Analysis of maltooligosaccharides in honey samples by ultra-performance liquid chromatography coupled with evaporative light scattering detection

Abstract

We report the use of ultra performance liquid chromatography (UPLC) separation together with evaporative light scattering detection (ELSD) to effectively distinguish honey adulterated with maltooligosaccharides. UPLC separation utilizing a mobile phase with pure water and acetonitrile containing 0.2% triethylamine, resulted in enhanced separation and a running time of less than 6min. Also, only a simple liquid–liquid extraction was required for the sample pretreatment. This UPLC–ELSD method provides limits of quantifications (LOQs) from 0.30 to 0.60mg/g for the six maltooligosaccharides (maltose, maltotriose, maltotetraose, maltopentaose, maltohexaose and maltoheptaose) ranging from 15 to 2000μg/mL with excellent linearity(R2≥0.9914). This optimized method also offers a satisfactory intra-day precision of 2.4%–9.4%, inter-day precision of 5.5%–12.1% and accuracy of −7.7%–+11.4% at each level. We successfully applied this system for detecting maltooligosaccharide contamination in 290 honey samples collected from apiaries, supermarkets and traditional agri-product markets. Concentrations of the six maltooligosaccharides varied from undetectable to 14.1mg/mL. The lowest quantifiable concentration that could be detected by this established method was 0.132mg/mL. This study therefore demonstrates the reliability and potential use of the UPLC–ELSD technique in scrutinizing the authenticity of honey in the food processing industry.