Continuous Liquid Flow Research Articles

Continuous‐flow liquid microjunction surface sampling probe connected on‐line with high‐performance liquid chromatography/mass spectrometry for spatially resolved analysis of small molecules and proteins

A continuous-flow liquid microjunction surface sampling probe extracts soluble material from surfaces for direct ionization and detection by mass spectrometry. Demonstrated here is the on-line coupling of such a probe with high-performance liquid chromatography/mass spectrometry (HPLC/MS) enabling extraction, separation and detection of small molecules and proteins from surfaces in a spatially resolved (~0.5 mm diameter spots) manner. A continuous-flow liquid microjunction surface sampling probe was connected to a six-port, two-position valve for extract collection and injection to an HPLC column. A QTRAP® 5500 hybrid triple quadrupole linear ion trap equipped with a Turbo V™ ion source operated in positive electrospray ionization (ESI) mode was used for all experiments. The system operation was tested with the extraction, separation and detection of propranolol and associated metabolites from drug dosed tissues, caffeine from a coffee bean, cocaine from paper currency, and proteins from dried sheep blood spots on paper. Confirmed in the tissue were the parent drug and two different hydroxypropranolol glucuronides. The mass spectrometric response for these compounds from different locations in the liver showed an increase with increasing extraction time (5, 20 and 40 s). For on-line separation and detection/identification of extracted proteins from dried sheep blood spots, two major protein peaks dominated the chromatogram and could be correlated with the expected masses for the hemoglobin α and β chains. Spatially resolved sampling, separation, and detection of small molecules and proteins from surfaces can be accomplished using a continuous-flow liquid microjunction surface sampling probe coupled on-line with HPLC/MS detection.

Limitations of the exponential model for the correction for mass discrimination effects during isotope ratio measurements by MC-ICPMS. Demonstration with Sr at 5–15 μL min−1 continuous liquid flow rates

The need for performing isotope ratio measurements by MC-ICPMS on samples only available in small sizes and not allowing any dilution requires the development of sample introduction systems that can run below 10 μL min−1 sample flow rate (continuous mode). With a torch integrated sample introduction system (TISIS), optimisation of the running conditions involves the study of the temperature of the spray chamber (TSC). This paper investigates the consequences of changing TSC up to 100 °C and the sample flow rate down to 5 μL min−1 on mass discrimination effects. The validity of the exponential model commonly used to correct for these effects was tested for strontium isotopic measurements. Two categories of processes favouring the heaviest isotopes were envisaged: at plasma stage – “mechanism 1”, and within the ion beam – “mechanism 2”. The extraction potential applied inside the interface (HV1) was progressively increased, and results obtained for a range of approximately ±5 to 6 V around HV1 = 4004 V at 15 μL min−1 and TSC = 40 °C were used as reference. The intensity of mass discrimination effects increased at 15 μL min−1 and TSC = 60 or 100 °C, and decreased at 5 μL min−1 and TSC = 40 °C. At TSC = 100 °C (15 μL min−1) or at 5 μL min−1 (TSC = 40 °C) the stability of mass discrimination effects and the average efficiency of the exponential model were particularly degraded. The contribution of mechanism 1 (and its influence on mechanism 2) seemed to be the determining factor. At TSC = 100 °C the hypothesis made was the acceleration of the solvent evaporation process inside the TISIS, leading to variations in the characteristics of the tertiary aerosols. And the consequence was an increase of the plasma mass discriminative effects (ion diffusion) reinforced by the extra energy made available to the plasma ions. At 5 μL min−1, changes in the plasma composition arising from the reduction of the water load in combination with the ion production at an earlier stage within the plasma followed by the processes of ion diffusion were also hypothesized as possible causes for the inadequacy of the exponential model.

Mineralization of Calcium Carbonates in Cellulose Gel Membranes

AbstractA diffusion‐driven mineralization approach for the fabrication of calcium carbonate on and in regenerated and functionalized cellulose membranes was investigated. Calcium dichloride was used as the cation source. Ammonium carbonate was applied in a gas‐phase diffusion and sodium carbonate in a liquid continuous‐flow setup. Calcium carbonate was obtained solely on the membrane surfaces from the gas‐diffusion approach, whereas by applying continuous‐flow diffusion, crystals were obtained throughout the membranes. The main polymorph was calcite with minor fractions of aragonite. The crystals were assembled from nanometer‐sized building blocks and showed a strong interaction with the cellulose matrix under continuous liquid flow conditions. The cellulose membranes acted as an insoluble template matrix with a rigid and fine mesh of cellulose fibers as superstructure, thereby resulting in a structure‐directing microenvironment for the calcium carbonate mineralization in a confined space.

