Colorimetric Detection of Carcinogenic Alkylating Fumigants on Nylon 6 Nanofibrous Membrane. Part II: Self-Catalysis of 2-Diethylaminoethyl Modified Sensor Matrix for Improvement of Sensitivity.

Nylon 6 nanofibrous membrane (N6NFM) was covalently modified with 2-diethylaminoethylchloride (DEAE-Cl) to provide self-catalytic functions to facilitate the formation of color compounds in reactions of 4-( p-nitrobenzyl)pyridine with alkylating fumigants. The 2-diethylaminoethyl group on the DEAE-Cl modified N6NFM (DEAE@N6NFM) enables effective elimination of hydrohalogenic acids from intermediates that were formed from reactions between the alkylating fumigants and NBP, and consequently improve their detection sensitivities, especially for 1,3-dichloropropene at room temperature. Moreover, the DEAE@N6NFM can be recycled and reused multiple times without obvious loss in the sensing functions or any noticeable material damage. The naked-eye detection limits of the sensor to 1,3-dichloropropene, methyl iodide and methyl bromide on the DEAE@N6NFM are improved to 0.2 ppm, 0.1 ppm, and 0.1 ppm, respectively, which are much lower than their occupational exposure limits. The reaction mechanism is demonstrated through a computational method by analyzing the thermodynamics of the reaction. The modification of the DEAE@N6NFM also provides an insight into the development of functionalized materials with improved reactivities for versatile sensing applications.