Quantification of tungsten in real samples spectrophotometrically using optical sensor

Abstract

• The optode was fabricated to detect W(VI) ion at the optimum conditions. • The optode changes color due to W(VI) uptake in buffer of pH 4.25. • The detection limit was found to be 4.45 ng mL −1 of W(VI) • Beer’s law was obeyed in the range of 15–350 ng mL −1 for W(VI) • The method was applied to determine W(VI) in real specimens. A new methodology was devised to detect tungsten in aqueous samples, employing a sensor membrane crafted by physically incorporating a tungsten-selective compound, 5-(2 -bromophenylazo)-6-hydroxypyrimidine-2,4-dione (BPAHPD), into a plasticized poly(vinyl chloride). The addition of Triton X-114 was observed to be advantageous in augmenting the absorption of HWO 4 − ions from the liquid phase into the membrane phase, thereby amplifying sensor absorption intensity. The method established a linear dynamic span of 15–350 ng mL −1 for W(VI), exhibiting a notable correlation coefficient of 0.9992. Quantification and detection limits were determined to be 14.85 and 4.45 ng mL −1 , correspondingly, under optimized conditions. The Sandell responsiveness and molar absorptivity were calculated at 0.0455 ng cm −2 and 4.04 × 10 8 L/mol cm −1 , respectively. The sensor demonstrated superb selectivity, as demonstrated by the negligible influence of potential interfering species. Statistical analyses, encompassing variance ratio F-tests and Student’s t-tests, indicated no substantial differences. The efficacy of the methodology was authenticated through the scrutiny of genuine samples, with statistical comparison to the ICP-AES method.