Determination of Lithium (I) in Pharmaceutical Products and Biological Samples by a Simple Potentiometric Sensor Based on a Recently Synthesized Chromene Derivative as the Ionophore

In this research, a coated graphite polyvinyl chloride (PVC) membrane electrode was fabricated for the potentiometric determination of lithium based on 13-(3-nitrophenyl)-12H,14H-benzo[g]chromeno[2,3-b]chromene-7,12,14(13H)-trione (L) as the ionophore. The best Nernstian response was observed from the membrane composition of 31% PVC, 7% L, 2% NaTPB, and 60% dioctyl phthalate (DOP) as the plasticizer. The designed sensor showed a wide linearity over the concentration range of 1×10-8-1×10-3 mol L-1 with the slope of 60.2±0.3 mV decade-1, and the limit of detection (LOD) of 7.5×10-9 mol L-1. The selectivity of the designed sensor was investigated by matched potential method and no serious interference was observed. The response time and life span of the electrode were 5s and 16 weeks, respectively. The potential response of the electrode was independent of solution pH in the pH range of 3.0-12.0. The influence of the presence of organic solvents on the potential response of the electrode was also scrutinized, and the results showed that the designed sensor keeps its Nernstian behavior in solutions with 20% non-aqueous content. At the end, the electrode was successfully applied to determine lithium carbonate in tablet, urine and serum samples with the recovery% values of 96.0 to 106.33 and RSD% 1.99-4.45.