Spectrophotometric determination of lead in medicinal leaf and environmental samples using 5 - methylthiophene – 2 - carboxaldehyde ethylenediamine ( MTCED )

A simple, rapid and sensitive spectrophotometric method was developed for the determination of Pb (II) using 5methylthiophene–2-carboxaldehyde ethylenediamine (MTCED) as an analytical reagent. The reagent has been synthesized and characterized using IR, H NMR and Mass spectral data. The metal ion in aqueous medium forms light yellow colored complex with MTCED at pH 3.0(sodium acetate-hydrochloric acid buffer solution) showing maximum absorbance at 380 nm. Hence, analytical studies were further carried out at 380nm. The reagent reacts with lead in acidic medium to form light yellow colored 1:1. The color reactions are instantaneous and absorbance values remain constant for 24 hours. The composition of the Pb (II) complex with MTCED was studied by the method of job’s continuous variation and molar ratio method. Beer’s law was obeyed in the range of 0.272.4 μg mlof Pb (II). The molar absorptivity and sandall’s sensitivity of the method were 5.86 x 10 Lmolcm and 0.0017 μg/ cm respectively. Since MTCED method is more sensitive it was applied for the determination of lead in medicinal leaves and environmental samples.