A double-stage Lab-In-Syringe automated extraction procedure coupled online to HPLC for the determination of four sulfonamides in urine has been developed. Our method is based on homogeneous liquid-liquid extraction at pH 3 using water-miscible acetonitrile with induction of phase separation by the addition of a saturated solution of kosmotropic salts MgSO₄ and NaCl. The procedure allowed extraction of the moderately polar model analytes and the use of a solvent that is compatible with the used separation technique. The automated sample preparation system based on the stirring-assisted Lab-In-Syringe approach was coupled on-line with HPLC-UV for the subsequent separation of the sulfonamide antibiotics. To improve both preconcentration factor and extract cleanup, the analytes were trapped at pH 10 in an anion-exchange resin cartridge integrated into the HPLC injection loop thus achieving a double-stage sample clean-up. Analytes were eluted using an acidic HPLC mobile phase in gradient elution mode. Running the analytes separation and the two-step preparation of the following sample in parallel reduced the total time of analysis to mere 13.5 min. Limits of detection ranged from 5.0 to 7.5 μg/L with linear working ranges of 50–5000 μg/L (r² > 0.9997) and RSD ≤ 5% (n = 6) at a concentration level of 50 μg/L. Average recovery values were 102.7 ± 7.4% after spiking of urine with sulfonamides at concentrations of 2.5 and 5 mg/L followed by 5 times dilution. To the best of our knowledge, the use of Lab-In-Syringe for the automation of coupled homogeneous liquid-liquid extraction and SPE for preparation of the complex matrices suitable for separation techniques is here presented for the first time.

已开发出一种在线在线与HPLC联用的双阶段Lab-In-Singlee自动萃取程序，用于测定尿液中的四种磺酰胺。我们的方法基于在pH 3下使用与水混溶的乙腈进行均匀的液-液萃取，并通过添加一种均质盐MgSO ₄饱和溶液来诱导相分离。和氯化钠。该程序允许提取中等极性的模型分析物，并使用与所用分离技术兼容的溶剂。基于搅拌辅助实验室注射方法的自动样品制备系统与HPLC-UV在线耦合，用于随后分离磺酰胺类抗生素。为了同时提高预浓缩因子和提取物净化效果，将分析物在pH值为10的条件下捕获在集成到HPLC进样环中的阴离子交换树脂柱中，从而实现了两阶段的样品净化。使用酸性HPLC流动相以梯度洗脱模式洗脱分析物。并行进行分析物分离和两步制备以下样品，将总分析时间缩短至仅13.5分钟。检测限范围从5.0到7。²  > 0.9997），且浓度水平为50μg/ L时RSD≤5％（n = 6）。用浓度为2.5和5 mg / L的磺酰胺加尿液稀释5倍后，尿液的平均回收率为102.7±7.4％。据我们所知，这里首次介绍了使用实验室中的注射器自动进行均相液-液萃取和SPE制备适用于分离技术的复杂基质。