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Warren CG, Dasgupta PK. Liquid phase detection in the miniature scale. Microfluidic and capillary scale measurement and separation systems. A tutorial review. Anal Chim Acta 2024; 1305:342507. [PMID: 38677834 DOI: 10.1016/j.aca.2024.342507] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Revised: 03/18/2024] [Accepted: 03/19/2024] [Indexed: 04/29/2024]
Abstract
Microfluidic and capillary devices are increasingly being used in analytical applications while their overall size keeps decreasing. Detection sensitivity for these microdevices gains more importance as device sizes and consequently, sample volumes, decrease. This paper reviews optical, electrochemical, electrical, and mass spectrometric detection methods that are applicable to capillary scale and microfluidic devices, with brief introduction to the principles in each case. Much of this is considered in the context of separations. We do consider theoretical aspects of separations by open tubular liquid chromatography, arguably the most potentially fertile area of separations that has been left fallow largely because of lack of scale-appropriate detection methods. We also examine the theoretical basis of zone electrophoretic separations. Optical detection methods discussed include UV/Vis absorbance, fluorescence, chemiluminescence and refractometry. Amperometry is essentially the only electrochemical detection method used in microsystems. Suppressed conductance and especially contactless conductivity (admittance) detection are in wide use for the detection of ionic analytes. Microfluidic devices, integrated to various mass spectrometers, including ESI-MS, APCI-MS, and MALDI-MS are discussed. We consider the advantages and disadvantages of each detection method and compare the best reported limits of detection in as uniform a format as the available information allows. While this review pays more attention to recent developments, our primary focus has been on the novelty and ingenuity of the approach, regardless of when it was first proposed, as long as it can be potentially relevant to miniature platforms.
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Affiliation(s)
- Cable G Warren
- Department of Chemistry and Biochemistry, University of Texas at Arlington, Arlington, TX, 76019-0065, United States
| | - Purnendu K Dasgupta
- Department of Chemistry and Biochemistry, University of Texas at Arlington, Arlington, TX, 76019-0065, United States.
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2
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De Silva M, Dunn RC. Electric field-enhanced backscatter interferometry detection for capillary electrophoresis. Sci Rep 2024; 14:2110. [PMID: 38267528 PMCID: PMC10808210 DOI: 10.1038/s41598-024-52621-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Accepted: 01/22/2024] [Indexed: 01/26/2024] Open
Abstract
Backscatter interferometry (BSI) is a refractive index (RI) detection method that is easily integrated with capillary electrophoresis (CE) and is capable of detecting species ranging from inorganic ions to proteins without additional labels or contrast agents. The BSI signal changes linearly with the square of the separation voltage which has been used to quantify sample injection, but has not been explored as a potential signal enhancement mechanism in CE. Here we develop a mathematical model that predicts a signal enhancement at high field strengths, where the BSI signal is dominated by the voltage dependent mechanism. This is confirmed in both simulation and experiment, which show that the analyte peak area grows linearly with separation voltage at high field strengths. This effect can be exploited by adjusting the background electrolyte (BGE) to increase the conductivity difference between the BGE and analyte zones, which is shown to improve BSI performance. We also show that this approach has utility in small bore capillaries where larger separation fields can be applied before excess Joule heating degrades the separation. Unlike other optical detection methods that generally degrade as the optical pathlength is reduced, the BSI signal-to-noise can improve in small bore capillaries as the larger separation fields enhance the signal.
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Affiliation(s)
- Miyuru De Silva
- Department of Chemistry, University of Kansas, Lawrence, KS, 66047, USA
| | - Robert C Dunn
- Department of Chemistry, University of Kansas, Lawrence, KS, 66047, USA.
