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Yang Z, Zhang J, Zhao J, Zhou W, Cheng Y, Xu Z, Wei P, Wang Z, Liang H, Li C. A high-sensitivity lab-on-a-chip analyzer for online monitoring of nitrite and nitrate in seawater based on liquid waveguide capillary cells. LAB ON A CHIP 2024; 24:3528-3535. [PMID: 38940766 DOI: 10.1039/d4lc00248b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/29/2024]
Abstract
Optical detection is an indispensable part of microfluidic systems for nutrient determination in seawater. Coupling total internal reflection capillaries with microfluidic chips is a practical alternative to increase the optical path length for high-sensitivity and a low detection limit in colorimetric assays, which has not been applied in microfluidic devices for seawater nutrients. Here, we present an online microfluidic system which integrated a total internal reflection capillary made of Teflon AF 2400 for the high-sensitivity detection of nitrite and nitrate in seawater. The off-chip capillary lengthens the optical path without changing the internal flow path of the microfluidic chip, enhancing the sensitivity, reducing the detection limit and widening the dynamic range of the system, which significantly improves the performance of the microfluidic system based on wet-chemistry. The detection limit for nitrite is 0.0150 μM using an external 20 cm capillary and 0.0936 μM using an internal 5 cm absorption cell, providing an over 6-fold improvement. Laboratory analysis of surface seawater samples collected from the South China Sea with this system and a one-month online deployment of an autonomous analyzer developed based on this system at a station revealed correlations between the nitrite and nitrate with tide, salinity and chlorophyll over slight variations and narrow ranges, demonstrating the high-sensitivity of this method.
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Affiliation(s)
- Zeming Yang
- State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 511458, P.R. China.
- Key Laboratory of Marine Environmental Survey Technology and Application, Ministry of Natural Resources, Guangzhou, 510310, P.R. China
| | - Junxiao Zhang
- Key Laboratory of Marine Environmental Survey Technology and Application, Ministry of Natural Resources, Guangzhou, 510310, P.R. China
- South China Sea Marine Survey Center, Ministry of Natural Resources, Guangzhou, 510310, P.R. China
| | - Jincheng Zhao
- State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 511458, P.R. China.
- University of Chinese Academy of Sciences, Beijing, 100049, P.R. China
| | - Wen Zhou
- State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 511458, P.R. China.
| | - Yuanyue Cheng
- State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 511458, P.R. China.
| | - Zhantang Xu
- State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 511458, P.R. China.
| | - Panpan Wei
- State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 511458, P.R. China.
- University of Chinese Academy of Sciences, Beijing, 100049, P.R. China
| | - Zihui Wang
- State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 511458, P.R. China.
- University of Chinese Academy of Sciences, Beijing, 100049, P.R. China
| | - Haorui Liang
- South China Sea Marine Survey Center, Ministry of Natural Resources, Guangzhou, 510310, P.R. China
| | - Cai Li
- State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 511458, P.R. China.
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2
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Motahari S, Morgan S, Hendricks A, Sonnichsen C, Sieben V. Continuous Flow with Reagent Injection on an Inlaid Microfluidic Platform Applied to Nitrite Determination. MICROMACHINES 2024; 15:519. [PMID: 38675330 PMCID: PMC11052183 DOI: 10.3390/mi15040519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Revised: 03/25/2024] [Accepted: 04/09/2024] [Indexed: 04/28/2024]
Abstract
A continuous flow with reagent injection method on a novel inlaid microfluidic platform for nitrite determination has been successfully developed. The significance of the high-frequency monitoring of nutrient fluctuations in marine environments is crucial for understanding our impacts on the ecosystem. Many in-situ systems face limitations in high-frequency data collection and have restricted deployment times due to high reagent consumption. The proposed microfluidic device employs automatic colorimetric absorbance spectrophotometry, using the Griess assay for nitrite determination, with minimal reagent usage. The sensor incorporates 10 solenoid valves, four syringes, two LEDs, four photodiodes, and an inlaid microfluidic technique to facilitate optical measurements of fluid volumes. In this flow system, Taylor-Aris dispersion was simulated for different injection volumes at a constant flow rate, and the results have been experimentally confirmed using red food dye injection into a carrier stream. A series of tests were conducted to determine a suitable injection frequency for the reagent. Following the initial system characterization, seven different standard concentrations ranging from 0.125 to 10 µM nitrite were run through the microfluidic device to acquire a calibration curve. Three different calibrations were performed to optimize plug length, with reagent injection volumes of 4, 20, and 50 µL. A straightforward signal processing method was implemented to mitigate the Schlieren effect caused by differences in refractive indexes between the reagent and standards. The results demonstrate that a sampling frequency of at least 10 samples per hour is achievable using this system. The obtained attenuation coefficients exhibited good agreement with the literature, while the reagent consumption was significantly reduced. The limit of detection for a 20 µL injection volume was determined to be 94 nM from the sample intake, and the limit of quantification was 312 nM. Going forward, the demonstrated system will be packaged in a submersible enclosure to facilitate in-situ colorimetric measurements in marine environments.
