COMPARISON OF TWO ORTHOGONAL LIQUID CHROMATOGRAPHIC METHODS FOR QUANTITATION OF SUGARS IN FOOD

Abstract

For analysis of seven sugars in various food samples, high-performance thin-layer chromatography ultraviolet detection (HPTLC-UV) was compared with high-performance liquid chromatography evaporative light scattering detection (HPLC-ELSD). The methods were orthogonal to each other with regard to separation and detection. The benchmarking of both methods showed HPTLC as highly suited or even better, if compared to HPLC, for quantitation of sugars in food samples with regard to capability of detection, intermediate precision, accuracy, and efficiency. The mean difference in the sugar content of both methods was 1.5% for the analyses of various food samples. For analysis of different chocolate sorts, the mean bias was 2.1%, if the sugar content was quantified by HPTLC and compared to the specified recipe values. This underlined the good accuracy of HPTLC. Calibration curves showed mean correlation coefficients of 0.9997 for HPTLC and 0.9938 for HPLC. The intermediate chromatographic precision [RSD (%), n = 2] for HPTLC ranged between 0.2 and 2.4% for sugars found in different chocolate sorts and between 0.2 and 6.5% for sugars found in a wider range of food products. For HPLC, it was between 0 and 12.9% for different food samples. The mean intermediate chromatographic precision was comparable over all chromatographic determinations [RSD (%) = 3.3% for HPTLC versus RSD (%) = 3.5% for HPLC]. The capability of detection of sugars by HPTLC-UV was improved, mainly by a factor of 8, if compared to HPLC-ELSD. With regard to the highly reduced analysis costs and analysis time, as well as less critical sample preparation and robust analysis, HPTLC is a very good alternative for quantitation of sugars in food. The HPTLC method transfer from food to biotechnological samples was demonstrated as well.

Keywords:

• benchmarking
• carbohydrates
• high-performance thin-layer chromatography
• mass spectrometry
• planar chromatography

ACKNOWLEDGMENTS

The authors want to thank the China Scholarship Council for the Scholarship; Dr. Dogan, Merck, Darmstadt, Germany for support regarding plate material and HPLC solvents; Ritter Sport, Waldenbuch, Germany for the chocolate samples; and CAMAG, Muttenz, Switzerland for support of instrumental equipment.

Notes

*www.rittersport.co.uk, retrieved 9th January 2011.