Synthesis of New Reagent 2,6‐Diacetylpyridine Bis‐4‐Phenyl‐3‐Thiosemicarbazone (2,6‐DAPBPTSC): Selective,Sensitive and Extractive Spectrophotometric Determination of Co(II) in Vegetable,Soil, Pharmaceutical and Alloy Samples

New synthesized reagent 2,6‐diacetylpyridine bis‐4‐phenyl‐3‐thiosemicarbazone (2,6‐DAPBPTSC) is proposed as a sensitive and selective analytical reagent for the extractive spectrophotometric determination of cobalt(II). Cobalt(II) forms a reddish brown colored complex with 2,6‐DAPBPTSC, which is extracted into isoamylalcohol, under optimum conditions. The maximum absorption of the isoamylalcohol extract is measured at 400 nm. Beer's law is applied in the range 0.6‐6.0 ppm of cobalt(II). The molar absorptivity and Sandell's sensitivity of the complex is calculated as 2.2 × 10⁴ L mol^?1 cm^?1 and 2.68 × 10^?3 μg cm^?2, respectively. An adequate linearity with a correlation coefficient value of 0.969 is obtained for the Co(II)‐2,6‐DAPBPTSC complex. The instability constant of the complex, calculated from Asmus' method is 3.75 × 10^?4 The precision and accuracy of the method is checked with calculation of relative standard deviation (n = 5), 0.388 and the detection limit a value is 0.0028 μg mL^?1. The method is successfully employed for the determination of cobalt(II) in real samples, such as vegetables, soil, water samples, standard alloy samples, and the performance of the present method was evaluated in terms of Student ‘t’ test and Variance ‘f’ test, which indicates the significance of the present method is an inter comparison of the experimental values, using atomic absorption spectrometer (AAS).