Determination of Sucralose in Reduced- Carbohydrate Colas using High-Performance Anion-Exchange Chromatography with Pulsed Amperometric Detection

Importance of the Topic

Sucralose is a widely adopted non nutritive sweetener in reduced carbohydrate and diet beverages. Accurate measurement of sucralose at low levels within high concentrations of sugars poses a significant analytical challenge. Standard UV and refractive index detection methods lack required sensitivity or selectivity in such complex matrices. High performance anion exchange chromatography coupled with pulsed amperometric detection provides enhanced sensitivity for carbohydrates and related compounds under strongly basic conditions.

Objectives and Study Overview

The primary objective was to develop a robust HPAE PAD method for quantifying sucralose in reduced carbohydrate cola beverages. Key goals included optimizing sample dilution and eluent composition to resolve sucralose from excess fructose and sucrose, while ensuring detection of low micro molar levels of sucralose. The method was applied to two commercial reduced carbohydrate colas and a low carbohydrate fruit beverage for method validation and practicality assessment.

Methodology and Instrumentation

Samples were degassed by freezing and thawing, then diluted to minimize overload of native sugars. A 100 fold dilution was found optimal for cola products, while a 50 fold dilution was sufficient for the low carbohydrate fruit beverage.

Eluent A consisted of 100 mM sodium hydroxide with 90 mM sodium acetate. A column wash solution of 100 mM sodium hydroxide with 800 mM sodium acetate was employed after extended runs to maintain retention stability. All eluents were prepared with high purity water, free of carbonate and particulates, and filtered through 0.2 micron nylon membranes.

Instrumentation featured a Dionex ICS 2500 system with GP50 gradient pump, CarboPac PA20 analytical and guard columns, ED50A electrochemical detector operating with waveform A for carbohydrate analysis, and disposable gold working electrodes. Chromeleon workstation controlled data acquisition and processing.

Main Results and Discussion

Isocratic separation at 0.5 mL per minute and 30 degrees Celsius achieved baseline resolution of sucralose from fructose and sucrose within ten minutes. Retention time for sucralose was approximately six minutes. Calibration over a concentration range 0.1 to 10 micro molar yielded linear response with correlation coefficients above 0.999.

Applied to commercial reduced carbohydrate colas, the method determined sucralose concentrations of 25.6 plus minus 1.9 micro molar in Brand A and 188 plus minus 16 micro molar in Brand B after accounting for dilution. Spike recovery studies demonstrated recoveries near 100 percent for both samples, confirming method accuracy. For the low carbohydrate peach citrus beverage, no significant interference from native sugars was observed and sucralose concentration was measured at 391 plus minus 4 micro molar using a 50 fold dilution.

Benefits and Practical Applications

• The developed method provides high sensitivity and selectivity for sucralose in complex beverage matrices
• Sample dilution protocols effectively mitigate column overload from high sugar content
• Commercial instrumentation and disposable electrodes ensure reproducible and low maintenance operation
• Spike recovery and calibration data confirm accuracy and precision suitable for quality control laboratories

Future Trends and Opportunities

• Extension of the approach to other food and beverage matrices containing multiple sweeteners and additives
• Implementation of gradient elution strategies to shorten analysis time for samples with minimal interference
• Miniaturized or high throughput configurations for routine screening in industrial quality control
• Development of automated sample preparation workflows to further increase laboratory productivity

Conclusion

A robust HPAE PAD method was established for accurate determination of low level sucralose in reduced carbohydrate colas. Optimized eluent conditions and sample dilution provided clear separation from major sugar interferents. The approach demonstrated excellent linearity, precision, and recovery, supporting its use in routine quality testing of diet and reduced sugar beverages.

Reference

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