A simple spectrophotometric method for the determination of trace levels of molybdenum using N,N′-bis(2-hydroxy-5-bromo-benzyl)1,2 diaminopropane

• A novel spectrophotometric method was developed for determination of molybdenum.
• Mo(VI) reacts with N,N′-bis(2-hydroxy-5-bromo-benzyl)1,2 diaminopropane.
• Detection limit was 17.7 μg L−1 for molybdenum without any preconcentration step.
• The main benefits: low cost, sensitivity, rapid analysis.
• The method was efficiently applied to environmental samples such as river water.

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 × 103 L mol−1 cm−1. Under optimal conditions, the complex obeys Beer’s law from 0 to 9.9 μg mL−1. The relative standard deviation was 0.08% (for 11 samples, each containing 6 μg mL−1 molybdenum). Under the optimum conditions, the detection limit (3σ) was 17.7 μg L−1 for molybdenum without any preconcentration. The precision was determined from 30 results obtained for 4.80 μg mL−1 Mo(VI); the mean value of a molybdenum(VI) was 4.83 μg ml−1 with a standard derivation of 0.002 μg ml−1 molybdenum(VI).

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