Micromechanical PDGF recognition via lab-on-a-disc aptasensor arrays

A plug-and-play CD-like platform is used to perform a statistical detection of platelet derived growth factor (PDGF) proteins through aptamer-based surface functionalization of multiple microcantilever arrays. When PDGF proteins bind to aptamer coatings, the cantilevers deflect. The deflection response is monitored by optical read-out units from a commercial DVD-ROM device. We report on the use of an improved sensing platform which facilitates measurements under continuous liquid flow and with temperature control. Also, the mechanical wobbling of the DVD-ROM platform has been minimized and the scanning system has been optimized in order to detect cantilever deflections in liquid with nanometer scale resolution. The capability of the sensing platform is demonstrated by detection of clinically relevant concentrations of PDGF proteins. We present statistical measurements on 100 microcantilevers at different concentrations of PDGF, ranging from 10nM to 400nM. Hereby it is possible to reliably characterize the averaged mechanical response of cantilevers as a function of protein concentration.

A Wet Electrostatic Precipitator (WESP) for Soft Nanoparticle Collection

Many nanoparticle collection devices have limitations related to retention of particle integrity from bounce, shattering, or aggregation. Suspensions of soft nanoparticles (e.g., proteins, lipids) are required for drug delivery and therapy. To enable direct collection of soft nanoparticles into liquid media, a wet electrostatic precipitator (WESP) was designed and evaluated in this work. Different sections were used for ion generation and particle charging, for minimal contact between the corona wire and particles, which were charged using positive nitrogen ions. WESP dimensions and operating parameters were optimized using charge distribution modeling. The prototype WESP was designed for operation with a continuous flow of liquid over the collection plate, to allow continuous particle collection from the exit stream of an aerosol reactor. The collection efficiency of the WESP, in dry and wet modes, was measured using aerosols of monodisperse polystyrene latex (PSL), polydisperse sucrose, and stearic acid (soft lipid) particles, through SMPS measurements, corrected for diffusional losses, at the entry and exit of the device. Measured collection efficiency was 70%–90% for particles of sizes 80–600 nm diameter in reasonable agreement with theoretical estimates. However, for small particles (20–80 nm diameter) measured collection efficiency ranged 40%–70%, significantly lower than theoretical estimates, possibly from incomplete neutralization of negative charges attained during air-jet atomization. Transmission electron microscopy (TEM) images and dynamic light scattering (DLS) measurements confirm that wet collection produces a suspension of free, unaggregated nanoparticles with sizes similar to their measured mean mobility diameter. Copyright 2012 American Association for Aerosol Research

Study of an ammonia-based wet scrubbing process in a continuous flow system

A continuous gas and liquid flow, regenerative scrubbing process for CO2 capture was demonstrated at the bench-scale level. An aqueous ammonia-based solution captures CO2 from simulated flue gas in an absorber and releases a nearly pure stream of CO2 in the regenerator. After the regeneration, the solution of ammonium compounds is recycled to the absorber. The design of a continuous flow unit was based on earlier exploratory results from a semi-batch reactor, where a CO2 and N2 simulated flue gas mixture flowed through a well-mixed batch of ammonia-based solution. During the semi-batch tests, the solution was cycled between absorption and regeneration steps to measure the carrying capacity of the solution at various initial ammonia concentrations and temperatures. Consequentially, a series of tests were conducted on the continuous unit to observe the effect of various parameters on CO2 removal efficiency and regenerator effectiveness within the flow system. The parameters that were studied included absorber temperature, regenerator temperature, initial NH3 concentration, simulated flue gas flow rate, liquid solvent inventory in the flow system, and height of the packed-bed absorber. From this testing and subsequent testing, ammonia losses from both the absorption and regeneration steps were quantified, and attempts were made to maintain steady state during operations. Implications of experimental results with respect to process design are discussed.

