Abstract:The use of retention index (Kovats index) to detect adulteration of honey with starch syrup was studied. After dissolving the honey sample in water, fructose and glucose were removed by Gel (Bio-Gel ? Gel P-2) size-exclusion, oligosaccharides were concentrated, separated, and directly identified by anion-exchange chromatography using an electrochemical detector. Linear maltooligosaccharides are formed by condensation of glucose monomers, similar to n-alkanes. Using the chromatographic peaks of maltooligosaccharide (maltose to maltoheptaose) standards as reference, the retention indices of maltotetraose, maltopentaose, maltohexaose, and maltoheptaose were set at 400, 500, 600, and 700, respectively, while the retention index value of sample peak was calculated based on the retention time. The results showed similar functional retention index values for maltose standard samples as compared with fructose syrup, pure honey containing fructose syrup, and in some commercial honey samples, while they were not found in pure honey samples. This approach can be used to detect adulteration of honey with 1% sensitivity, and was validated using deliberately adulterated honey samples.