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Affiliation(s)
- Shahrooz Motahari
- Department of Electrical & Computer Engineering, Dalhousie University, 1360 Barrington Street, Halifax, NS B3H 4R2, Canada; (S.M.); (A.H.); (C.S.)
| | - Sean Morgan
- Department of Oceanography, Dalhousie University, 1355 Oxford Street, Halifax, NS B3H 4R2, Canada;
| | - Andre Hendricks
- Department of Electrical & Computer Engineering, Dalhousie University, 1360 Barrington Street, Halifax, NS B3H 4R2, Canada; (S.M.); (A.H.); (C.S.)
| | - Colin Sonnichsen
- Department of Electrical & Computer Engineering, Dalhousie University, 1360 Barrington Street, Halifax, NS B3H 4R2, Canada; (S.M.); (A.H.); (C.S.)
| | - Vincent Sieben
- Department of Electrical & Computer Engineering, Dalhousie University, 1360 Barrington Street, Halifax, NS B3H 4R2, Canada; (S.M.); (A.H.); (C.S.)
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3
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Morgan S, Luy E, Furlong A, Sieben V. A submersible phosphate analyzer for marine environments based on inlaid microfluidics. ANALYTICAL METHODS : ADVANCING METHODS AND APPLICATIONS 2021; 14:22-33. [PMID: 34874983 DOI: 10.1039/d1ay01876k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
In situ sensors are needed to further our understanding of phosphate flux dynamics in marine environments during short term events such as tidal cycles, algae blooms and runoff periods. Here, we present a fully automated in situ phosphate analyzer based on an inlaid microfluidic absorbance cell technology. The microfluidic device employs colorimetric absorbance spectrophotometry, using the phosphomolybdenum blue (PMB) assay modified by the addition of polyvinylpyrrolidone (PVP), to measure phosphate concentrations in seawater. Bench top calibrations were performed with both copper(II) sulfate dye and the PMB assay, as well as temperature sensitivity studies to characterize the sensor's performance in a range of conditions. It achieves a limit of detection of 15.2 nM, a limit of quantification of 50.8 nM, and a high in situ precision with a relative standard deviation of less than 1.5% across three consecutive measurements. Two consecutive field deployments are conducted as assessments for its intended in situ applications. The sensor is first deployed from a pier at a depth of 6 m, with simultaneous bottle samples taken to perform cross-validation. It is next deployed on the Stella Maris testbed, a multi-sensor seabed platform (MSSP), 100 m offshore and 9 m deep in the inlet to the Bedford Basin in Nova Scotia, Canada. Over 300 successful phosphate measurements were acquired, showing the influence of the tidal cycle, and confirming the sensor's viability in observing nutrient flux dynamics with nanomolar variations.
