Institute of Chemistry, Federal University of Goiás, Goiânia, GO 59078-970, Brazil.
CENPES, PETROBRAS, Rio de Janeiro, RJ 21941-915, Brazil.
J Am Soc Mass Spectrom. 2022 Aug 3;33(8):1510-1517. doi: 10.1021/jasms.2c00107. Epub 2022 Jul 22.
Naphthenic acids comprise one of the most toxic compounds of the produced water released from offshore oil platforms. Therefore, developing and applying faster, simpler, and more efficient analytical methods for analyzing naphthenic acids are urgently needed. Electromembrane extraction (EME) uses the electrokinetic migration of target ions through a porous membrane. Herein, the EME method was applied to extract naphthenic acids from produced water. The EME method was optimized, and the optimal conditions encompassed decanol as the organic solvent, the sample with pH 10.0, 5 min of extraction at 200 V, and the ratio 4:1 (borate buffer/matrix, v/v). Electrochemical impedance spectroscopy confirmed charged species' migration from produced water through the EME. Subsequently, all extracts were analyzed by ultra-high-resolution mass spectrometry. The EME efficiency was assessed by comparing the extraction results to the liquid-liquid extraction (LLE) method results. Analytical results showed good linearity for both solvent and matrix curves ( > 0.98). Low detection limits ranged from 0.10 to 0.13 μg mL and quantification limits from 0.36 to 0.45 μg mL. Precision and accuracy values ranged from -13.3% to 16.5%. These values fit the proposed method, demonstrating that the EME was more efficient than LLE in naphthenic acid extraction. The EME method preferably extracted aromatic compounds with double-bond equivalence from 6 to 8. The EME coupled with ultra-high-resolution mass spectrometry was demonstrated as a promising analytical approach to naphthenic acid extraction as an efficient and more environmentally friendly alternative to conventional extraction methods.
环烷酸是从海上石油平台排放的采出水中毒性最大的化合物之一。因此，开发和应用更快、更简单、更有效的分析方法来分析环烷酸迫在眉睫。电渗析萃取（EME）利用目标离子通过多孔膜的电动迁移。在此，将 EME 方法应用于从采出水中提取环烷酸。对 EME 方法进行了优化，最佳条件包括癸醇作为有机溶剂、pH 值为 10.0 的样品、在 200 V 下萃取 5 分钟，以及硼酸盐缓冲液/基质比为 4:1（v/v）。电化学阻抗谱证实了带电物质从采出水通过 EME 的迁移。随后，所有提取物均通过超高效分辨率质谱进行分析。通过将萃取结果与液液萃取（LLE）方法的结果进行比较来评估 EME 效率。分析结果表明溶剂和基质曲线的线性良好（>0.98）。低检测限范围为 0.10 至 0.13μg mL，定量限范围为 0.36 至 0.45μg mL。精密度和准确度值范围为-13.3%至 16.5%。这些值符合所提出的方法，表明 EME 在环烷酸萃取方面比 LLE 更有效。EME 方法优选萃取具有 6 至 8 个双键等价物的芳香族化合物。将 EME 与超高效分辨率质谱相结合，被证明是一种很有前途的分析方法，可用于环烷酸的提取，是对传统提取方法的有效且更环保的替代方法。
