Received: March 15, 2021. Editorial decision: December 1, 2021 © The Author(s) 2022. Published by Oxford University Press. All rights reserved. For permissions, please email: journals.permissions@oup.com Journal of Chromatographic Science, 2022, 60, 9, 887–896 https://doi.org/10.1093/chromsci/bmab140 Advance access publication date 30 December 2021 Article Online Solid-Phase Extraction of Prometon and Prometryne Using MIL-101(Cr) as Sorbent before Gas Chromatographic Analysis: A Computational and Experimental Study and Comparison between Splitless and PTV Inlets Mahsa Torabizadeh, Kourosh Tabar-Heydar * and Seyyed Hamid Ahmadi Faculty of Clean Technologies, Chemistry and Chemical Engineering Research Center of Iran, Pajohesh Blvd, 17th Km of Tehran-Karaj Highway, Tehran, Iran *Author to whom correspondence should be addressed. Email: ktabarh@ccerci.ac.ir Abstract In this study, prometryne and prometon were extracted and preconcentrated from aqueous media using an online solid-phase extraction– thermal desorption method coupled with gas chromatography–flame ionization detector (GC-FID), equipped with two different inlets: split and programmable temperature vaporizer (PTV). For this purpose, the applicability of Tenax and a metal–organic framework were investigated as solid-phase sorbents. Several effective parameters on the extraction efficiency, such as the amount of sorbent, sample volume, sample pH and thermal desorption procedure were optimized. The analytical performance of the proposed methods showed an excellent linear dynamic range for prometon and prometryne (0.25–100 μg/L) and relative standard deviation less than 4.01%. Moreover, the detection limits below 0.20 and 0.35 μg/L were determined for prometon and prometryne, respectively. Additionally, molecular docking was applied to clarify the adsorption nature and binding energy of MIL-101(Cr) toward the studied analytes, which indicated an appropriate correlation between computational and experimental results. Finally, the proposed method was developed and validated for prometon and prometryne and successfully applied for their extraction from agricultural water, spiked with prometon and prometryne through its direct introduction into the GC inlet. Introduction Triazine herbicides are among triazole pesticides with an extensive application as selective herbicides to control broadleaf and grassy weeds in diverse crops. The excessive use of these herbicides has resulted in their release in soils (1–3), groundwaters (4), surface waters (5, 6) and foods (7– 9). Triazine herbicides have been considered as one of the most important classes of persistent organic pollutants (POPs) due to their environmental persistence, bioaccumulation, semivolatility and high toxicity. Among them, prometon has been applied for total vegetation control on industrial sites, noncrop areas of the farms, under asphalt and to a small extent by homeowners (10). Prometryne is used as a preemergence herbicide (before the targeted weed germinates) to control annual and perennial grasses and annual broad- leaved weeds in the fields of wheat, cotton, rice and vegetables (11). The geological surveys have demonstrated prometon as the most commonly detected herbicide in surface water and groundwater of urban areas and the third and fourth most commonly detected herbicide in groundwater and surface water of agricultural areas, respectively (10, 11). As the most common and widespread sample preparation technique, liquid–liquid extraction (LLE) has been applied to separate compounds or metal complexes. This method relies on the relative solubility of the compounds in two different immiscible liquids, usually water (polar) and an organic solvent (nonpolar). For acquiring more selectivity, the solid-phase extraction (SPE) technique has been developed as an alternative extraction technique with a broad field of applications (10–12). SPE exploits the difference in analyte interferents’ affinity for a solid-phase (sorbent) in a liquid matrix to separate the target analyte from the interferents. SPE can be applied in different approaches: off-line and online systems. In off-line methods, the SPE unit is not directly connected to LC or GC, while in online systems, the SPE device is inserted into the liquid or gas stream of the chromatograph, implying that it is part of the chromatographic system (13, 14). Due to the nature of most routine chromatographic columns, direct analysis of water samples with capillary GC is a challenging task in aqueous samples analysis. Direct injection of water dissolved the phase and caused the phase to elute from the columns. Consequently, column damage, change in retention time, change in selectivity and increase in column bleed are the most common problems caused by direct injection of aqueous samples. Schomburg et al. applied a polar coated precolumn to inject 1–5 μL of an aqueous sample directly into the capillary GC system via a split injector (15). They also used a dual-oven system to inject up to 200 μL water on a GC precolumn packed with Tenax, a porous polymer resin based on 2, 6-diphenylene oxide, and they managed to analyze the compounds at the 0.1 mg/L level with a capillary column after the introduction of the analytes in splitless mode. In another research, van Hout et al. used a solid-phase extraction method combined with thermal desorption and GC analysis to determine drugs in urine Downloaded from https://academic.oup.com/chromsci/article/60/9/887/6490091 by guest on 09 November 2022