a novel coated graphite electrode was constructed for determination of manganese(II) by using zolpidem as an ionophore. The best performance was obtained for the membrane composition of PVC (32%), potassium tetrakis (4-chlorophenyl) borate (3%) as ionic additive, zolpidem (10%) as ionophore and dioctyl phthalate (55%) as plasticizer. The linear working range of the potentiometric sensor was from 1 × 10-7-1 × 10-2 M. The electrode shows an exquisite Nernstian slope value of 29.7 mV Decade-1 and its limit of detection was 9 × 10-8 M. The potential response of the membrane sensor was also evaluated in non aqueous mediums, and it was found out that the electrode can also be used in systems containing 15% of ethanol and acetone organic solvents. The selectivity was also inspected through matching potential method for 20 different cations, and the electrode demonstrated a significant selectivity toward Mn2+ for all of the studied cations. In the end, the applicability of the electrode in the determination of Mn2+ in dietary supplements, as real samples, was investigated.