Determination of nickel by titration with disodium dimethylglyoximate

Importance of the Topic

Thermometric titration offers a reliable approach for quantifying nickel concentration in various matrices. Its sensitivity and specificity for Ni(II) determination are critical for environmental monitoring, industrial process control and quality assurance. Moreover the method eliminates the need for end point indicators and allows automation.

Objectives and Study Overview

This application note presents a procedure to determine nickel in solution by titration with standard disodium dimethylglyoximate in buffered ammonia media. The study aims to optimize experimental parameters to achieve precise and accurate results for nickel contents ranging from 0.3 to 1 mmol.

Applied Instrumentation

• Thermometric titrator equipped with a temperature sensor
• Dosino dispensing units for titrant, buffer and tartrate solutions
• Magnetic stirrer set to high speed to maintain homogeneity
• Volumetric flasks for solution preparation
• Titrotherm software for data acquisition and endpoint detection

Methodology and Reagents

• Titrant 0.5 mol per liter disodium dimethylglyoximate prepared by dissolving 153.6 grams of reagent in deionized water to 1 liter
• Buffer ammonia ammonium chloride buffer prepared by combining 17.5 grams NH4Cl and 172 milliliters concentrated NH3 solution diluted to 250 milliliters
• KNa tartrate solution at 450 grams per liter used to mask Al(III) and Fe(III) interferences

The sample aliquot is adjusted to yield 0.3 to 1 mmol of Ni and diluted to approximately 45 milliliters including buffer and tartrate. Titration proceeds at a delivery rate of 2 milliliters per minute with one exothermic endpoint recorded. High stirrer speed and increased solution volume mitigate the impact of viscous Ni dimethylglyoximate precipitate on the endpoint.

Main Results and Discussion

Titration of high purity nickel solutions each aliquot equivalent to 0.06372 grams of sample yielded an average nickel content of 78.44 percent with a standard deviation of 0.09 percent over 12 replicates. The thermometric titration plot shows a background temperature decline due to ammonium buffer neutralization followed by an exothermic peak corresponding to complex formation. Second derivative data enhance endpoint detection accuracy.

Benefits and Practical Applications of the Method

• High precision and reproducibility without color indicators
• Automation capability reduces operator variability and labor
• Wide applicability for purity assessment and routine quality control in metal processing industries
• Simple sample preparation with effective masking of interfering metal ions

Future Trends and Opportunities

• Integration of microcalorimetric sensors for rapid field analysis
• Expansion to multi element titrations using advanced data deconvolution
• Development of inline monitoring systems for continuous process control
• Enhanced software algorithms for real time endpoint prediction and diagnostics

Conclusion

The thermometric titration method using disodium dimethylglyoximate in buffered ammonia offers a robust, accurate and automated approach for nickel determination. With minimal interference and high reproducibility this technique is well suited for industrial and environmental analytical laboratories.

References

• Thermo Scientific Application Note No H-049 Determination of nickel by titration with disodium dimethylglyoximate