Abstract

Supercritical fluid extraction (SFE) is a promising method of extraction for pesticide residues in fruits and vegetables. A rapid and high percetage of recoveries extraction of cypermethrin insecticides from fresh yardlong bean, carrot and eggplant vegetables matrixs using drying agent and SC-CO₂ was developed in this study. In vegetable samples, which typically contain 80 - 95% water, but samples dry with Na₂SO₄ showed 96 - 105% recoveries in SFE. Moreover, the performance of drying agents (Na₂SO₄) and their combination such as Na₂SO₄ –H₂O (6.7 + 1),Na₂SO₄ – H₂O (2 + 1) and Na₂SO₄ – H₂O (1 + 1) were evaluated. Na₂SO₄-H₂O (1 + 1) was shown moisture conveyanced by SFE/mg highest (93) performance.Cypermethrin recovered from yardlong bean and carrot with critical pressure, P_C at 20 Ibs and critical temperature, T_C 40°C. On the other hand, the recovery rate of similar insecticides from egg plant was 96% with P_C at 31.5 Ibs and 45°C in T_C.The recovery rate in yardlong bean matrices was 100%; 105% was in carrot matrix. The retention time (t_R) was 49.6 min of cypermethrin standard and similar t_R was found in formulated. The lowest detectable limit (LDL) of cypermethrin insecticides was 0.02 µg/mL with gas chromatography-electron capture detection (GC-ECD).GC-ECD temperature was of injection port and detector 280 and 300°C, respectively, with split less. However, the method is useful to recover non-polar insecticides from the fresh vegetable; thus, further research could be continued with co-solvents and different drying agents to recover the polar residues from different types of fresh vegetables.

Key words: Lowest detectable limit, retention time, drying agents, recovery rate.

Abbreviation

SFE, Supercritical fluid extraction; P_C, critical pressure; T_C, critical temperature; t_R, average retention time; R², linear regression; LDL, lowest detectable limit; GC-ECD, gas chromatography-electron capture detection; GC-ECD, chromatography coupled to electron capture detector; HPLC, high performance liquid chromatography; GPC, gel-permeation chromatography.