High Efficiency Mixing Chip with Liquid Flow Actuators Operated by Surface Acoustic Waves

SUMMARY Surface acoustic wave (SAW) devices can be used as component parts for micro total analysis systems (μTAS) because their structures are very simple. We thus fabricated a mixing chip with liquid flow actuators operated only by SAWs. The chip consists mainly of one Y-type flow channel, two pumps, and one mixer. The pumps are located in the upstream areas of the merging point of the flow channel, and the mixer is located in its downstream area. Additionally, the flow actuators have interdigital transducers (IDTs) to generate the SAWs. The IDTs were fabricated by patterning Al/Cr on a LiNbO3 substrate, and the flow channel wall was made of the epoxy-based negative resist SU-8. Using the mixing chip, we carried out a mixing experiment with two water solutions of different concentrations using glycerin, and a chemical reaction experiment involving luminol luminescence. Through the experiments, it was found that local and rapid mixing of a continuous liquid flow was possible by using the SAW actuators, and the capability of our fabricated mixing chip as a reactor was demonstrated. © 2013 Wiley Periodicals, Inc. Electron Comm Jpn, 97(1): 54–61, 2014; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/ecj.11440

A prototype continuous-flow liquid–liquid extraction system using open-source technology

A prototype continuous-flow liquid-liquid extraction system is reported. By harnessing several open-source software libraries, a computer control script was written using the Python programming language. Using a 'computer-vision' approach, this allowed the computer to monitor the interface level between the organic and aqueous phases using a simple webcam setup and (by dynamically controlling pump flow rate) to keep this interface within defined limits. The system enabled the efficient 'inline' extraction of excess reagent in hydrazone formations, dithiane formations and epoxidations. The initial results of dispersion measurement are also presented.

Sequential Continuous Flow Processes for the Oxidation of Amines and Azides by using HOF⋅MeCN

The generation and use of the highly potent oxidising agent HOF·MeCN in a controlled single continuous flow process is described. Oxidations of amines and azides to corresponding nitrated systems by using fluorine gas, water and acetonitrile by sequential gas-liquid/liquid-liquid continuous flow procedures are reported.

Tunnel Frit: A Nonmetallic In-Capillary Frit for Nanoflow Ultra High-Performance Liquid Chromatography–Mass SpectrometryApplications

In this study, an easy method to fabricate a durable in-capillary frit was developed for use in nanoflow liquid chromatography (nanoLC). A small orifice was tunneled into the sol-gel frit during the polymerization process resulting in the simple fabrication of a tunnel frit. A short packing tunnel frit column (2 cm, C(18) particles) was able to sustain over 10,000 psi continuous liquid flow for 10 days without observation of particle loss, and back pressure variation was less than 5%. The tunnel frit was successfully applied to the fabrication of nanoflow ultra high-performance liquid chromatography (nano-UHPLC) trap and analytical columns. In the analysis of tryptic peptides, the tunnel frit trap and analytical columns were demonstrated to have high separation efficiency and sensitivity. In analysis of phosphopeptides, the use of the nonmetallic tunnel frit column showed better sensitivity than the metallic frit column. This design can facilitate the preparation of nano-HPLC and nano-UHPLC columns and the packing material can easily be refilled when the column is severely contaminated or clogged.

Highly efficient liquid flow actuator operated by surface acoustic waves

AbstractSurface acoustic wave (SAW) devices, because of their very simple structures, can be used as component parts for micro total analysis systems. We focused on a liquid flow actuator operated by SAWs and investigated highly efficient interdigital transducers (IDTs) to generate SAWs. The IDTs were fabricated by patterning Al/Cr on a LiNbO3 substrate. In an IDT with a stripline pitch of 200 μm, effective water droplet streaming was produced. We also fabricated a continuous liquid flow actuator consisting of both an IDT and a flow channel made of epoxy‐based negative resist SU‐8 on one chip. To diversify the liquids used, we created an actuator design in which the IDT and liquid do not directly touch one another at the partition wall. Using this chip, we succeeded in creating a continuous flow of liquid using the SAWs. When 160 mW of electric power was applied, the liquid flow rate of the actuator was approximately 7.8 μL/s. We experimentally found that the electric power applied to the IDT was proportional to flow velocity and that the IDT with 200 μm pitch produced effective continuous liquid flow as well as water droplet streaming. © 2011 Wiley Periodicals, Inc. Electron Comm Jpn, 94(10): 10–16, 2011; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/ecj.10367

