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Abstract

This work was influenced by the separation and preconcentration steps carried out to determine metformin (MET) in pharmaceutical preparations and human serum samples. Complex formation method and cloud-point extraction (CPE) coupling with UV-Visible spectrophotometry were used to investigate the study target. The results showed the best optical characteristics for calibration curve and statistical data which were obtained under optimum conditions. The first method is based on the reaction of MET with nickel (II) in an alkaline medium with an absorption maximum (λmax) at 434 nm. Beer's law is obeyed in the concentration range (10-100 μg/ml) with molar absorptivity of 3.9 x 10^3 L/mol·cm. The limit of detection and quantitation values were 2.37 and 7.11 μg/ml respectively. The second method is based on extraction of trace amounts of MET using cloud-point extraction (CPE). This method involves using a nonionic surfactant (Triton X-114) as an extraction medium, which entraps the hydrophobic complex formed between MET and nickel (II) in basic medium as a reaction system for designing the CPE procedure. The optimum conditions were similar to the first method except for the amount of surfactant, which was 0.5 ml. The concentration range for the calibration curve was from 3.5 to 100 μg/ml with molar absorptivity of 1.2 x 10^4 L/mol·cm. This method achieved lower concentrations in the limit of detection and quantitation, which were 0.74 and 2.22 μg/ml respectively. The precision (RSD %) and accuracy (recovery %) of both methods ranged between 0.24-0.47 and 97.86-98.68 respectively. The data from both methods showed high acceptability with the standards of the British Pharmacopoeia through the use of statistical methods (f-test and t-test), indicating that they may be used in the analysis of MET.

Keywords

UV-Vis spectrophotometry, new chelating agent, nickel (II), Cloud point extraction (CPE), Triton x-114

Article Type

Supplemental Issue

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