Qin Weiwei,He Yang,Xiao Jinyi,Liang Shengwang,Wang Shumei,Li Paul C. H.,Sun Yue
Liquid–liquid solvent extraction is frequently used in the purification of active ingredients from plants, and repeated extraction by different solvents with different polarity is often demanded to improve purity. According to this demand, two kinds of laminar flow extraction were designed on the microfluidic chip, i.e. a three-phase laminar chip and a successive laminar flow chip, and compared with a current two-phase chip. P. ginseng was used as a model plant to demonstrate extraction performance, and ether and n -butanol were used as the degrease solvent and extraction solvent, respectively. The results demonstrated that the extraction efficiency of a successive laminar flow chip is higher than that of a three-phase laminar flow chip, and that of both chips are higher than that of a two-phase chip. The chip method provided a new way to extract active ingredients from plants, which should be easily automated and integrated with other units to develop a complex system for sample preparation and ingredient detection.
Yingzhi Hu,Huaidong Peng,Youshao Yan,Shuyu Guan,Shumei Wang,Paul C.H. Li,Yue Sun
The design, construction and testing for integration of liquid-liquid extraction (EX) and capillary electrophoretic (CE) separation on one glass microchip was reported. In this EX-CE chip, a 1.5 cm-long and 200 μm-wide EX channel was used for extraction based on the two-phase laminar flow , followed by a single-cross CE unit for on-line analysis without any auxiliary devices. One side of the EX channel surface for the organic solvent phase was selectively modified to be hydrophobic while the surface of the other side for the aqueous phase remained hydrophilic, and the extraction product reservoir is also used as the sample reservoir for the subsequent chip separation in the CE channel. With the surface-directed liquid flow behavior and liquid level adjustment in various reservoirs of the EX-CE chip, no disturbance occurred between the extraction (EX) and capillary electrophoretic (CE) units. A small heating block was placed under the chip to accelerate solvent evaporation after liquid-liquid extraction. Sanguinarine (SAN), a plant alkaloid , was used as a model analyte to evaluate the performance of the EX-CE chip. The influences of organic solvent type and liquid flow speed on the extraction efficiency were investigated. Rhodamine 123 (Rh123) was used as an internal standard for quantification of Sanguinarine (SAN) in a physiological buffer (e.g. PBS) or blood samples. A good linearity in the concentration range of 0.05 μg mL −1 to 0.1 mg mL −1 for SAN in PBS was obtained, with the detection limit of 0.5 ng mL −1 . Good repeatibilities for migration times (RSD of SAN is 0.63%, Rh123 is 0.91%, n = 5) and peak area ratio of SAN to Rh123 (RSD is 1.3%, n = 5) were obtained. For blood sample analysis, only 20 μL of sample was needed, and the whole analysis was finished in 17 min. In addition to the advantages in fast analysis speed, minimum sample handling, potential automation, the reported method showed an on-line sample pre-concentration capability.
Wang Fei,Wang Hua-Lin,Qiu Yang,Chang Yu-Long,Long Yi-Tao
In this study, we performed micro-scale dynamic laminar flow extraction and site-specific in situ chloride concentration measurements. Surface-enhanced Raman spectroscopy was utilized to investigate the diffusion process of chloride ions from an oil phase to a water phase under laminar flow. In contrast to common logic, we used SERS intensity gradients of Rhodamine 6G to quantitatively calculate the concentration of chloride ions at specific positions on a microfluidic chip. By varying the fluid flow rates, we achieved different extraction times and therefore different chloride concentrations at specific positions along the microchannel. SERS spectra from the water phase were recorded at these different positions and the spatial distribution of the SERS signals was used to map the degree of nanoparticle aggregation. The concentration of chloride ions in the channel could therefore be obtained. We conclude that this method can be used to explore the extraction behaviour and efficiency of some ions or molecules that enhance the SERS intensity in water or oil by inducing nanoparticle aggregation.
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