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1.
J Chromatogr A ; 1736: 465428, 2024 Nov 08.
Artículo en Inglés | MEDLINE | ID: mdl-39405636

RESUMEN

A metal tube-in-manifold packed bed capillary column device, designed to overcome common limitations associated with capillary LC separations, is described. Experimental results of initial packing tests with sub-3 µm core-shell particles demonstrated efficiencies greater than 47,000 plates/m for a separation performed using the column device. Computational fluid dynamics (CFD) modeling of the multicomponent separation used for this work was validated against experimental LC results and the optimized model was able to effectively predict component peak retention times. However, the accuracy of predicted efficiencies requires further refinement. The tube-in-manifold design demonstrates that packed capillary columns with cylindrical cross-sectional channel geometry and ultrahigh pressure, low dead volume fluidic connections are achievable.


Asunto(s)
Hidrodinámica , Simulación por Computador , Diseño de Equipo , Cromatografía Liquida/instrumentación , Cromatografía Liquida/métodos
2.
J Chromatogr A ; 1736: 465377, 2024 Nov 08.
Artículo en Inglés | MEDLINE | ID: mdl-39293278

RESUMEN

A nanospray emitter coupled to a supercritical fluid chromatograph (SFC-nSI-MS) for mass spectrometric (MS) analysis of fatty acids (FA) positional isomers is introduced. The experimental setup uses conventional bore columns before the SF back-pressure regulator (pre-BPR). The flow is then split and nanosprayed using a short emitter post-BPR. A C18 column was used to resolve positional isomers of unsaturated FA with a 5 min gradient. Chromatographic resolution of the nSFC was compared to a LC-MS system with superior resolving power demonstrated in the nSFC MS system. This system has proven quantitative performance for analyzing pharmaceutical effects on FA composition in a complex biological matrix like E coli lysate.


Asunto(s)
Cromatografía con Fluido Supercrítico , Ácidos Grasos , Cromatografía con Fluido Supercrítico/métodos , Ácidos Grasos/análisis , Ácidos Grasos/química , Isomerismo , Espectrometría de Masas/métodos , Espectrometría de Masa por Ionización de Electrospray/métodos , Escherichia coli/química
3.
J Sep Sci ; 47(9-10): e2400111, 2024 May.
Artículo en Inglés | MEDLINE | ID: mdl-38726734

RESUMEN

Electronic system control of analytical instrumentation remains a critical aspect of modern measurement science. Within the field of liquid chromatography (LC), this is especially relevant for automation, module operation, detection, data acquisition, and data analysis. Increasingly, home-built analytical tools used for liquid-phase separations rely upon open-source microcontrollers and single-board computers to aid in simplifying these operations. In this review, we detail literature reported within the past 5 years in which these types of devices were used to advance various aspects of the LC research field, including sample preparation, instrument control, and data collection.

4.
Brain Res ; 1839: 149040, 2024 Sep 15.
Artículo en Inglés | MEDLINE | ID: mdl-38815643

RESUMEN

Traumatic brain injury (TBI) is a complex pathophysiological process that results in a variety of neurotransmitter, behavioral, and cognitive deficits. The locus coeruleus-norepinephrine (LC-NE) system is a critical regulator of arousal levels and higher executive processes affected by TBI including attention, working memory, and decision making. LC-NE axon injury and impaired signaling within the prefrontal cortex (PFC) is a potential contributor to the neuropsychiatric symptoms after single, moderate to severe TBI. The majority of TBIs are mild, yet long-term cognitive deficits and increased susceptibility for further injury can accumulate after each repetitive mild TBI. As a potential treatment for restoring cognitive function and daytime sleepiness after injury psychostimulants, including methylphenidate (MPH) that increase levels of NE within the PFC, are being prescribed "off-label". The impact of mild and repetitive mild TBI on the LC-NE system remains limited. Therefore, we determined the extent of LC-NE and arousal dysfunction and response to therapeutic doses of MPH in rats following experimentally induced single and repetitive mild TBI. Microdialysis measures of basal NE efflux from the medial PFC and arousal measures were significantly lower after repetitive mild TBI. Females showed higher baseline PFC-NE efflux than males following single and repetitive mild TBI. In response to MPH challenge, males exhibited a blunted PFC-NE response and persistent arousal levels following repetitive mild TBI. These results provide critical insight into the role of catecholamine system dysfunction associated with cognitive deficits following repeated injury, outcome differences between sex/gender, and lack of success of MPH as an adjunctive therapy to improve cognitive function following injury.