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Affiliation(s)
- Sean Morgan
- Department of Electrical and Computer Engineering, Dalhousie University, 1360 Barrington Street, Halifax, Nova Scotia, B3H 4R2, Canada.
| | - Edward Luy
- Dartmouth Ocean Technologies Inc., 25 Parker Street, Suite 21401, Dartmouth, Nova Scotia, B2Y 4TS, Canada
| | - Arnold Furlong
- Dartmouth Ocean Technologies Inc., 25 Parker Street, Suite 21401, Dartmouth, Nova Scotia, B2Y 4TS, Canada
| | - Vincent Sieben
- Department of Electrical and Computer Engineering, Dalhousie University, 1360 Barrington Street, Halifax, Nova Scotia, B3H 4R2, Canada.
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4
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Fukuba T, Fujii T. Lab-on-a-chip technology for in situ combined observations in oceanography. LAB ON A CHIP 2021; 21:55-74. [PMID: 33300537 DOI: 10.1039/d0lc00871k] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The oceans sustain the global environment and diverse ecosystems through a variety of biogeochemical processes and their complex interactions. In order to understand the dynamism of the local or global marine environments, multimodal combined observations must be carried out in situ. On the other hand, instrumentation of in situ measurement techniques enabling biological and/or biochemical combined observations is challenging in aquatic environments, including the ocean, because biochemical flow analyses require a more complex configuration than physicochemical electrode sensors. Despite this technical hurdle, in situ analyzers have been developed to measure the concentrations of seawater contents such as nutrients, trace metals, and biological components. These technologies have been used for cutting-edge ocean observations to elucidate the biogeochemical properties of water mass with a high spatiotemporal resolution. In this context, the contribution of lab-on-a-chip (LoC) technology toward the miniaturization and functional integration of in situ analyzers has been gaining momentum. Due to their mountability, in situ LoC technologies provide ideal instrumentation for underwater analyzers, especially for miniaturized underwater observation platforms. Consequently, the appropriate combination of reliable LoC and underwater technologies is essential to realize practical in situ LoC analyzers suitable for underwater environments, including the deep sea. Moreover, the development of fundamental LoC technologies for underwater analyzers, which operate stably in extreme environments, should also contribute to in situ measurements for public or industrial purposes in harsh environments as well as the exploration of the extraterrestrial frontier.
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Affiliation(s)
- Tatsuhiro Fukuba
- Institute for Marine-Earth Exploration and Engineering, Japan Agency for Marine-Earth Science and Technology, Natsushima-cho 2-15, Yokosuka, Kanagawa 237-0061, Japan.
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5
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Morgan SC, Hendricks AD, Seto ML, Sieben VJ. A Magnetically Tunable Check Valve Applied to a Lab-on-Chip Nitrite Sensor. SENSORS (BASEL, SWITZERLAND) 2019; 19:E4619. [PMID: 31652900 PMCID: PMC6864443 DOI: 10.3390/s19214619] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Revised: 10/17/2019] [Accepted: 10/21/2019] [Indexed: 12/16/2022]
Abstract
Presented here is the fabrication and characterization of a tunable microfluidic check valve for use in marine nutrient sensing. The ball-style valve makes use of a rare-earth permanent magnet, which exerts a pulling force to ensure it remains passively sealed until the prescribed cracking pressure is met. By adjusting the position of the magnet, the cracking pressure is shown to be customizable to meet design requirements. Further applicability is shown by integrating the valve into a poly(methyl methacrylate) (PMMA) lab-on-chip device with an integrated optical absorbance cell for nitrite detection in seawater. Micro-milling is used to manufacture both the valve and the micro-channel structures. The valve is characterized up to a flow rate of 14 mL min-1 and exhibits low leakage rates at high back pressures (<2 µL min-1 at ~350 kPa). It is low cost, requires no power, and is easily implemented on microfluidic platforms.
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Affiliation(s)
- Sean C Morgan
- Department of Electrical and Computer Engineering, Dalhousie University, 1360 Barrington Street, Halifax, NS B3H 4R2, Canada.
| | - Andre D Hendricks
- Department of Electrical and Computer Engineering, Dalhousie University, 1360 Barrington Street, Halifax, NS B3H 4R2, Canada.
| | - Mae L Seto
- Department of Electrical and Computer Engineering, Dalhousie University, 1360 Barrington Street, Halifax, NS B3H 4R2, Canada.
| | - Vincent J Sieben
- Department of Electrical and Computer Engineering, Dalhousie University, 1360 Barrington Street, Halifax, NS B3H 4R2, Canada.
