ZIF-67 as a thermally desorbable analytical sorbent for sub-ppbv quantification of hazardous volatile organic...

This study presents the first application of ZIF-67, a cobalt-based zeolitic imidazolate framework, as a thermally desorbable analytical sorbent for the quantitative monitoring of atmospheric volatile organic compounds (VOCs) via thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS). The ZIF-67 synthesized by a simple solution-phase method exhibited a BET surface area of 1516 m² g^-1, a uniform microporous structure with sodalite topology, and thermal stability up to ∼500 °C, all of which are favorable physicochemical properties for use in TD-GC-MS-based analysis. Method validation was performed across four key parameters-response factor, linearity, precision, and limit of detection-for 24 target VOCs with diverse functional groups, including alkanes, aldehydes, ketones, esters, alcohols, aromatic hydrocarbons, carboxylic acids, phenols, amines, and sulfides. Among the activation temperatures evaluated (240-320 °C), 280 °C was identified as the optimal condition. Comparative validation against commercial sorbents (Tenax TA and the Carbopack series) confirmed that ZIF-67 sorbent tubes achieved performance equivalent to or superior to that of commercial sorbents for aromatic (BTX) and ketone/ester compound classes, with xylene isomers yielding the best overall performance among all evaluated sorbent tubes (RSD ≤ 1.8%). Field validation using ambient BTX samples at concentrations ranging from 0.09 to 1.08 ppbv demonstrated quantitative agreement with Tenax TA, with a mean difference of 7.3%, confirming real-world applicability. The markedly lower production cost of ZIF-67 relative to commercial sorbents, combined with the potential recovery of cobalt from spent lithium-ion batteries, positions ZIF-67 as a competitive and sustainable material for atmospheric VOC monitoring across analytical chemistry, environmental engineering, and environmental materials science.