Asunto(s)
Conmoción Encefálica , Estimulantes del Sistema Nervioso Central , Metilfenidato , Norepinefrina , Corteza Prefrontal , Ratas Sprague-Dawley , Animales , Masculino , Norepinefrina/metabolismo , Femenino , Corteza Prefrontal/metabolismo , Corteza Prefrontal/efectos de los fármacos , Estimulantes del Sistema Nervioso Central/farmacología , Metilfenidato/farmacología , Conmoción Encefálica/metabolismo , Conmoción Encefálica/fisiopatología , Conmoción Encefálica/tratamiento farmacológico , Ratas , Lesiones Traumáticas del Encéfalo/metabolismo , Lesiones Traumáticas del Encéfalo/tratamiento farmacológico , Lesiones Traumáticas del Encéfalo/fisiopatología , Locus Coeruleus/efectos de los fármacos , Locus Coeruleus/metabolismo , Nivel de Alerta/efectos de los fármacos , Nivel de Alerta/fisiología , Microdiálisis/métodos
5.
Anal Chem ; 96(11): 4693-4701, 2024 Mar 19.
Artículo en Inglés | MEDLINE | ID: mdl-38442211

RESUMEN

The cycle time of a standard liquid chromatography (LC) system is the sum of the time for the chromatographic run and the autosampler injection sequence. Although LC separation times in the 1-10 s range have been demonstrated, injection sequences are commonly >15 s, limiting throughput possible with LC separations. Further, such separations are performed on relatively large bore columns requiring flow rates of ≥5 mL/min, thus generating large volumes of mobile phase waste when used for large scale screening and increasing the difficulty in interfacing to mass spectrometry. Here, a droplet injector system was established that replaces the autosampler with a four-port, two-position valve equipped with a 20 nL internal loop interfaced to a syringe pump and a three-axis positioner to withdraw sample droplets from a well plate. In the system, sample and immiscible fluid are pulled alternately from a well plate into a capillary and then through the injection valve. The valve is actuated when sample fills the loop to allow sequential injection of samples at high throughput. Capillary LC columns with 300 µm inner diameter were used to reduce the consumption of mobile phase and sample. The system achieved 96 separations of 20 nL droplet samples containing 3 components in as little as 8.1 min with 5-s cycle time. This system was coupled to a mass spectrometer through an electrospray ionization source for high-throughput chemical reaction screening.

6.
Anal Chem ; 95(46): 17028-17036, 2023 11 21.
Artículo en Inglés | MEDLINE | ID: mdl-37943345

RESUMEN

High-throughput screening (HTS) workflows are revolutionizing many fields, including drug discovery, reaction discovery and optimization, diagnostics, sensing, and enzyme engineering. Liquid chromatography (LC) is commonly deployed during HTS to reduce matrix effects, distinguish isomers, and preconcentrate prior to detection, but LC separation time often limits throughput. Although subsecond LC separations have been demonstrated, they are rarely utilized during HTS due to limitations associated with the speed of common autosamplers. In this work, these limits are overcome by utilizing droplet microfluidics for sample introduction. In the method, a train of samples segmented by air are continuously pumped into the inlet of an LC injection valve that is actuated once each sample fills the sample loop. Coupled with 2.1 mm diameter × 5 mm long columns packed with 2.7 µm superficially porous C18 particles operated at 5 mL/min, the injector enabled separation of 3 components at 1 s/sample and analysis of a 96-well plate in 1.6 min with <2% peak area relative standard deviation. Analyte-dependent carryover was minimized by including wash droplets composed of organic solvent in between sample droplets. High-throughput LC coupled with mass spectrometric detection using the segmented flow injector was applied to a screen of inhibitors of a cytochrome P450-catalyzed hydroxylation reaction. Measurements of the reaction substrate and product concentrations made using fast LC with the segmented flow injector correlated well with measurements made using a more conventional, 3 min LC method. These results demonstrate the potential for droplet microfluidics to be used for sample introduction during high-throughput LC analysis.


