A simple spectrophotometric method for the determination of trace levels of molybdenum using n,n '-bis(2-hydroxy-5-bromo-benzyl)1,2 diaminopropane
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The present work describes a selective, rapid and economical spectrophotometric method for the determination of molybdenum using N,N'-bis(2-hydroxy-5-bromo-benzyl)1,2 diaminopropane. Molybdenum(VI) reacts with N,N'-bis(2-hydroxy-5-bromo-benzyl)1,2 diaminopropane to form a stable 1:1 yellow complex with an absorption maximum at 342 nm. The reaction is completed within 10 min and the absorbance of the molybdenum complex remains stable for at least 1 week at room temperature. The effective molar absorption coefficient at 342 nm was 9.6 x 10(3) L mol(-1) cm(-1). Under optimal conditions, the complex obeys Beer's law from 0 to 9.9 mu g mL(-1). The relative standard deviation was 0.08% (for 11 samples, each containing 6 mu g mL(-1) molybdenum). Under the optimum conditions, the detection limit (3 sigma) was 17.7 mu g L-1 for molybdenum without any preconcentration. The precision was determined from 30 results obtained for 4.80 mu g mL(-1) Mo(VI); the mean value of a molybdenum(VI) was 4.83 mu g ml(-1) with a standard derivation of 0.002 mu g ml(-1) molybdenum(VI).