We evaluated the effectiveness of new cleanup agents (S-NH2 and S-Si) compared with other previously reported cleanup agents (octadecylsilane, graphitized carbon, aminopropyl and silica gel) for removal of interfering substances such as catechin and caffeine prior to analysis of pesticide residues in tea. S-NH2 and S-Si were highly efficient in removal of catechin and caffeine, respectively. Recoveries of 80 pesticides using S-NH2 and S-Si were tested, and more than 70% of pesticides showed recovery greater than 70%. These results indicate that S-NH2 and S-Si agents will be useful for analysis of pesticide residues in tea.
Keywords: caffeine; catechin; pesticide residue; tea.