Asunto(s)
Microfluídica , Cromatografía Liquida/métodos , Espectrometría de Masas/métodos
7.
J Sep Sci ; 46(18): e2300343, 2023 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-37603367

RESUMEN

The analysis of organic acids in complex mixtures by LC-MS can often prove challenging, especially due to the poor sensitivity of negative ionization mode required for detection of these compounds in their native (i.e., underivatized or untagged) form. These compounds have also been difficult to measure using supercritical fluid chromatography (SFC)-MS, a technique of growing importance for metabolomic analysis, with similar limitations based on negative ionization. In this report, the use of a high proton affinity N-(4-aminophenyl)piperidine derivatization tag is explored for the improvement of organic acid detection by SFC-MS. Four organic acids (lactic, succinic, malic, and citric acids) with varying numbers of carboxylate groups were derivatized with N-(4-aminophenyl)piperidine to achieve detection limits down to 0.5 ppb, with overall improvements in detection limit ranging from 25-to-2100-fold. The effect of the derivatization group on sensitivity, which increased by at least 200-fold for compounds that were detectable in their native form, and mass spectrometric detection are also described. Preliminary investigations into the separation of these derivatized compounds identified multiple stationary phases that could be used for complete separation of all four compounds by SFC. This derivatization technique provides an improved approach for the analysis of organic acids by SFC-MS, especially for those that are undetectable in their native form.

8.
LC GC Eur ; 36(Suppl 5): 24-27, 2023 May.
Artículo en Inglés | MEDLINE | ID: mdl-37484870

RESUMEN

A recent trend in the design of liquid chromatography (LC) instrumentation is the move towards miniaturized and portable systems. These smaller platforms provide wider flexibility in operation, with the opportunity for conducting analysis directly at the point of sample collection rather than transporting the sample to a centralized laboratory facility. For the manufacturing of pharmaceutical and biopharmaceutical products, these platforms can be implemented for process monitoring and product characterization directly in manufacturing environments. This article describes a portable, miniaturized LC instrument coupled to a mass spectrometer (MS) for characterization of a biopharmaceutical monoclonal antibody (mAb).

9.
J Chromatogr A ; 1701: 464067, 2023 Jul 19.
Artículo en Inglés | MEDLINE | ID: mdl-37216851

RESUMEN

Recent years have seen significant advances in compact, portable capillary LC instrumentation. This study explores the performances of several commercially available columns within the pressure and flow limits of both the columns and one of these compact LC instruments. The commercially available compact capillary LC system with UV-absorbance detector used in this study is typically operated using columns in the 0.15-0.3 mm internal diameter (i.d.) range. Efficiency measurements (i.e., theoretical plates, N) for six columns with i.d.s in this range and of varying lengths and pressure limits, packed with stationary phases of different particle diameters and morphologies, were made using a mixture of standard alkylphenones. Kinetic plot comparisons between columns that vary by one (or more) of these parameters are described, along with calculated kinetic performance and Knox-Saleem limits. These theoretical performance descriptions provide insight into optimal operating conditions when using capillary LC systems. Based on kinetic plot evaluation of available capillary columns in the 0.2-0.3 mm i.d. range with a conservative upper pressure limit of 330 bar packed with superficially porous particles, a 25 cm column could generate ∼47,000 plates in 7.85 min when operated at 2.4 µL/min. For comparison, more robust 0.3 mm i.d. columns (packed with fully porous particles) that can be operated at higher pressures than can be provided by the pumping system (conservative pump upper pressure limit of 570 bar), a ∼20 cm column could generate nearly 40,000 plates in 5.9 min if operated at 6 µL/min. Across all capillary LC columns measured, higher pressure limits and shorter columns can provide the best throughput when considering both speed and efficiency.


Asunto(s)
Tamaño de la Partícula , Cromatografía Liquida/métodos , Cinética , Porosidad , Cromatografía Líquida de Alta Presión/métodos
10.
J Am Soc Mass Spectrom ; 34(6): 995-1005, 2023 Jun 07.
Artículo en Inglés | MEDLINE | ID: mdl-37097105

