Determination of Sugar Alcohols in Confections and Fruit Juices by High-Performance Anion-Exchange Chromatography with Pulsed Amperometric Detection

Importance of the Topic

The accurate determination of sugar alcohols such as sorbitol and mannitol in confectionery and fruit juices is essential for quality control, regulatory compliance, and nutritional labeling. These alditols provide sweetness without the caloric impact of sugars but require precise quantitation due to their laxative and diuretic effects at high intake levels.

Objectives and Study Overview

This work aimed to establish a robust high-performance anion-exchange chromatography method with pulsed amperometric detection (HPAEC-PAD) for simultaneous separation and quantification of sugar alcohols and related carbohydrates in food matrices. The focus was on performance evaluation of the Thermo Scientific Dionex CarboPac MA1 column under elevated sodium hydroxide conditions.

Methodology and Instrumentation

Sample preparation varied by matrix:

• Dietetic hard candy: dissolved in water and diluted 1:1000.
• Apple juice: diluted 1:1000.
• Chewing gum extract: sonicated, cartridge purified, filtered, and diluted 1:1000.

Chromatographic system comprised a gradient pump, liquid chromatography module, and ED40 pulsed amperometric detector configured for gold electrode detection with a three-step potential waveform. The CarboPac MA1 column (4 × 250 mm) operated at ambient temperature using water (Eluent A) and 1 M NaOH (Eluent B) at 0.4 mL/min. Detector settings were optimized for carbohydrate oxidation and surface regeneration.

Results and Discussion

Sugar alcohols eluted according to pKa values, with higher pKa compounds eluting first. Calibration exhibited linearity (r2 > 0.995) over three orders of magnitude and detection limits down to 2 pmol for key alditols. Chromatograms demonstrated baseline resolution of sorbitol, mannitol, xylitol, inositol, and mono-/disaccharides. Application to real samples revealed:

• Hard candy: 2.70 g sorbitol and 0.05 g mannitol per 3.4 g drop.
• Apple juice: 1.86 g sorbitol, 8.22 g glucose, 18.8 g fructose, and 7.76 g sucrose per 237 mL.
• Chewing gum: 218 mg glycerol, 1140 mg sorbitol, and 280 mg mannitol per 2.7 g stick.

Benefits and Practical Applications

The method delivers high sensitivity and selectivity without derivatization or postcolumn reagents. Ambient temperature operation minimizes column wear and simplifies setup. PAD provides low detection limits and resistance to matrix interferences. The CarboPac MA1 column’s high-capacity anion-exchange capacity enables flexible pH tuning for optimal separation of closely related carbohydrates.

Future Trends and Applications

Emerging directions include extending HPAEC-PAD methods to physiological fluids, tissue extracts, and complex glycoconjugate analyses. Advances in electrode materials and automated sample cleanup will further enhance sensitivity and throughput. Integration with high-resolution mass spectrometry may expand structural elucidation of novel sugar derivatives.

Conclusion

The Thermo Scientific Dionex CarboPac MA1 column coupled with pulsed amperometric detection provides a robust, sensitive, and flexible platform for sugar alcohol analysis in foods. Its high pH operating range, ambient temperature stability, and excellent reproducibility make it the method of choice for dietetic product testing and nutritional quality control.

Reference

1. Shaw PE. CRC Handbook of Sugar Separations in Foods by HPLC; CRC Press, Boca Raton, FL, 1988.
2. Solomons TWG. Organic Chemistry, 2nd ed.; John Wiley & Sons, New York, 1980.
3. Thermo Fisher Scientific. Technical Note 21: Optimal Settings for Pulsed Amperometric Detection of Carbohydrates Using the Dionex ED40 Detector; Sunnyvale, CA, 2013.
4. Coppola ED. Food Technology. 1984;38(4):88-91.
5. Thermo Fisher Scientific. Technical Note 20: Analysis of Carbohydrates by High-Performance Anion-Exchange Chromatography with Pulsed Amperometric Detection; Sunnyvale, CA, 2013.