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3
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Peng H, Kong S, Deng X, Deng Q, Qi F, Liu C, Tang R. Development of a Ratiometric Fluorescent Probe with Zero Cross-Talk for the Detection of SO 2 Derivatives in Foods and Live Cells. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2023; 71:14322-14329. [PMID: 37747790 DOI: 10.1021/acs.jafc.3c04056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/26/2023]
Abstract
Sulfur dioxide (SO2) derivatives are extensively utilized as both a preservative for foods and an active gaseous signal molecule in various physiological and pathological processes, but their excessive intake would bring harmful effects on human health; so, the determination of SO2 derivatives is of great importance. Herein, we developed a ratiometric fluorescent probe named 2-(2'-hydroxyphenyl)benzothiazole-3-ethyl-1,1,2-trimethyl-1H-benzo[e]indolium (HBT-EMBI) by introducing a hemicyanine unit of EMBI to an HBT group for the detection of SO2 derivatives via an excited-state intramolecular proton transfer (ESIPT) and intramolecular charge transfer (ICT) effects. The probe displays some advantages, such as a colorimetric change from purple to colorless, a ratiometric fluorescence with zero cross-talk, and a remarkably large emission shift (Δλ = 164 nm) under a single-wavelength excitation. Accordingly, the probe HBT-EMBI has been successfully employed for the colorimetric and ratiometric determination of SO2 derivatives in real food samples and the quantitative visualization of SO2 derivative variations in HepG2 cells.
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Affiliation(s)
- Huan Peng
- College of Material and Chemical Engineering, Hunan City University, Yiyang 413000, People's Republic of China
- School of Chemistry and Chemical Engineering, Central South University, Changsha 410083, People's Republic of China
| | - Suna Kong
- School of Chemistry and Chemical Engineering, Central South University, Changsha 410083, People's Republic of China
| | - Xia Deng
- School of Chemistry and Chemical Engineering, Central South University, Changsha 410083, People's Republic of China
| | - Qirong Deng
- School of Chemistry and Chemical Engineering, Central South University, Changsha 410083, People's Republic of China
| | - Fengpei Qi
- College of Material and Chemical Engineering, Hunan City University, Yiyang 413000, People's Republic of China
| | - Changhui Liu
- College of Material and Chemical Engineering, Hunan City University, Yiyang 413000, People's Republic of China
| | - Ruiren Tang
- School of Chemistry and Chemical Engineering, Central South University, Changsha 410083, People's Republic of China
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Liu X, Liang W, Zeng H, Jiang Y, Li Y, Zhang M. 3D printed cartridge for high-speed capillary electrophoresis with sheath liquid thermostatting and contactless conductivity detection. Anal Chim Acta 2023; 1264:341235. [PMID: 37230716 DOI: 10.1016/j.aca.2023.341235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 04/15/2023] [Accepted: 04/18/2023] [Indexed: 05/27/2023]
Abstract
The high-speed capillary electrophoresis (HSCE) method is a technique that utilizes a high electric field strength applied through a short capillary to reduce the time required for sample separation. However, the increased electric field strength may result in pronounced Joule heating effects. To address this, we describe a 3D-printed cartridge with integrated contactless conductivity detection (C4D) head and a sheath liquid channel. The C4D electrodes and Faraday shield layers are fabricated by casting Wood's metal in chambers inside the cartridge. Effective thermostatting of the short capillary is achieved by flowing Fluorinert liquid, which provides better heat dissipation compared to airflow. A HSCE device is created by using the cartridge and a modified slotted-vial array sample-introduction approach. Analytes are introduced through electrokinetic injection. With the help of sheath liquid thermostatting, background electrolyte concentration can be increased to several hundred mM, resulting in improved sample stacking and peak resolutions. Additionally, the baseline signal is flattened. Typical cations such as NH4+, K+, Na+, Mg2+, Li+, and Ca2+ can be separated within 22 s with an applied field strength of 1200 V/cm. The limit of detection ranges from 2.5 to 4.6 μM with a relative standard deviation of migration times of 1.1-1.2% (n = 17). The method has been applied to detect cations in drinking water and black tea leaching for drink safety testing, and to identify explosive anions in paper swabs. Samples can be directly injected without the need for dilution.