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6
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Nightingale AM, Hassan SU, Warren BM, Makris K, Evans GWH, Papadopoulou E, Coleman S, Niu X. A Droplet Microfluidic-Based Sensor for Simultaneous in Situ Monitoring of Nitrate and Nitrite in Natural Waters. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:9677-9685. [PMID: 31352782 DOI: 10.1021/acs.est.9b01032] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Microfluidic-based chemical sensors take laboratory analytical protocols and miniaturize them into field-deployable systems for in situ monitoring of water chemistry. Here, we present a prototype nitrate/nitrite sensor based on droplet microfluidics that in contrast to standard (continuous phase) microfluidic sensors, treats water samples as discrete droplets contained within a flow of oil. The new sensor device can quantify the concentrations of nitrate and nitrite within each droplet and provides high measurement frequency and low fluid consumption. Reagent consumption is at a rate of 2.8 mL/day when measuring every ten seconds, orders of magnitude more efficient than those of the current state-of-the-art sensors. The sensor's capabilities were demonstrated during a three-week deployment in a tidal river. The accurate and high frequency data (6% error relative to spot samples, measuring at 0.1 Hz) elucidated the influence of tidal variation, rain events, diurnal effects, and anthropogenic input on concentrations at the deployment site. This droplet microfluidic-based sensor is suitable for a wide range of applications such as monitoring of rivers, lakes, coastal waters, and industrial effluents.
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Affiliation(s)
- Adrian M Nightingale
- Mechanical Engineering, Faculty of Engineering and Physical Sciences , University of Southampton , Southampton , SO17 1BJ , United Kingdom
| | - Sammer-Ul Hassan
- Mechanical Engineering, Faculty of Engineering and Physical Sciences , University of Southampton , Southampton , SO17 1BJ , United Kingdom
| | - Brett M Warren
- SouthWestSensor Ltd , Enterprise House, Ocean Village , Southampton , SO14 3XB , United Kingdom
| | - Kyriacos Makris
- SouthWestSensor Ltd , Enterprise House, Ocean Village , Southampton , SO14 3XB , United Kingdom
| | - Gareth W H Evans
- Mechanical Engineering, Faculty of Engineering and Physical Sciences , University of Southampton , Southampton , SO17 1BJ , United Kingdom
| | - Evanthia Papadopoulou
- SouthWestSensor Ltd , Enterprise House, Ocean Village , Southampton , SO14 3XB , United Kingdom
| | - Sharon Coleman
- Mechanical Engineering, Faculty of Engineering and Physical Sciences , University of Southampton , Southampton , SO17 1BJ , United Kingdom
- SouthWestSensor Ltd , Enterprise House, Ocean Village , Southampton , SO14 3XB , United Kingdom
| | - Xize Niu
- Mechanical Engineering, Faculty of Engineering and Physical Sciences , University of Southampton , Southampton , SO17 1BJ , United Kingdom
- SouthWestSensor Ltd , Enterprise House, Ocean Village , Southampton , SO14 3XB , United Kingdom
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7
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Tweedie M, Sun D, Ward B, Maguire PD. Long-term hydrolytically stable bond formation for future membrane-based deep ocean microfluidic chemical sensors. LAB ON A CHIP 2019; 19:1287-1295. [PMID: 30848276 DOI: 10.1039/c9lc00123a] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Future ocean profiling of dissolved inorganic carbon and other analytes will require miniaturised chemical analysis systems based on sealed gas membranes between two fluid channels. However, for long-term deployment in the deep ocean at high pressure, the ability to seal incompatible materials represents an immense challenge. We demonstrate proof of principle high strength bond sealing. We show that polydimethylsiloxane (PDMS) is a preferred membrane material for rapid CO2 transfer, without ion leakage, and report long-term stable bonding of thin PDMS membrane films to inert thermoplastic poly(methyl methacrylate) (PMMA) patterned manifolds. Device channels were filled with 0.01 M NaOH and subjected to repeated tape pull and pressure - flow tests without failure for up to six weeks. Bond formation utilised a thin coating of the aminosilane bis-[3-trimethoxysilylpropyl]amine (BTMSPA) conformally coated onto PMMA channels and surfaces and cured. All surfaces were subsequently plasma treated and devices subject to thermocompressive bond annealing. Successful chemically resistant bonding of membrane materials to thermoplastics opens the possibility of remote environmental chemical analysis and offers a route to float-based depth profiling of dissolved inorganic carbon in the oceans.
