Preparation of an Al2O3/SiO2 core-shell composite material for solid phase extraction of flavonoids

In this paper, a novel sorbent, nano-Al2O3 coated mesoporous silica (Al2O3/SiO2), was prepared and used as a sorbent for solid-phase extraction of flavonoids. The synthesized sorbent material was characterized by Xray photoelectron spectroscopy, energy dispersive spectroscopy and inductively coupled plasma emission spectrometry. The extraction properties of the resultant sorbent were evaluated by using four flavonoids (myricetin, quercetin, luteolin and kaempferol) as the test analytes. The extraction efficiencies of Al2O3/SiO2 were apparently superior to those of commercial C18 sorbents. Under optimal conditions, good linearities with R-2 ranging from 98.8% to 99.8% were obtained and the LODs and LOQs were found to be in the range of 0.5-1 mu g L-1 and 2.5-3 mu g L-1, respectively. The proposed method was successfully applied for the real sample analysis of wild honey and red grape juice.