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Affiliation(s)
- Xing Liu
- School of Life and Environmental Sciences, Guilin University of Electronic Technology, Guilin, Guangxi, 541004, China
| | - Wenshan Liang
- School of Life and Environmental Sciences, Guilin University of Electronic Technology, Guilin, Guangxi, 541004, China
| | - Hui Zeng
- School of Life and Environmental Sciences, Guilin University of Electronic Technology, Guilin, Guangxi, 541004, China.
| | - Yiyu Jiang
- School of Life and Environmental Sciences, Guilin University of Electronic Technology, Guilin, Guangxi, 541004, China
| | - Yan Li
- School of Life and Environmental Sciences, Guilin University of Electronic Technology, Guilin, Guangxi, 541004, China
| | - Min Zhang
- School of Life and Environmental Sciences, Guilin University of Electronic Technology, Guilin, Guangxi, 541004, China.
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De Silva M, Dunn RC. Sample plug induced peak splitting in capillary electrophoresis studied using dual backscattered interferometry and fluorescence detection. Electrophoresis 2023; 44:549-557. [PMID: 36641782 DOI: 10.1002/elps.202200244] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Revised: 12/07/2022] [Accepted: 01/03/2023] [Indexed: 01/16/2023]
Abstract
The appearance of unexpected peaks in capillary electrophoresis (CE) is common and can lengthen the time of method development as assay conditions and experimental parameters are varied to understand and mitigate the effects of the additional peaks. Additional peaks can arise when a single-analyte zone is split into multiple zones. Understanding the underlying mechanism of these phenomena, recognizing conditions that favor its presence, and knowing how to confirm and eliminate the effect are important for efficient method optimization. In this study, we examine how the overlap of analyte zones with the sample plug can lead to peak splitting. This is explored experimentally using dual detection CE, which enables both the sample plug and analyte zones to be independently and simultaneously measured from the same detection volume. Simulations performed via COMSOL Multiphysics confirm the origin of the splitting and help guide experiments to reduce and eliminate the effect. Our findings show that this peak splitting mechanism can arise in separations of both small and large molecules but is, especially, prevalent in separations of slowly migrating macromolecules. This effect is also more prevalent when using a short length-to-detector, as is commonly found in microfluidic applications. A simple diffusion-less model is introduced to develop strategies for reducing peak splitting that avoids modifying the apparatus, such as by lengthening the separation length, which can be difficult. Decreasing the sample plug length and slowing the electroosmotic flow can both reduce this effect, which is confirmed experimentally.
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Affiliation(s)
- Miyuru De Silva
- Ralph N. Adams Institute for Bioanalytical Chemistry, University of Kansas, Lawrence, Kansas, USA
| | - Robert C Dunn
- Ralph N. Adams Institute for Bioanalytical Chemistry, University of Kansas, Lawrence, Kansas, USA
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Novel developments in capillary electrophoresis miniaturization, sampling, detection and portability: An overview of the last decade. Trends Analyt Chem 2023. [DOI: 10.1016/j.trac.2023.116941] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Kurzyna-Szklarek M, Cybulska J, Zdunek A. Analysis of the chemical composition of natural carbohydrates - An overview of methods. Food Chem 2022; 394:133466. [PMID: 35716502 DOI: 10.1016/j.foodchem.2022.133466] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Revised: 05/13/2022] [Accepted: 06/09/2022] [Indexed: 11/19/2022]
Abstract
Natural carbohydrates are gaining importance over a wide spectrum of human activity due to their versatile functionalities. The properties of carbohydrates are currently used in many branches of industry and new possibilities of their utilization, like in medicine or materials science, are demonstrated systematically. The attractive properties of carbohydrates result from their chemical structure and ability to form macromolecules and derivatives. Each application of carbohydrate requires a knowledge of their chemical composition, which due to the number and differentiation of monosaccharides and their spatial forms is often challenging. This review presents an overview on sample preparation and the methods used for the determination of the fine chemical structure of natural carbohydrates. Most popular and reliable colorimetric, chromatographic and spectroscopic methods are presented with an emphasis on their pros and cons.