RESUMEN

Nanospraying supercritical fluids coupled to a mass spectrometer (nSF-MS) using a 90% supercritical fluid CO2 carrier (sCO2) has shown an enhanced desolvation compared to traditional liquid eluents. Capillaries of 25, 50, and 75 µm internal diameter (i.d.) with pulled emitter tips provided high MS detection sensitivity. Presented here is an evaluation of the effect of proton affinity, hydrophobicity, and nanoemitter tip size on the nSF-MS signal. This was done using a set of primary, secondary, tertiary, and quaternary amines with butyl, hexyl, octyl, and decyl chains as analytes. Each amine class was analyzed individually to evaluate hydrophobicity and proton affinity effects on signal intensity. The system has shown a mass sensitive detection on a linear dynamic range of 0.1-100 µM. Results indicate that hydrophobicity has a larger effect on the signal response than proton affinity. Nanospraying a mixture of all amine classes using the 75 µm emitter has shown a quaternary amine signal not suppressed by competing analytes. Competing ionization was observed for primary, secondary, and tertiary amines. The 75 and 50 µm emitters demonstrated increased signal with increasing hydrophobicity. Surprisingly, the 25 µm i.d. emitter yielded a signal decrease as the alkyl chain length increased, contrary to conventional understanding. Nanospraying the evaporative fluid in a sub-500 nm emitter likely resulted in differences in the ionization mechanism. Results suggest that 90% sCO2 with 9.99% methanol and 0.01% formic acid yielded fast desolvation, high ionization efficiency, and low matrix effect, which could benefit complex biological matrix analysis.

11.
Anal Bioanal Chem ; 415(18): 4147-4152, 2023 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-36707447

RESUMEN

Emitter tip arrays for electrospray ionization have been used for a variety of MS sample introduction purposes, including detection of multiple sample eluent streams and improved accuracy through parallel infusion of an internal standard. User control is typically required for targeted application of high voltage to specific channels to maximize analyte signal and minimize other background signals. In this communication, an automated approach to applying electrospray voltage only when a detectable analyte is present is described. An in-line absorbance detector is used to identify the presence of an analyte in the fluidic path between the sample introduction valve and the mass spectrometer. A Raspberry Pi-controlled system is then used to apply high voltage to a downstream emitter tip at the MS inlet following a delay volume between the detectors. Demonstration of this technique on two parallel sample channels is reported, including a pulsed voltage application to maximize signal when analytes elute on each channel simultaneously.

12.
J Am Soc Mass Spectrom ; 33(10): 1825-1832, 2022 Oct 05.
Artículo en Inglés | MEDLINE | ID: mdl-36049155

RESUMEN

Supercritical fluids are typically electrosprayed using an organic solvent makeup flow to facilitate continuous electrical connection and enhancement of electrospray stability. This results in sample dilution, loss in sensitivity, and potential phase separation. Premixing the supercritical fluid with organic solvent has shown substantial benefits to electrospray efficiency and increased analyte charge state. Presented here is a nanospray mass spectrometry system for supercritical fluids (nSF-MS). This split flow system used small i.d. capillaries, heated interface, inline frit, and submicron emitter tips to electrospray quaternary alkyl amines solvated in supercritical CO2 with a 10% methanol modifier. Analyte signal response was evaluated as a function of total system flow rate (0.5-1.5 mL/min) that is split to nanospray a supercritical fluid with linear flow rates between 0.07 and 0.42 cm/sec and pressure ranges (15-25 MPa). The nSF system showed mass-sensitive detection based on increased signal intensity for increasing capillary i.d. and analyte injection volume. These effects indicate efficient solvent evaporation for the analysis of quaternary amines. Carrier additives generally decreased signal intensity. Comparison of the nSF-MS system to the conventional SF makeup flow ESI showed 10-fold signal intensity enhancement across all the capillary i.d.s. The nSF-MS system likely achieves rapid solvent evaporation of the SF at the emitter point. The developed system combined the benefits of the nanoemitters, sCO2, and the low modifier percentage which gave rise to enhancement in MS detection sensitivity.


Asunto(s)
Dióxido de Carbono , Metanol , Aminas , Espectrometría de Masas/métodos , Solventes/química , Espectrometría de Masa por Ionización de Electrospray/métodos
13.
Anal Chim Acta ; 1228: 340300, 2022 Oct 02.
Artículo en Inglés | MEDLINE | ID: mdl-36127000

RESUMEN

Multi-dimensional liquid chromatography techniques play an important role in the analysis of complex mixtures. The keys to maximizing peak capacity in these methods are fast sampling rates and sufficient complementarity between the first- (1D) and second- (2D) dimension separations. One way that these criteria have been met is by using 2D parallel column arrays. This review covers demonstrations of this approach in the literature that have been published over the past three decades. Two or more identical 2D columns can be operated in a sequential order to permit increased separation times and higher peak capacities in the second dimension without the concomitant decrease in sampling rate. The parallel column arrays can also be operated simultaneously to reduce total analysis time. Columns with different stationary phase chemistries can be used in the 2D column array to increase complementarity by utilizing specific stationary phases for various first dimension fractions. More recently, this type of platform has been used to automate the development of two-dimensional (2D) achiral-chiral LC methods. These strategies, as well as recent efforts toward the development of integrated, spatial multi-dimensional LC devices that include parallel column arrays, are discussed here.