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Affiliation(s)
- M Tweedie
- NIBEC, Ulster University, Belfast, BT37 0QB, Northern Ireland, UK.
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8
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Hassan SU, Nightingale AM, Niu X. Continuous measurement of enzymatic kinetics in droplet flow for point-of-care monitoring. Analyst 2018; 141:3266-73. [PMID: 27007645 DOI: 10.1039/c6an00620e] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Droplet microfluidics is ideally suited to continuous biochemical analysis, requiring low sample volumes and offering high temporal resolution. Many biochemical assays are based on enzymatic reactions, the kinetics of which can be obtained by probing droplets at multiple points over time. Here we present a miniaturised multi-detector flow cell to analyse enzyme kinetics in droplets, with an example application of continuous glucose measurement. Reaction rates and Michaelis-Menten kinetics can be quantified for each individual droplet and unknown glucose concentrations can be accurately determined (errors <5%). Droplets can be probed continuously giving short sample-to-result time (∼30 s) measurement. In contrast to previous reports of multipoint droplet measurement (all of which used bulky microscope-based setups) the flow cell presented here has a small footprint and uses low-powered, low-cost components, making it ideally suited for use in field-deployable devices.
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Affiliation(s)
- Sammer-Ul Hassan
- Faculty of Engineering and the Environment, University of Southampton, Southampton, SO17 1BJ, UK.
| | - Adrian M Nightingale
- Faculty of Engineering and the Environment, University of Southampton, Southampton, SO17 1BJ, UK.
| | - Xize Niu
- Faculty of Engineering and the Environment, University of Southampton, Southampton, SO17 1BJ, UK. and Institute for Life Sciences, University of Southampton, Southampton, SO17 1BJ, UK
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9
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Kanoatov M, Mehrabanfar S, Krylov SN. Systematic Approach to Optimization of Experimental Conditions in Nonequilibrium Capillary Electrophoresis of Equilibrium Mixtures. Anal Chem 2016; 88:9300-8. [DOI: 10.1021/acs.analchem.6b02882] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Mirzo Kanoatov
- Department of Chemistry and
Centre for Research on Biomolecular Interactions, York University, Toronto, Ontario M3J 1P3, Canada
| | - Sina Mehrabanfar
- Department of Chemistry and
Centre for Research on Biomolecular Interactions, York University, Toronto, Ontario M3J 1P3, Canada
| | - Sergey N. Krylov
- Department of Chemistry and
Centre for Research on Biomolecular Interactions, York University, Toronto, Ontario M3J 1P3, Canada
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10
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Sieben VJ, Tharanivasan AK, Ratulowski J, Mostowfi F. Asphaltenes yield curve measurements on a microfluidic platform. LAB ON A CHIP 2015; 15:4062-4074. [PMID: 26333290 DOI: 10.1039/c5lc00547g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We describe a microfluidic apparatus and method for performing asphaltene yield measurements on crude oil samples. Optical spectroscopy measurements are combined with a microfluidic fluid handling platform to create an automated microfluidic apparatus to measure the asphaltene yield. The microfluidic measurements show good agreement with conventional wet chemistry measurements as well as available models. The initial absorbance of the oil is measured, and asphaltenes are removed from the oil by the gradual addition of n-alkane, which leads to flocculation and subsequent filtration. The absorbance of the de-asphalted oil (maltenes) is then measured and the initial asphaltene content is determined by the change in absorbance. The solubility of asphaltene is evaluated by varying the titrant-to-oil ratio (e.g., n-heptane-oil), which induces no, partial, or full precipitation of asphaltenes depending on the chosen ratio. The absorbance of the filtrate is measured and normalized to the maximum content to determine the fractional precipitation at each ratio. Traditionally, a yield curve comprised of 20 such ratios would require weeks to months to generate, while consuming over 6 L of solvent and more than 100 g of crude oil sample. Using the microfluidic approach described here, the same measurement can be performed in 1 day, with 0.5 L of solvent and 10 g of crude oil sample. The substantial reduction in time and consumables will enable more frequent asphaltene yield measurements and reduce its environmental impact significantly.
