| Summary: | Background: Environmental contamination with nickel is increasing due to the discharge of industrial effluents and other anthropogenic activities. Therefore, the improvement of methods for monitoring nickel concentration is of great value. The dimethylglyoxime (DMG) method is used to determine the nickel concentration in aqueous solutions. This method requires the oxidation of Ni(II) to Ni(IV) by bromine water before adding DMG, which is necessary to complete color development. The original method uses more than 50 mL of final reagent volume per sample. In this study, a volume reduction of the DMG method was performed. Results: A volume reduction of 1 mL per sample was successfully achieved for the DMG method. The working range was 0 - 10 mg Ni(II) L−1. The specified limits of detection and quantification (LOQ and LOD) were 1.18 and 0.41 mg L−1 respectively. A comparative analysis with atomic absorption spectroscopy (AAS) showed no significant differences between both methods for nickel determination. The modified DMG method was effective for the measurement of nickel in experimental samples from a bioremediation assay. Conclusion: The modified DMG method offers considerable advantages. The modified method reduces the volume of reagents used from 50 mL to just 1 mL. The requirement of smaller volume of each reagent is economically favorable, and consequently the amount of passive waste generated is reduced. It is easily reproducible in a laboratory with access to a spectrophotometer and simple reagents. In addition, the possibility to measure samples from bioremediation assays is an advantage.
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