Asunto(s)
Mezclas Complejas , Cromatografía Liquida/métodos
14.
Chromatographia ; 85(8): 681-688, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35875830

RESUMEN

A number of recommendations on how to improve the education and training of separation scientists were recently made by the National Academies of Sciences, Engineering, and Mathematics in their report, A Research Agenda for Transforming Separation Science. This perspective outlines how some of these recommendations may be fulfilled by examining trends in potential curriculum topics related to the field and new technological platforms for interactive content delivery. Identifying and adopting the best practices within these emerging educational directions will ensure the future success of the field.

15.
J Chromatogr A ; 1676: 463207, 2022 Aug 02.
Artículo en Inglés | MEDLINE | ID: mdl-35732094

RESUMEN

The use of smaller column diameters in liquid chromatography (LC) is often associated with capillary LC. Although there are many analytical benefits gained by adapting this format, routine use continues to be challenging due to column fragility and extra column dispersion. Bridging the gap between routinely used 2.1 mm columns and capillary bore columns allows for a sequential but far from insignificant increase in performance without the need for specialized equipment associated with very low dispersion LC systems. Moreover, an incremental decrease in column internal diameter (i.d.) allows for similar mass load (avoiding column overload that may be observed in much larger decreases in i.d. without trapping) and thus an increase in measured signal. As such, 1.5 mm i.d. columns provide an alternative intermediate dimension between the more regularly used 2.1 mm i.d. columns and 1 mm i.d. columns. These columns balance an increase in sensitivity compared to 2.1 mm i.d. columns (theoretically doubling the time-domain peak area in mass sensitive detectors for the same mass load), while mitigating the efficiency losses due to extra-column dispersion effects that are commonly observed with 1.0 mm i.d. columns. Here, the use of 1.5 mm i.d. columns was applied to LC/UV analysis of small molecules and LC/MS methods for the analysis of monoclonal antibodies. With equivalent mass load on column, the 1.5 mm i.d. columns provide two-to-threefold improvement in analyte peak area signal for small molecules as well as intact, subunit, and peptide levels of antibody analysis. Peak height was also increased using the 1.5 mm i.d. column, although the scale of increase varies between isocratic and gradient modes, likely due to differences in system dispersion effects and variation in electrospray ionization efficiency at different flow rates.


Asunto(s)
Anticuerpos , Péptidos , Cromatografía Líquida de Alta Presión/métodos , Cromatografía Liquida , Péptidos/química , Flujo de Trabajo
16.
J Chromatogr A ; 1670: 462952, 2022 May 10.
Artículo en Inglés | MEDLINE | ID: mdl-35339020

RESUMEN

LC-MS metabolomic analysis in complex biological matrices may be complicated by degeneracy when using large-bore columns. Degeneracy is the detection of multiple mass spectral peaks from the same analyte due to adduction of salts to the metabolite, dimerization, or loss of neutrals. This introduces interferences to the MS spectra, diminishes quantification, and increases the rate of false identifications. Analysis using 2.1 mm inner diameter (i.d.) columns typically leads to degenerate peaks whereas nanospray using capillary columns (25, 50, and 75 µm i.d.) reduces degeneracy. Optimization of chromatographic parameters of capillary LC for amino acid standards showed the lowest HETP at 1.25 mm/sec across all capillary i.d. columns. Results suggest mass-sensitive detection below the optimum velocity. At faster velocities, concentration-dependent detection occurred across all capillaries. The 2.1 mm i.d. analytical scale column showed the greatest level of degeneracy, particularly in the low signal intensity range. 25 µm i.d. columns showed higher levels of metabolite annotation for the same signal intensity range. It also provided the lowest level of degeneracy, making it best suited for untargeted analysis. The 25 µm i.d. column achieved a peak capacity (nc) of 144 in a 30-minute gradient method with nc decreasing as the column i.d. increased. 75 µm i.d. capillary columns showed the highest signal intensity, which is beneficial for targeted analysis. These effects of chromatographic performance, resolution, and degeneracy profile of capillary and analytical scale columns were compared for metabolomic analyses in complex serum and cell lysate matrices.