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Affiliation(s)
- Vincent J Sieben
- Schlumberger Canada Limited, DBR Technology Center, 9450 17th Avenue, Edmonton, Alberta T6N 1M9, Canada.
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11
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Yücel M, Beaton AD, Dengler M, Mowlem MC, Sohl F, Sommer S. Nitrate and Nitrite Variability at the Seafloor of an Oxygen Minimum Zone Revealed by a Novel Microfluidic In-Situ Chemical Sensor. PLoS One 2015; 10:e0132785. [PMID: 26161958 PMCID: PMC4498834 DOI: 10.1371/journal.pone.0132785] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Accepted: 06/19/2015] [Indexed: 11/19/2022] Open
Abstract
Microfluidics, or lab-on-a-chip (LOC) is a promising technology that allows the development of miniaturized chemical sensors. In contrast to the surging interest in biomedical sciences, the utilization of LOC sensors in aquatic sciences is still in infancy but a wider use of such sensors could mitigate the undersampling problem of ocean biogeochemical processes. Here we describe the first underwater test of a novel LOC sensor to obtain in situ calibrated time-series (up to 40 h) of nitrate+nitrite (ΣNOx) and nitrite on the seafloor of the Mauritanian oxygen minimum zone, offshore Western Africa. Initial tests showed that the sensor successfully reproduced water column (160 m) nutrient profiles. Lander deployments at 50, 100 and 170 m depth indicated that the biogeochemical variability was high over the Mauritanian shelf: The 50 m site had the lowest ΣNOx concentration, with 15.2 to 23.4 μM (median=18.3 μM); while at the 100 site ΣNOx varied between 21.0 and 30.1 μM over 40 hours (median = 25.1μM). The 170 m site had the highest median ΣNOx level (25.8 μM) with less variability (22.8 to 27.7 μM). At the 50 m site, nitrite concentration decreased fivefold from 1 to 0.2 μM in just 30 hours accompanied by decreasing oxygen and increasing nitrate concentrations. Taken together with the time series of oxygen, temperature, pressure and current velocities, we propose that the episodic intrusion of deeper waters via cross-shelf transport leads to intrusion of nitrate-rich, but oxygen-poor waters to shallower locations, with consequences for benthic nitrogen cycling. This first validation of an LOC sensor at elevated water depths revealed that when deployed for longer periods and as a part of a sensor network, LOC technology has the potential to contribute to the understanding of the benthic biogeochemical dynamics.
