Synthesis of a fluorophilic magnetic microporous organic network for selective enrichment of fipronil and ethiprole in milk and egg samples.

Considering the widespreadly use, large consumption, and serious environmental and health threats of phenylpyrazole insecticides (PPIs), development of a selective and sensitive method for accurate detection of their residuals in food samples is of great significance and challenging. Herein, depending on the hydrophobic and F-containing characteristics of PPIs, a novel fluorinated magnetic microporous organic network (FMMON) was designed and prepared for efficient and selective magnetic solid-phase extraction (MSPE) of two typical PPIs (fipronil and ethiprole) from milk and egg samples before the HPLC-UV determination. FMMON owned large specific surface area, multiple interaction sites, excellent magnetic separation performance and stability and exhibited good extraction and selectivity for fipronil and ethiprole through the specific F-F, hydrogen bonding, hydrophobic, and π-π interactions. Under optimal extraction conditions, the established FMMON-MSPE-HPLC-UV method provided wide linear ranges (0.1-1000 µg L-1), low limits of detection (0.03-0.05 µg L-1), large enrichment factors (96.2-99.7), low adsorbent consumption (4 mg), and short extraction time (6 min) for fipronil and ethiprole. This work revealed the bright future of fluorinated MONs in sample pretreatment of fluorinated contaminants in complex substrates.