| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1165904 | Analytica Chimica Acta | 2012 | 9 Pages |
Underground fluids are important natural sources of drinking water, geothermal energy, and oil-based fuels. To facilitate the surveying of such underground fluids, a novel microchannel extraction device was investigated for in-line continuous analysis and flow injection analysis of sulfide levels in water and in oil. Of the four designs investigated, the honeycomb-patterned microchannel extraction (HMCE) device was found to offer the most effective liquid–liquid extraction. In the HMCE device, a thin silicone membrane was sandwiched between two polydimethylsiloxane plates in which honeycomb-patterned microchannels had been fabricated. The identical patterns on the two plates were accurately aligned. The extracted sulfide was detected by quenching monitoring of fluorescein mercuric acetate (FMA). The sulfide extraction efficiencies from water and oil samples of the HMCE device and of three other designs (two annular and one rectangular channel) were examined theoretically and experimentally. The best performance was obtained with the HMCE device because of its thin sample layer (small diffusion distance) and large interface area. Quantitative extraction from both water and oil could be obtained using the HMCE device. The estimated limit of detection for continuous monitoring was 0.05 μM, and sulfide concentrations in the range of 0.15–10 μM could be determined when the acceptor was 5 μM FMA alkaline solution. The method was applied to natural water analysis using flow injection mode, and the data agreed with those obtained using headspace gas chromatography-flame photometric detection. The analysis of hydrogen sulfide levels in prepared oil samples was also performed. The proposed device is expected to be used for real time survey of oil wells and groundwater wells.
Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► We have developed a membrane-based microchannel extraction (HMCE) device. ► Extraction efficiency was examined theoretically and experimentally for this device. ► Quantitative extraction can be performed with the HMCE device while partial extraction with other conventional membrane-based devices. ► The HMCE device was applied for the measurement of free sulfide or hydrogen sulfide contained in water and oil samples. ► The presented device is expected to be used for survey of underground fluid such as groundwater and oil in future.
