The spectrophotometric determination of trace molybdenum (VI) after collection and elution as molybdate ion on protonated chitin.

摘要

Collection and elution method for inorganic anion on protonated chitin has been applied to the spectrophotometric determination of molybdenum (VI). The Mo (VI) is collected as molybdate ion on a column of chitin in weak acidic medium which is easilyeluted with a small volume of 0.1 M ammonia buffer solution (pH 10). The Mo (VI) in the eluent is determined by bromopyrogallol red-Zephiramine method spectrophotometrically. Beer's law is obeyed over the concentration range Mo (VI) 0.1-0.8μg/ml eluentat 634 nm. The apparent molar absorptivity is 6 X 104 dm3 mol-1 cm-1. The tolerance limits for WO2-4, VO3-, CrO2-4 and Fe (III) is low, that is, 1-100 times that of Mo (VI), but some metal ions and common inorganic anions do not interfere in concentration range of 1000-5000 times that of Mo (VI). The present method can be applied to the determination of Mo (VI) in natural water samples.