Voltammetric detection of MoO2−4 at a modified carbon paste electrode containing chitin

The voltammetric determination of MoO2−4 after accumulation on a carbon paste electrode (CPE) modified with chitin was investigated. MoO2−4 can be selectively accumulated on the electrode based on the electrostatic interaction with the acetylamide group in chitin in 0.1 M acetate buffer (pH 4.3) without the need to apply a potential. The oxidation peak of molybdenum(IV) was observed at −0.58 V (vs. Ag/AgCl) in 0.1 M acetate buffer (pH 4.3) by scanning the potential in a positive direction. The calibration curve of MoO2−4 was linear in the range from 1 × 10−7 to 5 × 10−6 M for an accumulation of 20 min. Coexisting ions hardly affect the voltammetric measurement because the accumulation solution differed from the measurement solution. The presented method was applied to the determination of MoO2−4 in sea water.