Asunto(s)
Capilares , Espectrometría de Masas en Tándem , Cromatografía Liquida , Metabolómica
17.
Sep Sci Plus ; 5(6): 213-219, 2022 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-37008988

RESUMEN

A wide variety of analytical techniques have been employed for monitoring chemical reactions, with online instrumentation providing additional benefits compared to offline analysis. A challenge in the past for online monitoring has been placement of the monitoring instrumentation as close as possible to the reaction vessel to maximize sampling temporal resolution and preserve sample composition integrity. Furthermore, the ability to sample very small volumes from bench-scale reactions allows the use of small reaction vessels and conservation of expensive reagents. In this study, a compact capillary LC instrument was used for online monitoring of as small as 1 mL total volume of a chemical reaction mixture, with automated sampling of nL-scale volumes directly from the reaction vessel used for analysis. Analyses to demonstrate short term (~2 h) and long term (~ 50 h) reactions were conducted using tandem on-capillary ultraviolet absorbance followed by in-line MS detection or ultraviolet absorbance detection alone, respectively. For both short term and long term reactions (10 and 250 injections, respectively), sampling approaches using syringe pumps minimized the overall sample loss to ~0.2% of the total reaction volume.

18.
J Chromatogr A ; 1659: 462645, 2021 Dec 06.
Artículo en Inglés | MEDLINE | ID: mdl-34731749

RESUMEN

Method development in gradient LC relies upon the selection of a solvent time program and a mobile phase flow rate. The flow rate, optimal for gradient separation cannot be inherently predicted by the isocratic value optimal for a given analyte, and rather should be identified independently to ensure the highest separation performance of gradient analysis. The optimal flow rate (Fopt) is defined herein as the solvent volumetric flow rate (F) maximizing the separation (Δs) of a predetermined peak-pair or the separation capacity (sc) of the entire LC analysis. The theoretical background and the experimental technique of measurement of Fopt in gradient elution analysis were considered and experimentally demonstrated. The technique of measuring Fopt is based on translatable changes of F where the product FtG (tG is the gradient time) was the same for all values of F. The Fopt was found as F corresponding to the maximum in Δs or in sc.


Asunto(s)
Cromatografía Liquida , Cromatografía Líquida de Alta Presión , Solventes
19.
HardwareX ; 102021 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-34553104

RESUMEN

Robotic positioning systems are used in a variety of chemical instruments, primarily for liquid handling purposes, such as autosamplers from vials or well plates. Here, two approaches to the design of open-source autosampler positioning systems for use with 96-well plates are described and compared. The first system, a 3-axis design similar to many low-cost 3D printers that are available on the market, is constructed using an aluminum design and stepper motors. The other system relies upon a series of 3D printed parts to achieve movement with a series of linker arms based on Selective Compliance Assembly Robot Arm (SCARA) design principles. Full printer design files, assembly instructions, software, and user directions are included for both samplers. The positioning precision of the 3-axis system is better than the SCARA mechanism due to finer motor control, albeit with a slightly higher cost of materials. Based on the improved precision of this approach, the 3-axis autosampler system was used to demonstrate the generation of a segmented flow droplet stream from adjacent wells within a 96-well plate.

20.
Anal Chim Acta ; 1151: 338230, 2021 Mar 22.
Artículo en Inglés | MEDLINE | ID: mdl-33608076

RESUMEN

Many laboratory applications utilizing droplet microfluidics rely on precision syringe pumps for flow generation. In this study, the use of an open-source peristaltic pump primarily composed of 3D printed parts and a low-cost commercial Venturi pump are explored for their use as an alternative to syringe pumps for droplet microfluidics. Both devices provided stable flow (<2% RSD) over a range of 1-7 µL/min and high reproducibility in signal intensity at a droplet generation rate around 0.25 Hz (<3% RSD), which are comparable in performance to similar measurements on standard syringe pumps. As a novel flow generation source for microfluidic applications, the use of the miniaturized Venturi pump was also applied to droplet signal monitoring studies used to measure changes in concentration over time, with average signal reproducibility <4% RSD for both single-stream fluorometric and reagent addition colorimetric applications. These low-cost flow methods provide stable flow sufficient for common droplet microfluidic approaches and can be implemented in a wide variety of simple, and potentially portable, analytical measurement devices.

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