Determination of Strontium Ion in Depilatory Powder, Toothpaste, and Raticide Samples using a Novel and Highly Sensitive Potentiometric Sensor Coupled with a Central Composite Design

The strontium ion, in water-soluble forms, is one of the major pollutant in drinking water. Therefore, a simple, rapid, selective, and sensitive potentiometric carbon paste electrode was developed to measure strontium ion in real samples with complex matrices. To prepare the potentiometric sensor, a synthetic ligand ((E)-4-(((2-amino-4-chlorophenyl)imino)methyl)-5-(hydroxymethyl)-2-methyl pyridine-3-ol) as an efficient ionophore and an ionic liquid (1-Butyl-3-methylimidazolium hexafluorophosphate) as a suitable binder were dispersed in a mixture of graphite powder and graphene oxide. The composition of the sensor was optimized using a central composite design (full factorial) to reduce the number of experimental runs and investigate interactions between effective factors. The proposed sensor showed a Nernstian behavior in the linear concentration range of 1x10-8 to 1.0x10(-1) M with a low detection limit (1.59x10(-9) M) and suitable relative standard division (1.01 %). The proposed sensor can be well applied in the pH range of 3.00-9.50 for the analyte determination. Moreover, the proposed electrode as an indicator electrode was successfully used to measure the Sr(II) concentration in the depilatory powder, toothpaste, and raticide samples.