Determination of selected phenolic compounds in quince jams by solid-phaseextraction and HPLC

With the purpose of improving an analytical method for the determination of selected phenolic compounds in quince jams, a comparative study of recover ies by two different non-polar sorbents, Isolute C18 non end-capped (NEC) a nd Isolute C18 end-capped (EC), was performed. Significant differences in t he recovery percentages were found. The results suggest that Isolute C18 (N EC) is the most suitable for the recovery of the selected phenolics from qu ince jams, when 1% of methanol was added to the samples. The reversed-phase High-Performance Liquid Chromatography/Diode Array Detec tor (HPLC/DAD) procedure is rapid, sensitive, reproducible, and accurate. T he improved sample preparation was simple, involving only a C18 Solid-Phase Extraction (SPE) purification step. The detection limit values for phenolic compounds were between 0.1 and 1.6 mug mL(-1) and the method was precise. As a general rule, the recovery valu es were high, except for arbutin. This technique can also be useful in the evaluation of commercial quince ja ms genuineness.