Institute of Chemistry of São Carlos, University of São Paulo, São Carlos, Brazil.
J Sep Sci. 2018 May;41(10):2237-2244. doi: 10.1002/jssc.201701148. Epub 2018 Apr 6.
Sulfonamides are antibiotics widely used in the treatment of diseases in dairy cattle. However, their indiscriminate use for disease control may lead to their presence in tissues and milk and their determination requires a sample preparation step as part of an analytical approach. Among the several sample preparation techniques available, those based upon the use of sorptive materials have been widely employed. Recently, the application of ionic liquids immobilized on silica surfaces or polymeric materials has been evaluated for such an application. This manuscript addresses the evaluation of silica-based ionic liquid obtained by a sol-gel synthesis process by basic catalysis as sorbent for online solid-phase extraction with liquid chromatography and electrospray ionization time-of-flight mass spectrometry for sulfonamides determination. Infrared vibrational spectroscopy confirmed the presence of the ionic liquid on the silica surface, suggesting that the ionic liquid was anchored on to the silica surface. Other sorbents varying the ionic liquid alkyl chain were also synthesized and evaluated by off-line solid-phase extraction in the sulfonamide extraction. As the length of the alkyl chain increased, the amount of extracted sulfonamides decreased, possibly due to a decrease in the electrostatic interaction caused by the reduction in the polarity, as well as the presence of a hexafluorophosphate anion that increases the hydrophobic character of the material. The use of 1-butyl-3-methylimidazolium hexafluorophosphate as a selective ionic liquid sorbent enabled the isolation and sulfonamide preconcentration in bovine milk by online solid-phase extraction with liquid chromatography and electrospray ionization time-of-flight mass spectrometry. The limit of quantification for the method developed was 5-7, 5 μg/mL, with extraction recoveries ranging between 74 and 93% and intra- and interassay between 1.5-12.5 and 2.3-13.1, respectively.
磺胺类药物是广泛用于治疗奶牛疾病的抗生素。然而，它们被滥用于疾病控制可能导致它们在组织和牛奶中存在，并且需要样品制备步骤作为分析方法的一部分来确定其存在。在几种可用的样品制备技术中，基于吸附材料的技术得到了广泛的应用。最近，已经评估了将离子液体固定在硅胶表面或聚合材料上用于此类应用的情况。本文介绍了通过碱性催化溶胶-凝胶合成过程获得的基于硅胶的离子液体的评估，该离子液体用作在线固相萃取的吸附剂，与液相色谱和电喷雾电离飞行时间质谱联用，用于磺胺类药物的测定。红外振动光谱证实了离子液体存在于硅胶表面，表明离子液体已锚定于硅胶表面。还合成了其他改变离子液体烷基链的吸附剂，并通过离线固相萃取评估了磺胺类药物的萃取。随着烷基链长度的增加，提取的磺胺类药物的量减少，这可能是由于极性降低导致静电相互作用减弱，以及存在六氟磷酸根阴离子增加材料疏水性所致。使用 1-丁基-3-甲基咪唑六氟磷酸盐作为选择性离子液体吸附剂，通过在线固相萃取与液相色谱和电喷雾电离飞行时间质谱联用，实现了牛奶中磺胺类药物的分离和预浓缩。该方法的定量限为 5-7、5μg/mL，萃取回收率在 74%至 93%之间，内标和日间分别在 1.5-12.5%和 2.3-13.1%之间。
