Preparation Of Three Dimensionally Honeycomb Mg-Al Layered Double Oxides And Its Application In Analysis Of Pesticide Residues In Tea

Pesticide residues exceeding standard in tea is a widespread problem of the world's attention, containing organochlorine pesticides (OCPs), organophosphorus pesticides (OPPs), and pyrethroids, which have been confirmed to be a potential health risk for consumers. Therefore, it is significant to employ a rapid, efficient and economic method for the determination of the residues from tea.Tea matrix is relatively complex, therefore it needs to develop a new type of adsorption packing to improve the process of purification.In this work, three dimensionally honeycomb Mg-Al layered double hydroxide was synthesized by template method. The structures and morphologies of Mg-Al LDH were investigated by the characterization of IR, SEM and XRD. The conditions of controllable morphology Mg-Al LDH have been established.In this research, three dimensionally honeycomb Mg-Al layered double oxide (TDH-Mg-Al-LDO) combined with graphitized carbon black (GCB), used as a novel solid phase extraction sorbent, applying in simultaneous determination of 15 pesticide residues in tea coupled with GC-MS. Compared with different type of SPE column, it showed that TDH-Mg-Al-LDO exhibited great advantages in the extraction of 15 pesticide residues from tea, which was seldom reported before. Different experiment conditions, such as combination order of Mg-Al-LDO and GCB, dosage of sorbents, type and volume of eluting solvent were thoroughly studied and optimized. The limits of detection (LODs) of 15 pesticides ranged from 0.9 to 24.2 ng/g. The recoveries using this method at three spiked concentration levels range from 71.1 to 119.0%. The relative standard deviation (RSD) was from 0.1 to 7.6% in all case. The result indicated that the proposed analytical method had been successfully applied for the simultaneous determination of 15 pesticide residues in commercial tea.