Abstract
The separation of 9 organophosphates (monocrotophos, quinalphos, triazophos, parathion-methyl, isofenphos-methyl, temephos, parathion, phoxim-ethyl, and chlorpyrifos) by high-performance thin-layer chromatography (HPTLC) with automated multiple development was studied. The HPTLC method was developed and validated for analysis of residues of phoxim-ethyl and chlorpyrifos in tea. The sample was extracted with acetonitrile and cleaned up by ENVI-CARB solid-phase extraction. The extract was directly applied as bands to glass-backed silica gel 60F254 HPTLC plates. The plates were developed with dichloromethanehexane (1 1, v/v) in a glass twin-trough chamber. Evaluation of the developed HPTLC plates was performed densitometrically. The results indicated that the detection limits of phoxim and chlorpyrifos were 5.0 109 and 1.0 108 g, respectively. Recoveries of the pesticides from tea by this analytical method were 90.7105.5%, and relative standard deviations were 7.313.5%. The precision and accuracy of the method were generally satisfactory for analysis of pesticide residues in tea.
Thin Layer Chromatographic analysis for detecting various bioactive compounds in the ethanolic leaf extracts of Thevetia peruviana (Pers.) K. Schum [Thevetia White]
