Direct and First Derivative Spectrophotometric Determination of Manganese (II) in Tap Water, Milk, Alloy Steels and Plant Samples

Abstract

A simple, rapid, sensitive and selective method is developed for the spectrophotometric determination of
manganese (II). The reagent, 2-Hydroxy-3-methoxy benzaldehyde thiosemicarbazone (HMBATSC) gives
greenish brown colored water soluble complex in aqueous DMF medium with manganese (II). The greenish
brown colored Mn (II) – HMBATSC complex shows maximum absorbance at 435 nm in the pH range 9.0 –
10.0. However, at this wavelength, the reagent shows considerable absorbance. At 445 nm, the complex shows
large absorbance while the reagent blank shows negligible absorbance. Hence, the analytical studies are carried
out at 445 nm at pH 9.5. The molar absorptivity and Sandell’s sensitivity are 1.96 x104 l mol-1 cm-1 and 0.028 μg
cm-2 respectively. Beer’s law is obeyed by Mn (II) in the range 0.1373–2.746 μg mL-1
. The composition (M:L)
of the complex has 1:1 and stability constant of the complex is calculated as 1.22 x107
. The effect of various
diverse ions also incorporated. A first order derivative spectrophotometry has also been proposed for the
determination of Mn (II). The present method is applied for the determination of manganese in tap water, milk,
alloy steels and plant samples.