Solvation Structures of Iodide on and below a Surface of Aqueous Solution Studied by Photodetachment Spectroscopy

We investigated solvation structures of I(-) on and below a surface of an aqueous solution by photodetachment spectroscopy. An aqueous solution of an alkali halide was introduced to the vacuum as a continuous liquid flow (liquid beam), and the liquid beam was irradiated with a UV laser pulse. The intensity of electrons emitted from the surface by the laser excitation was measured as a function of wavelength (photodetachment spectroscopy), and we obtained absorption spectrum of I(-) on and below the solution surface. From the absorption spectrum, we found that I(-) starts to appear on the solution surface as the bulk NaI concentration increases. Similar concentration dependence was observed for the KI solution. We also found that I(-) located inside the solution is pushed to the surface, when NaCl is added to the solution. These changes are explained in terms of the difference in the polarizability of halide ions.

การบำบัดและการแยกน้ำเสียปนเปื้อนน้ำมันปาล์มด้วยกระบวนการอิเล็กโทรสตาติกโคอะเลสเซอร์ (Treatment and Separation of Palm Oily-Wastewater by Electrostatic Coalescer Process)

งานวิจัยนี้มีวัตถุประสงค์เพื่อศึกษาการบำบัดน้ำเสียปนเปื้อนน้ำมันปาล์มในรูปอิมัลชันที่มีสารลดแรงตึงผิวชนิดประจุลบ โดยประยุกต์ใช้กระบวนการรวมตะกอนทางไฟฟ้าร่วมกับอุปกรณ์โคอะเลสเซอร์ จากการศึกษาด้วยการเดินระบบแบบทีละเท พบว่าการเลือกใช้ขั้วอะลูมิเนียมที่ระยะห่าง 3 เซนติเมตรให้ประสิทธิภาพการบำบัดที่สูงกว่าการใช้ขั้วเหล็กและขั้วแกรไฟต์ที่ระยะห่างต่างๆ ซึ่งเป็นผลมาจากกลไกการตกตะกอนและลอยตะกอนทางไฟฟ้าที่แตกต่างกัน ทั้งในด้านความสามารถในการละลายของไอออนประจุบวกเพื่อทำลายเสถียรภาพอนุภาคน้ำมัน ความว่องไวในการทำปฏิกิริยา รวมถึงข้อจำกัดด้านอุทกพลศาสตร์ในการลอยตัวของฟองก๊าซที่เกิดขึ้น ทั้งนี้ เมื่อนำมาประยุกต์ใช้ร่วมกับอุปกรณ์โคอะเลสเซอร์ ที่ค่าอัตราการไหลที่เหมาะสมคือ 5 ลิตร / ชั่วโมงนั้น พบว่า สามารถเพิ่มประสิทธิภาพการบำบัดกว่า   2 เท่า (จาก 35 เป็น 70 เปอร์เซ็นต์) รวมถึงเพิ่มความหนาของชั้นน้ำมันเข้มข้นด้านบน เมื่อเดินระบบที่ค่าความต่างศักย์ต่ำๆ โดยแนวทางดังกล่าวสัมพันธ์กับ กลไกการรวมอนุภาคทางไฟฟ้า ซึ่งเหมาะสมกับการประยุกต์ใช้ในอนาคตเพื่อเพิ่มประสิทธิภาพการบำบัดและการนำกลับน้ำมันจากน้ำเสียปนเปื้อนน้ำมันที่มีความคงตัวสูง     Abstract The objective of this research was to study the treatment of palm oily-wastewater containing with anionic surfactant by combining Electro-coagulation (EC) and Coalescer processes. In batch process, the result has shown that the highest treatment efficiencies can be obtained with 3 cm aluminum electrode: the difference of electro-coagulation/flotation process in term of flotation mechanism, electrode dissolution and related bubble hydrodynamic / mixing parameters should be responsible for these results. By applying the suitable EC system with coalescer at 5 L/hr as continuous liquid flow rate, the treatment efficiencies can be enhanced for 2 times (from 35% to 70%) as well as, the oil layer thickness, especially at low voltage applied. In conclusion, this corresponds with e lectrostatic coalescence mechanism for applying, in future, to augment the treatment efficiency and also the oil recovery from stabilized oily-wastewater.

