Development of a reliable analytical method for the precise extractive spectrophotometric determination of osmium(VIII) with 2-nitrobenzaldehydethiocarbohydrazone: Analysis of alloys and real sample

• An effective new chromogenic thio ligand was synthesized and applied for spectrophotometric determination of osmium(VIII).
• The method is fast, accurate and reliable analytical method for quantitative spectrophotometric determination of osmium(VIII).
• The developed method free from large number of cations and anions.
• The method was efficiently applied to analysis of synthetic mixtures of alloys and minerals, which is confirmed by AAS.

The proposed method demonstrates that the osmium(VIII) forms complex with 2-NBATCH from 0.8 mol L− 1 HCl at room temperature. The complex formed was extracted in 10 mL of chloroform with a 5 min equilibration time. The absorbance of the red colored complex was measured at 440 nm against the reagent blank. The Beer's law was obeyed in the range of 5–25 μg mL− 1, the optimum concentration range was 10–20 μg mL− 1 of osmium(VIII) as evaluated by Ringbom's plot. Molar absorptivity and Sandell's sensitivity of osmium(VIII)-2NBATCH complex in chloroform is 8.94 × 103 L mol− 1 cm− 1 and 0.021 μg cm− 2, respectively. The composition of osmium(VIII)-2NBATCH complex was 1:2 investigated from Job's method of continuous variation, Mole ratio method and slope ratio method. The interference of diverse ions was studied and masking agents were used wherever necessary. The present method was successfully applied for determination of osmium(VIII) from binary, ternary and synthetic mixtures corresponding to alloys and real samples. The validity of the method was confirmed by finding the relative standard deviation for five determinations which was 0.29%.

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