Standardization of disodium dimethylglyoximate for the determination of nickel

Importance of the topic

Precise standardization of disodium dimethylglyoximate is essential for accurate nickel quantification in industrial, environmental and quality control laboratories. Thermometric titration offers a rapid, reagent-efficient approach for establishing the exact concentration of the complexing agent, ensuring reliable downstream analyses.

Objectives and overview

This study outlines the standardization of a 0.5 mol/L Na2DMG solution by thermometric titration against a certified 0.1 mol/L Ni(II) reference. The goal is to determine the true molarity of the titrant and demonstrate method performance under buffered conditions.

Methodology and instrumentation

Principle

• Na2DMG reacts in a 2:1 ratio with Ni(II), forming an exothermic complex in ammonia buffer.
• Pre-complexation with tartrate prevents interference from Al(III) and Fe(III).

Reagents

• 0.5 mol/L Na2DMG prepared by dissolving 153.6 g Na2DMG in 1 L water.
• NH3/NH4Cl buffer (17.5 g NH4Cl in 172 mL NH3, diluted to 250 mL).
• KNa tartrate at 450 g/L for metal interference suppression.
• 0.1 mol/L Ni solution obtained from purified NiO, acid‐dissolved and made to volume.

Instrumentation

• Thermometric titrator with Dosino dispensers for titrant, sample and buffer delivery.
• Magnetic stirrer operating at elevated speed to maintain homogeneity of precipitate.
• Titrotherm software for endpoint detection and data smoothing.

Results and discussion

Six titrations of Ni(II) aliquots (2.50–8.75 mL) yielded a linear calibration: y = 3.9972 x + 0.0353, R2 = 0.9999. Calculated Na2DMG molarity was 0.5004 mol/L, in excellent agreement with the target 0.5 mol/L. The clear exothermic temperature peaks against a falling baseline confirm robust endpoint detection even in the presence of viscous precipitate.

Benefits and practical applications

• High precision endpoint detection independent of color or turbidity
• Rapid analysis time and minimal reagent consumption
• Versatility for routine QC of complexing agents in metal analysis laboratories
• Reduced sample preparation through automated dosing

Future trends and possibilities

• Integration with flow injection systems for automated, high-throughput workflows
• Expansion to other metal–ligand systems using thermometric endpoints
• Development of greener buffer systems and lower-toxicity reagents
• Coupling with real-time data analytics and AI-driven endpoint prediction

Conclusion

Thermometric titration provides an accurate, reproducible method for standardizing disodium dimethylglyoximate. The demonstrated molarity closely matches theoretical values, confirming the approach as an effective tool for quality control in nickel determination.

Reference

No external references were provided in the source document.