A coating of poly(dimethylsiloxane) (PDMS) on a stir bar is typically used for sorptive extraction and preconcentration of nonpolar organic analytes from aqueous matrices. Here, we used sol–gel to synthesize three new coatings based on hydroxy-terminated PDMS crosslinked with 3-cyanopropyltriethoxysilane (CN) and phenyltriethoxysilane (PH) with three molar ratios of CN:PH (2:1, 1:1, and 1:2). The water contact angle of the coatings was below 90°. Cyanopropyl and phenyl groups were identified by infrared spectroscopy. The coatings were thermally stable up to 200°C. Also, they were stable to organic solvents and aqueous solutions at different pH. Glass stir bars were covered with the coatings to explore its potential application in stir-bar sorptive extraction. The test included polar antibiotics (sulfathiazole, sulfamethoxazole, trimethoprim, and chloramphenicol) dissolved in spiked water (pH 4.5) and organic solvent. Different experimental conditions were used to explore the capacity of the coatings to extract and preconcentrate the antibiotics. Unsatisfactory results of enrichment effect were obtained in aqueous solutions of antibiotics. In organic medium, the antibiotics were extracted and preconcentrated with the three coatings.

搅拌棒上的聚（二甲基硅氧烷）（PDMS）涂层通常用于吸附性萃取和预浓缩水性基质中的非极性有机分析物。在这里，我们使用溶胶-凝胶合成了三种新的基于羟基封端的PDMS的涂料，这些涂料与3-氰基丙基三乙氧基硅烷（CN）和苯基三乙氧基硅烷（PH）交联，摩尔比为CN：PH（2：1、1：1和1，三种） ：2）。涂层的水接触角低于90°。氰丙基和苯基通过红外光谱法鉴定。涂层在高达200°C的温度下具有热稳定性。而且，它们在不同的pH值下对有机溶剂和水溶液稳定。玻璃搅拌棒被涂料覆盖，以探索其在搅拌棒吸附萃取中的潜在应用。该测试包括极性抗生素（磺胺噻唑，磺胺甲恶唑，甲氧苄氨嘧啶，和氯霉素）溶解在加标水（pH 4.5）和有机溶剂中。使用不同的实验条件来探索涂层提取和预浓缩抗生素的能力。在抗生素水溶液中获得的富集效果不令人满意。在有机介质中，提取抗生素并用三种涂层预浓缩。