Solvation Structure of I− and Na+ on the Surface of NaI Aqueous Solution Studied by Photodetachment Spectroscopy in Combination with Mass Spectrometry

We investigated solvation structures of I(-) and Na(+) on an aqueous solution surface by photodetachment spectroscopy and mass spectrometry. An aqueous solution of NaI was introduced into the vacuum as a continuous liquid flow (liquid beam), and the liquid beam was irradiated with a UV laser pulse. The abundance of electrons emitted by the laser excitation was measured as a function of wavelength (photodetachment spectroscopy). For a concentrated aqueous solution of NaI, we observe an absorption peak at longer wavelengths than the charge-transfer-to-solvent band of I(-) in solution. This feature is assigned to the photoabsorption of I(-) at the surface. This finding indicates that when the concentration of NaI is high (>1.0 M), I(-) exists on the solution surface. The identity of the ion clusters ejected from the liquid beam following selective laser excitation of I(-) on the surface or I(-) inside the solution was revealed by mass spectrometry. The mass spectra show that Na rich clusters are formed when I(-) inside the solution is excited, whereas Na rich clusters are hardly formed by the excitation of surface I(-). These findings lead us to conclude that Na(+) does not exist on the surface of the NaI aqueous solution.

A novel all-in-one magnetic pump and power harvester design for bio-medicalapplications

This paper presents a magnetic centrifugal pump with a magnetic power harvester(all-in-one system) for medical applications. The proposed pump is driven by an externalrotating magnetic field. To produce pressure and electrical power, an all-in-one deviceconsisting of a pump and a power harvester was designed. It consists of a multi-stageimpeller, a disc type NdFeB permanent magnet, and a fixed wound coil on the pumpcase. The rotation of the rotor creates a continuous flow of liquid through thepump, with a pressure head, and an electrical power is generated in the wound coilbecause of the rotating magnetic field. The maximum flow rate and pressure are5000 ml min−1 and16 kPa, respectively, at 100 Hz. These results meet the requirements of an artificial heart assistanceblood pump. Under these operating conditions, the harvested voltage can reach a maximum of8.2 Vp−p. With this configuration and control method, wireless and battery-free operation ispossible, which is required in the medical field. Moreover, the power harvester can monitorthe pump conditions without additional electrical power and can provide electrical power toother implanted electrical devices. The performances of the pump and powerharvester were verified in a laboratory experiment. Overall, the proposed systemacts as a pump and a power harvester that is fully wireless and battery-free.

Superbase catalysts from thermally decomposed sodium azide supported on mesoporous γ-alumina

Mesoporous γ-alumina because of its homogeneous pore size distribution, represents a good support for alkali metals. Controlled thermal decomposition of impregnated sodium azide on such support yields a superbasic catalyst for the double bond migration of vinylcyclohexane to ethylidene cyclohexane in continuous liquid flow operation. After slurry impregnation of the azide in methanol, 23Na MAS NMR shows the presence of resonance lines corresponding to Na metal particles and sodium oxide on the support. When dry mixing of the catalyst components is done, only supported sodium oxide is found, in association with decreased catalytic activity. It is concluded that both species are necessary components of the superbasic sites required for the isomerization reaction mentioned. In the transesterification of soybean oil with methanol in a batch reactor, the same differences in activity are encountered. The 23Na MAS NMR spectrum of the former catalyst remained unchanged after the transesterification reaction.

Highly Efficient Liquid Flow Actuator Operated by Surface Acoustic Waves

Surface acoustic wave (SAW) devices, because of their very simple structures, can be used as component parts for micro total analysis systems. We focused on a liquid flow actuator operated by SAWs and investigated highly efficient interdigital transducers (IDTs) to generate SAWs. The IDTs were fabricated by patterning Al/Cr on a LiNbO3 substrate. In an IDT with a stripline pitch of 200μm, effective water droplet streaming was produced. We also fabricated a continuous liquid flow actuator consisting of both an IDT and a flow channel made of epoxy-based negative resist SU-8 on one chip. To diversify the liquids used, we created an actuator design in which the IDT and liquid do not directly touch one another at the partition wall. Using this chip, we succeeded in creating a continuous flow of liquid using the SAWs. When 160mW of electric power was applied, the liquid flow rate of the actuator was approximately 7.8μL/s. We experimentally found that the electric power applied to the IDT was proportional to flow velocity and that the IDT with 200μm pitch produced effective continuous liquid flow as well as water droplet streaming.

