Abstract:
A very simple, ultra-sensitive and highly selective non-extractive . spectrophotometric method for the determination of trace amount of molybdenum (VI) using 1,5 - diphenylcarbohydrazide (DPCH) has been developed. 1,5 - diphenylcarbohydrazide (DPCH) reacts in slightly acidic media (0.01 - 0.06M H2SO4) of 50% 1,4 - dioxane with molybdenum(VI) to give a red-violet chelate which has an absorption maximum at 520 nm. The average molar absorption co-efficient and Sandell`s sensitivity were found to be 4.85 x 104 L mol-` cm "` and 15 ng cm-2 of Mov` , respectively. Linear calibration graphs were obtained for 0.1 - 60 pg ML". The stoichiometric composition of the chelate is 1: 3 (Mo : DPCH). The absorbance intensity of the metal chelate reaches at constant value (after heating of 10 mins at 60 ± 5 °C) within 3/4 hour and remain unchanged for over 48 hours. Large excess of over 60 cations, anions and complexing agents (like tartrate, oxalate, chloride, phosphate thio-urea, SCN-` etc.) do not interfere in the Mo determination. The developed method was successfully used in assaying in several standard reference materials (alloys and steels) as well as` in some, environmental waters (inland and surface), biological samples (human blood and urine), soil samples and complex synthetic mixtures. The methods have high precision and accuracy (s = ± 0.01 for 5pg mL"`).
Page(s):
123-132
DOI:
DOI not available
Published:
Journal: Pakistan Journal of Analytical Chemistry, Volume: 4, Issue: 2, Year: 2003