Alkylating fumigants are widely used in agricultural production for the control of soil-borne pests, but the acute toxicity and carcinogenicity of these chemicals pose a health threat to farm workers as well as residents. A nanofibrous membrane-based colorimetric sensor relying on the nucleophilic substitution reaction of 4-(<i>p</i>-nitrobenzyl) pyridine (NBP) is introduced for the convenient and portable detection of alkylating fumigants. Comparing with the traditional use of NBP in detecting alkylating agents, this sensor system achieves a ppb-level detection sensitivity toward alkylating fumigant gases without a high-temperature incubation or the addition of extra bases. Moreover, nylon 6 nanofibrous membrane was covalently modified with 2-diethylaminoethylchloride (DEAE-Cl) to provide self-catalytic functions to facilitate formation of color compounds in reactions of 4-(<i>p</i>-nitrobenzyl)pyridine (NBP) with alkylating fumigants, especially for 1,3-dichloropropene. The mechanisms of the detection reaction and catalytic functions were studied with computational methods, and the results comprehensively prove the proposed optimized detection mechanisms. The detection limit of methyl iodide, methyl bromide, and 1,3-dichloropropene successfully reaches to the limiting exposure concentrations (PEL or REL) with a naked-eye detectable color difference within 5 or 10 min with a dynamic detection procedure. The designed sensing system is promising for a real-time monitoring of the air quality related to alkylating fumigants in the environment, especially in agricultural and industrial areas.

Colorimetric detection of carcinogenic alkylating fumigants on nylon 6 nanofibrous membrane with self-catalytic function

2019 Fall National Meeting

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