Ethylene removal using biotrickling filters: part II. Parameter estimation and mathematical simulation

Mathematical models of biofiltration often encounter uncertain parameters characterizing mass transfer, microbial degradation, biofilm growth, and biofilm detachment. The genetic algorithm, which is one of the most reliable methods for optimization although it has rarely been addressed in biofiltration models up to now, was utilized to estimate the unknown parameters using given experimental data. This study combined genetic algorithm and biofiltration equations to obtain simulated ethylene (C 2H 4) removal efficiencies with estimated parameters. Sensitivity analysis of each parameter was assessed to observe the significance of each parameter. As a result, the simulation well characterized C 2H 4 removal efficiencies for most of the reactors. The large difference in removal efficiencies among reactors could be mostly explained using the mass transfer parameters. Perlite biotrickling filters with low continuous liquid flow tended to increase C 2H 4 removal efficiencies, due to a large active surface area of biofilm facilitating C 2H 4 transfer from the gas to the biofilm phase. Conversely, most of the other reactors underwent relatively low C 2H 4 removal because of high liquid flow that generated a severe mass transfer limitation. The low C 2H 4 removal in the biofilters with discontinuous liquid recirculation flow, in spite of the lowest liquid flow rate was, probably caused by a low active microbial growth condition.

Determining the refractive index of liquids using a cylindrical cuvette

The refractive index of a liquid carries important information about its physical properties, including concentration and density, thus making it possible to determine and monitor the composition of the solution. This is important in fundamental research, chemical analysis and medical diagnostics, as well as in the processing and manufacturing of various substances. The authors have developed a compact and adaptable device of high sensitivity for measuring the refractive indices of both stationary liquids and continuous liquid flows. This device can be used in various technological processes requiring real-time analysis of flowing liquid substances, including aggressive compounds. The refractive index is determined by measuring the deviation of a laser beam passed through a cylindrical cuvette containing the test liquid. The magnitude of the deviation, which depends on the RI, is measured as the displacement of the transmitted beam's projection on a linear measuring element, such as a linear CMOS or CCD image sensor. In order to significantly improve the resolution and stability of RI measurements, an efficient solution has been developed, based on repeated reflection and refraction of the light beam travelling through the cylindrical cuvette with liquid. By this, deviation of the rays exiting the cuvette increases several times in respect to refractive index of the liquid. Additionally, a new method for detecting the position of the projected laser beam on a linear optical sensor is employed. Also, an increase in the intensity of the exiting rays has been achieved. By applying the techniques developed, it is possible to achieve high resolution and stability of refractive index measurements even when the distance between the image sensor and the cuvette is short. Hence, a basis for the construction of accurate and compact devices for determining the refractive indices of liquids is provided, suitable for a broad spectrum of applications.

Combined buoyancy and viscous effects in liquid–liquid flows in a vertical pipe

This paper presents experimental and numerical results of interfacial dynamics of liquid-liquid flows when an immiscible core liquid is introduced into a continuous liquid flow. The fully developed flow model predicts multiple solutions of the jet diameter over a range of dimensionless numbers: flow rate ratio, viscosity ratio, Bond and Capillary numbers. Experiments have been carried out using Polyethylene Glycol (PEG) and Canola oil to investigate the realizability of the three possible solutions predicted by the fully developed flow model. The measured values of inner fluid radii agree very well with the lower branch of the three branched solution while deviating from the top branch beyond a critical flow ratio value. This deviation is attributed to the fact that the flow develops a non-axisymmetric solution at this critical point. Computational fluid dynamics simulations have also been performed to examine the developing core annular flow and to compare the analytical solution results of liquid jet radius. The results predicted by numerical simulations agree very well with both the lower and upper branches of solution predicted by the analytical theory.