Spectrophotometric estimation of hydrazine in various water samples via direct and indirect methods

Direct and indirect spectrophotometric methods were suggested to estimate hydrazine sulphate in various water samples, the first method was based on charge transfer reaction between hydrazine sulphate and alizarin at pH 4.31 to form a very stable red colored complex measured at the selected wavelength 512 nm. The linearity of this method was followed Beer's law at the range of concentration from (0.2-26) mu g, molar absorptivity was (1.17 x 10(4)) l.mol(-1).cm(-1), and Sandal sensitivity was (0.0111)mu g(-2).cm(-1). The second method was based on the oxidation reduction reaction between hydrazine sulphate and chromate then the subsequent reaction of chromate IIII produced with chromazurol S, in acidic medium of 1 N hydrochloric acid (pH 2.0), to produce a burgundy red colored complex measured at 573 nm. Beer's law was obeyed at the range of concentration from (0.4-50)mu g, molar absorptivity was (0.29 x 10(4))l.mol(-1).cm(-1), and Sandal sensitivity was (0.0448) mu g(-2).cm(-1). The limits of detection (LOD) and limits of quantification (LOQ) for the first method were 0.1976 and 0.6584 mu g ml(-)(1) While 0.3257 and 1.0663 mu g ml(-1) for the second method. These two methods were applied for estimation of hydrazine sulphate in various water samples with good recoveries. (C) 2021 Elsevier Ltd. All rights reserved.