College of Chemistry and Materials Engineering, Hunan University of Arts and Science, Changde, 415000, China; College of Chemistry, Zhengzhou University, Zhengzhou 450001, China; Henan Institute of Science and Technology, Xinxiang 453000, China.
College of Chemistry, Zhengzhou University, Zhengzhou 450001, China; Henan Institute of Science and Technology, Xinxiang 453000, China.
J Chromatogr A. 2022 May 10;1670:462948. doi: 10.1016/j.chroma.2022.462948. Epub 2022 Mar 9.
Metal wires have been widely used as substrates for solid-phase microextraction (SPME) fibers instead of commonly fragile silica fibers, but complicated coating modification of their surface is required. Herein, a series of brass wires were soaked in an acidic iron trichloride solution with ultrasonication, which etched the brass surface through a redox reaction. The surface wettability of the pristine brass wire was transformed from hydrophobic to hydrophilic owing to the formation of micro/nanoscale hierarchical structures. After modification with n-octadecanethiol (ODT) and 2-naphthalenethiol (NT), respectively, both wires exhibited superhydrophobicity. Characterization of the resulting wires was conducted using SEM and EDS, and the surface wettability was measured by a contact angle goniometer using identical brass meshes. To build an in-tube SPME-high-performance liquid chromatography (HPLC) online system, the extraction tube was connected with HPLC equipment by replacing the sample loop of a six-port valve. Four types of wires, including the pristine hydrophobic brass wire, the hydrophilic wire after chemical etching, and both superhydrophobic wires, were comparatively applied to the extraction of six estrogens. The optimized extraction conditions were a sample volume of 60 mL, an injection rate of 2 mL/min, and a desorption time of 2 min at a flow rate of 1 mL/min. The results showed that the highest estrogen extraction efficiency was obtained using the superhydrophobic wire modified by NT, with the enrichment factors in the range of 36-350. Furthermore, the superhydrophobic NT wire exhibited a higher extraction efficiency than the ODT wire with identical superhydrophobicity. This demonstrated that the higher extraction efficiency was mainly dependent on π-π interactions between the sorbent containing naphthalene rings and the target compounds containing benzene rings, rather than surface wettability.
金属丝已被广泛用作固相微萃取（SPME）纤维的基底，而不是通常易碎的二氧化硅纤维，但需要对其表面进行复杂的涂层修饰。在此，一系列黄铜丝在超声作用下浸入酸性三氯化铁溶液中，通过氧化还原反应蚀刻黄铜表面。由于微/纳米级分层结构的形成，原始黄铜丝的表面润湿性从疏水性转变为亲水性。分别用十八硫醇（ODT）和 2-萘硫醇（NT）修饰后，两根金属丝均表现出超疏水性。使用 SEM 和 EDS 对所得金属丝进行了表征，并使用相同的黄铜网通过接触角测角仪测量了表面润湿性。为了构建管内 SPME-高效液相色谱（HPLC）在线系统，通过用六通阀的样品环代替，将萃取管与 HPLC 设备连接。将四种类型的金属丝，包括原始疏水性黄铜丝、化学蚀刻后的亲水性金属丝以及两种超疏水性金属丝，分别应用于六种雌激素的萃取。优化的萃取条件为 60 mL 样品体积、2 mL/min 进样速度和 1 mL/min 洗脱速度下 2 min 的洗脱时间。结果表明，使用 NT 修饰的超疏水性金属丝获得了最高的雌激素萃取效率，其富集因子在 36-350 范围内。此外，超疏水性 NT 金属丝的萃取效率高于具有相同超疏水性的 ODT 金属丝。这表明较高的萃取效率主要取决于含有萘环的吸附剂与含有苯环的目标化合物之间的π-π相互作用，而不是表面润湿性。
