Polyelectrolyte assembled graphene oxide coated silica composite as sorbent for solid-phase extraction of cinnamic acid and its derivatives

In this paper, a novel sorbent, poly(diallyldimethylammonium chloride) assembled graphene oxide coated silica (PDDA@GO@SiO2), was prepared and used as a sorbent for solid-phase extraction of cinnamic acid and its derivatives. The synthesized sorbent material was characterized by elemental analysis and field emission scanning electron microscopy, which confirmed the success of binding and assembling. The extraction properties of the resultant sorbent were evaluated by using cinnamic acid and its derivatives (caffeic acid, trans-4-hydroxycinnamic acid, isoferulic acid, 3,4-dimethoxycinnamic acid, cinnamic acid and 4-methylcinnamic acid) as the test analytes. Extraction efficiencies of PDDAGO@SiO2 were apparently superior to those of PDDA@SiO2 and commercial C18 sorbents. Under the optimal conditions, good linearities with R-2 ranging from 99.8% to 100% were obtained and the LODs and LOQs were found to be in the range of 0.5-2 mu g L-1 and 3-5 mg mu g L-1, respectively. The proposed method was successfully applied for the analysis of cinnamic acid in Gobi sherry and isoferulic acid in BuzhongYiqi pill.