SPECTROPHOTOMETRIC DETERMINATION OF ARSENIC, LEAD IN ENVIRONMENTAL AND BIOLOGICAL SAMPLES USING 2, 5­THIOPHENE DICARBOXALDEHYDE, THIOSEMICARBAZONE

Abstract

Analytical application of 2,5‐thiophene dicarboxaldehyde, thiosemicarbazone(TDATSC) is described for the direct non‐extractive
spectrophotometric determination of AsIII, and PbII in aqueous environmental and biological samples .The reagents react with arsenic, in acidic
medium (pH 6.0., sodium acetate‐acetic acid buffer) to form light yellow colored, 2:1 (M: L) complexes. The reagents react with lead in basic
medium (pH 9.0. buffer) to form light blue colored, 2:1 (M: L) complexes. The colour reactions are instantaneous and absorbance values remain
constant for over 24 h. The molar absorptivity and Sandell’s sensitivity of TDATSC methods are found to be 1.45 X 10 4 L mol‐1 cm‐1 and 0.0014 µg
cm‐2 of AsIII, of. 1.89 X 10 4 L mol‐1 cm‐1 and 0.0019 µg cm‐2 of PbII respectively. The systems obey Beer’s law in the range of 0.123‐2.537 µg/ml of AsIII,
2.0− 2.4 µg/ml of PbII .Since TDATSC method is more sensitive it was applied for the determination of Arsenic, lead in environmental and biological
samples