Department of Analytical Chemistry, Faculty of Chemistry, c/Prof. García González s/n, 41012, Seville, Spain.
Department of Analytical Chemistry, Universitat Autónoma de Barcelona, 08193 Bellaterra, Barcelona, Spain.
J Chromatogr A. 2018 Jun 29;1556:29-36. doi: 10.1016/j.chroma.2018.04.051. Epub 2018 Apr 30.
A new geometry for a versatile microfluidic-chip device based liquid phase microextraction was developed in order to enhance the preconcentration in microfluidic chips and also to enable double-flow and stopped-flow working modes. The microchip device was combined with a HPLC procedure for the simultaneous determination of two different families as model analytes, which were parabens and non-steroidal anti-inflammatories (NSAIDs): Ethyl 4-hydroxybenzoate (Et-P), Propyl 4-hydroxybenzoate (Pr-P), Butyl 4-hydroxybenzoate (Bu-P), IsoButyl 4-hydroxybenzoate (iBu-P), salycilic acid (SAC), ketoprofen (KET), naproxen (NAX), diclofenac (DIC) and ibuprofen (IBU) in urine samples. The new miniaturized microchip proposed in this work allows not only the possibility of working in double-flow conditions, but also under stagnant conditions (stopped-flow) (SF-μLPME). The sample (pH 1.5) was delivered to the SF-μLPME at 20 μL min while keeping the acceptor phase (pH 11.75) under stagnant conditions during 20 min. The highest enrichment factors (between 16 and 47) were obtained under stopped-flow conditions at 20 μL min (sample flow rate) after 20 min extraction; whereas the extraction efficiencies were within the range of 27-81% for all compounds. The procedure provided very low detection limits between 0.7 and 8.5 μg L with a sample volume consumption of 400 μL. Parabens and NSAIDs have successfully been extracted from urine samples with excellent clean up and recoveries over 90% for all compounds. In parallel, the new device was also tested under double flow conditions, obtaining good but lower enrichment factors (between 9 and 20) and higher extraction efficiencies (between 45 and 95) after 7 min extraction, consuming a volume sample of 140 μL. The versatile device offered very high extraction efficiencies and good enrichment factor for double flow and stopped-flow conditions, respectively. In addition, this new miniaturized SF-μLPME device significantly reduced costs compared to the existing analytical techniques for sample preparation since this microchip require few microliters of sample and reagents and it is reusable.
为了增强微流控芯片中的预浓缩效果，并实现双流和停流工作模式，开发了一种基于新几何形状的多功能微流控芯片装置，用于液相微萃取。该微芯片装置与 HPLC 程序结合，用于同时测定两种不同的模型分析物，即对羟基苯甲酸酯和非甾体抗炎药（NSAIDs）：对羟基苯甲酸乙酯（Et-P）、对羟基苯甲酸丙酯（Pr-P）、对羟基苯甲酸丁酯（Bu-P）、对羟基苯甲酸异丁酯（iBu-P）、水杨酸（SAC）、酮洛芬（KET）、萘普生（NAX）、双氯芬酸（DIC）和布洛芬（IBU）。这项工作中提出的新型微型化微芯片不仅可以在双流条件下工作，还可以在停滞条件（停流）（SF-μLPME）下工作。在 20 分钟内，将样品（pH 1.5）以 20 μL/min 的速度输送到 SF-μLPME，而在 20 分钟内保持接受相（pH 11.75）处于停滞状态。在 20 分钟的提取后，在 20 μL/min（样品流速）的停流条件下，可获得最高的富集因子（16-47 之间）；而所有化合物的萃取效率均在 27-81%范围内。该方法在样品体积消耗为 400 μL 的情况下，提供了非常低的检测限，范围在 0.7 到 8.5 μg/L 之间。对羟基苯甲酸酯和 NSAIDs 已成功从尿液样品中提取出来，所有化合物的净化效果都非常好，回收率超过 90%。同时，在双流条件下也对新装置进行了测试，在 7 分钟的提取后，获得了较好但较低的富集因子（9-20 之间）和较高的萃取效率（45-95%），样品体积消耗为 140 μL。该多功能装置在双流和停流条件下均提供了非常高的萃取效率和良好的富集因子。此外，与现有的样品制备分析技术相比，这种新型的微型化 SF-μLPME 装置大大降低了成本，因为这种微芯片只需要几微升的样品和试剂，并且可以重复使用。