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Affiliation(s)
- Mustafa Yücel
- GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany
- Middle East Technical University (METU), Institute of Marine Sciences, Erdemli, Mersin, Turkey
- * E-mail:
| | - Alexander D. Beaton
- National Oceanography Centre Southampton, Ocean Technology and Engineering Group, Southampton, United Kingdom
| | - Marcus Dengler
- GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany
| | - Matthew C. Mowlem
- National Oceanography Centre Southampton, Ocean Technology and Engineering Group, Southampton, United Kingdom
| | - Frank Sohl
- DLR German Aerospace Center, Institute for Planetary Science, Berlin, Germany
| | - Stefan Sommer
- GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany
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12
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Standard addition/absorption detection microfluidic system for salt error-free nitrite determination. Anal Chim Acta 2015; 886:114-22. [DOI: 10.1016/j.aca.2015.06.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Revised: 05/22/2015] [Accepted: 06/11/2015] [Indexed: 11/23/2022]
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13
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Rérolle VM, Floquet CF, Harris AJ, Mowlem MC, Bellerby RR, Achterberg EP. Development of a colorimetric microfluidic pH sensor for autonomous seawater measurements. Anal Chim Acta 2013; 786:124-31. [DOI: 10.1016/j.aca.2013.05.008] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2012] [Revised: 03/13/2013] [Accepted: 05/06/2013] [Indexed: 10/26/2022]
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14
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Pereira F, Niu X, deMello AJ. A nano LC-MALDI mass spectrometry droplet interface for the analysis of complex protein samples. PLoS One 2013; 8:e63087. [PMID: 23671657 PMCID: PMC3650041 DOI: 10.1371/journal.pone.0063087] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2012] [Accepted: 04/01/2013] [Indexed: 11/30/2022] Open
Abstract
The integration of matrix-assisted laser desorption ionization (MALDI) mass spectrometry with an upstream analytical separations (such as liquid chromatography and electrophoresis) has opened up new opportunities for the automated investigation of complex protein and peptide mixtures. The ability to efficiently analyze complex proteomic mixtures in this manner is primarily determined by the ability to preserve spatial discrimination of sample components as they leave the separation column. Current interfacing methods are problematic in this respect since minimum fraction volumes are limited to several microliters. Herein we show for the first time an LC-MALDI interface based on the formation, processing and destruction of a segmented flow. The interface consists of a droplet-generator to fractionate LC effluent into nL-volume droplets and a deposition probe that transfers the sample (and MALDI matrix) onto a conventional MALDI-MS target. The efficacy of the method is demonstrated through the analysis of Trypsin digests of both BSA and Cytochrome C, with a 50% enhancement in analytical performance when compared to conventional interface technology.
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Affiliation(s)
- Fiona Pereira
- Institute for Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zürich, Zurich, Switzerland
| | - Xize Niu
- Engineering and the Environment, and Institute for Life Sciences, University of Southampton, Highfield, Southampton, England
| | - Andrew J. deMello
- Institute for Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zürich, Zurich, Switzerland
- * E-mail:
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15
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Schneider MH, Sieben VJ, Kharrat AM, Mostowfi F. Measurement of asphaltenes using optical spectroscopy on a microfluidic platform. Anal Chem 2013; 85:5153-60. [PMID: 23614817 DOI: 10.1021/ac400495x] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We present a microfluidic apparatus and method for the measurement of asphaltene content in crude-oil samples. The measurement is based on an optical absorption technique, where it was established that asphaltene coloration correlated linearly with asphaltene weight content. The initial absorbance of the oil is measured, and asphaltenes are removed from the oil by the addition of n-alkane, leading to flocculation and subsequent filtration. The absorbance of the deasphalted oil (maltenes) is then measured, and the initial asphaltene content is revealed by the change in absorbance. The asphaltene optical densities correlated linearly with conventional weight measurement results (e.g., ASTM D6560) for 38 crude-oil samples from around the world. Sample measurement repeatability was shown to be within ±2% over several months. Other aspects influencing performance of the system were evaluated, including plug dispersion, flocculation kinetics, membrane degradation, and channel clogging. The microfluidic approach described here permits asphaltene content measurement in less than 30 min as opposed to days required with traditional gravimetric techniques. This many-fold reduction in measurement time will enable more frequent characterization of crude oil samples.
