Development of an online μ-matrix cartridge extraction method for fipronil extraction in contaminated soils

Nowadays, environment fate and behavior of pesticides in soil is still not fully understood due to the lack of standardized soil extraction method. In this work, a soil-filled micro-matrix cartridge was online combined with high performance liquid chromatography-mass spectrometry (HPLC-MS) through a six-way valve for the simultaneous extraction and determination of residual fipronil in soil. Compared with conventional extraction methods, such as hydroxypropyl-β-cyclodextrin (HPCD) extraction, shaking extraction, ultrasonic-assisted extraction (UAE), three-step extraction and matrix solid phase dispersion (MSPD), the novel, miniaturized, and integrated online micro-matrix cartridge extraction (online μ-MCE) method exhibited better performance in terms of desorption efficiency (99.4%), analysis time, solvent consumption, sensitivity, and automation. In sequential extraction, online μ-MCE could further desorb fipronil from the extracted soil with the percentage of 1.05%-58.55%. High recovery of 92.69% obtained for the ISO certificated test-soil verified the satisfactory accuracy of the method. Besides, its wide universality was also validated in three variables: 1) various pesticides-soil interactions, 2) four types of compounds (aromatic hydrocarbons, carboxylic acids, alcohols and aldehydes), and 3) three types of soils (sandy soil, silty loam and silty clay). The superior desorption capacity might be attributed to the instantaneously increased high-pressure, continuous flow dynamic desorption and short residence time. The present encouraging findings might shed light on new ways to develop a mild, highly efficient, reliable and one-fit-all extraction method toward pesticide contaminated soil.