Sensitive and selective liquid-liquid extractive spectrophotometric determination of Bismuth(III) from water, pharmaceuticals and synthetic mixtures

In the present research, a cost effective, selective and sensitive extractive spectrophotometric procedure has been developed for the determination of bismuth(III). The method was based upon the complexation reaction of Bi(III) with the sulphur containing reagent, 4-(4′-chlorobenzylideneimino)-3-methyl-5-mercapto-1, 2, 4-triazole in dichloromethane to form orange colored complex at room temperature from hydrochloric acid-potassium chloride buffer having pH 2.0 in presence of potassium iodide. The 1:1:1 orange colored ternary [Bi(III)-CBIMMT-iodide] complex has λmax 409 and 490 nm and stable for more than 72 h. The extracted complex have molar absorptivity 8.860 × 103 L mol-1 cm-1 and 6.875 × 103 L mol-1cm-1 while Sandell's sensitivity is 0.02358 μg cm-2 and 0.03039 μg cm-2 at 409 nm and 490 nm respectively. The system adheres to Beer's law from 4.0 to 21.5 and 5.3–22.5 μg mL-1 at 409 nm and 490 nm respectively; however Ringbom's plot suggests optimum concentration range as 5.25–14.5 and 5.30–12.5 μg mL-1 at 409 and 490 nm respectively. The values of limit of detection and limit of quantification of the method are 0.26 and 0.79 μg mL-1 respectively. The enrichment factor of the method is 2.499 and the method has been applied for analysis of environmental and real samples and separation of Bi(III) from related metals ions. [Display omitted] •Sulphur containing reagent, CBIMMT shows outstanding sensing behavior towards bismuth(III) in buffer medium.•Extraction of bismuth(III) has been carried out without any addition of synergent or modifier at room temperature.•The method does not require surfactant and heating of aqueous phase to develop the colour of the complex.•No need of any sophisticated instrumentation and tedious procedure.•The method is proved to be reliable for analysis of various samples such as water, pharmaceuticals, alloys and permits separation and quantification of bismuth(III) from associated metal ions.