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Kovarik ML, Ornoff DM, Melvin AT, Dobes NC, Wang Y, Dickinson AJ, Gach PC, Shah PK, Allbritton NL. Micro total analysis systems: fundamental advances and applications in the laboratory, clinic, and field. Anal Chem 2013; 85:451-72. [PMID: 23140554 PMCID: PMC3546124 DOI: 10.1021/ac3031543] [Citation(s) in RCA: 170] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Michelle L. Kovarik
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Douglas M. Ornoff
- Department of Pharmacology, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Adam T. Melvin
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Nicholas C. Dobes
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Yuli Wang
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Alexandra J. Dickinson
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Philip C. Gach
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Pavak K. Shah
- Department of Biomedical Engineering, University of North Carolina, Chapel Hill, NC 27599 and North Carolina State University, Raleigh, NC 27695
| | - Nancy L. Allbritton
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599
- Department of Pharmacology, University of North Carolina, Chapel Hill, North Carolina 27599
- Department of Biomedical Engineering, University of North Carolina, Chapel Hill, NC 27599 and North Carolina State University, Raleigh, NC 27695
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Campos CDM, da Silva JAF. Applications of autonomous microfluidic systems in environmental monitoring. RSC Adv 2013. [DOI: 10.1039/c3ra41561a] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
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Beaton AD, Cardwell CL, Thomas RS, Sieben VJ, Legiret FE, Waugh EM, Statham PJ, Mowlem MC, Morgan H. Lab-on-chip measurement of nitrate and nitrite for in situ analysis of natural waters. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2012; 46:9548-9556. [PMID: 22835223 DOI: 10.1021/es300419u] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Microfluidic technology permits the miniaturization of chemical analytical methods that are traditionally undertaken using benchtop equipment in the laboratory environment. When applied to environmental monitoring, these "lab-on-chip" systems could allow high-performance chemical analysis methods to be performed in situ over distributed sensor networks with large numbers of measurement nodes. Here we present the first of a new generation of microfluidic chemical analysis systems with sufficient analytical performance and robustness for deployment in natural waters. The system detects nitrate and nitrite (up to 350 μM, 21.7 mg/L as NO(3)(-)) with a limit of detection (LOD) of 0.025 μM for nitrate (0.0016 mg/L as NO(3)(-)) and 0.02 μM for nitrite (0.00092 mg/L as NO(2)(-)). This performance is suitable for almost all natural waters (apart from the oligotrophic open ocean), and the device was deployed in an estuarine environment (Southampton Water) to monitor nitrate+nitrite concentrations in waters of varying salinity. The system was able to track changes in the nitrate-salinity relationship of estuarine waters due to increased river flow after a period of high rainfall. Laboratory characterization and deployment data are presented, demonstrating the ability of the system to acquire data with high temporal resolution.
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Abstract
This paper highlights the importance of the collection of data that is of suitable quality and of appropriate frequency and/or spatial intensity for the monitoring of aquatic systems. The advantages of automated techniques, such as flow analysis, in monitoring are emphasized, as is the selection of parameters that address the objectives of monitoring. The potential of nascent microfluidic and paper-based analytical techniques as tools for water quality monitoring is examined.
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Kim SJ, Yokokawa R, Lesher-Perez SC, Takayama S. Constant flow-driven microfluidic oscillator for different duty cycles. Anal Chem 2012; 84:1152-6. [PMID: 22206453 PMCID: PMC3264749 DOI: 10.1021/ac202866b] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
This paper presents microfluidic devices that autonomously convert two constant flow inputs into an alternating oscillatory flow output. We accomplish this hardware embedded self-control programming using normally closed membrane valves that have an inlet, an outlet, and a membrane-pressurization chamber connected to a third terminal. Adjustment of threshold opening pressures in these 3-terminal flow switching valves enabled adjustment of oscillation periods to between 57 and 360 s with duty cycles of 0.2-0.5. These values are in relatively good agreement with theoretical values, providing the way for rational design of an even wider range of different waveform oscillations. We also demonstrate the ability to use these oscillators to perform temporally patterned delivery of chemicals to living cells. The device only needs a syringe pump, thus removing the use of complex, expensive external actuators. These tunable waveform microfluidic oscillators are envisioned to facilitate cell-based studies that require temporal stimulation.
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Affiliation(s)
- Sung-Jin Kim
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Ryuji Yokokawa
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, 48109, USA
- Department of Microengineering, Kyoto University, Yoshida-honmachi, Sakyo, Kyoto, 606-8501 JAPAN
| | | | - Shuichi Takayama
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, 48109, USA
- Department of Macromolecular Science and Engineering, University of Michigan, Ann Arbor, MI, 48109, USA
- Division of Nano-Bio and Chemical Engineering WCU Project, UNIST, Ulsan, Republic of Korea
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