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Affiliation(s)
| | - Justyna Cybulska
- Institute of Agrophysics, Polish Academy of Sciences, Doświadczalna 4, 20-290 Lublin, Poland.
| | - Artur Zdunek
- Institute of Agrophysics, Polish Academy of Sciences, Doświadczalna 4, 20-290 Lublin, Poland
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Yang L, Pan G, Zhang P, Liu Q, Liu X, Li Y, Liang Y, Zhang M. 3D printed two-in-one on-capillary detector: Combining contactless conductometric and photometric detection for capillary electrophoresis. Anal Chim Acta 2021; 1159:338427. [PMID: 33867034 DOI: 10.1016/j.aca.2021.338427] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Revised: 02/23/2021] [Accepted: 03/15/2021] [Indexed: 10/21/2022]
Abstract
In this work, for the first time, a 3D printed two-in-one on-capillary detector, combining contactless conductometric detection (C4D) and photometric detection (PD), is fabricated for capillary electrophoresis (CE). The C4D Faraday shield (FS) is printed using electrically conductive composite polylactic acid (PLA) to minimize the stray capacitance. Non-conductive PLA is also used to print the insulator of FS to prevent the electrical conduction with two stainless steel electrodes. A novel collimator, consisting of two partially aligned pinholes, is printed by conductive material to collimate the light-emitting diode beam. The C4D detection has a signal-to-noise ratio of 1092 ± 2 for 200 μM potassium on a 25 μm id capillary. The PD detection shows excellent linearity with stray light down to 8% and an effective path length at 73% of a 75 μm id capillary. The analytical performance is demonstrated by CE separation and detection of cations. PD shows limits of detection (LODs) of 1.3, 0.9, and 1.7 μM for cobalt, copper and zinc, which are complexed with 4-(2-Pyridylazo) resorcinol, while C4D shows LODs of 1.2, 1.4, 21 and 2.6 μM for potassium, sodium, cobalt and zinc, respectively.
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Affiliation(s)
- Liye Yang
- School of Life and Environmental Sciences, Guangxi Key Laboratory of Automatic Detecting Technology and Instruments, Guilin University of Electronic Technology, Guilin, Guangxi, 541004, China
| | - Guangchao Pan
- School of Life and Environmental Sciences, Guangxi Key Laboratory of Automatic Detecting Technology and Instruments, Guilin University of Electronic Technology, Guilin, Guangxi, 541004, China
| | - Piwang Zhang
- School of Life and Environmental Sciences, Guangxi Key Laboratory of Automatic Detecting Technology and Instruments, Guilin University of Electronic Technology, Guilin, Guangxi, 541004, China
| | - Qiang Liu
- School of Life and Environmental Sciences, Guangxi Key Laboratory of Automatic Detecting Technology and Instruments, Guilin University of Electronic Technology, Guilin, Guangxi, 541004, China
| | - Xing Liu
- School of Life and Environmental Sciences, Guangxi Key Laboratory of Automatic Detecting Technology and Instruments, Guilin University of Electronic Technology, Guilin, Guangxi, 541004, China
| | - Yan Li
- School of Life and Environmental Sciences, Guangxi Key Laboratory of Automatic Detecting Technology and Instruments, Guilin University of Electronic Technology, Guilin, Guangxi, 541004, China
| | - Ying Liang
- School of Life and Environmental Sciences, Guangxi Key Laboratory of Automatic Detecting Technology and Instruments, Guilin University of Electronic Technology, Guilin, Guangxi, 541004, China.
| | - Min Zhang
- School of Life and Environmental Sciences, Guangxi Key Laboratory of Automatic Detecting Technology and Instruments, Guilin University of Electronic Technology, Guilin, Guangxi, 541004, China.
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9
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De Silva M, Opallage PM, Dunn RC. Direct detection of inorganic ions and underivatized amino acids in seconds using high-speed capillary electrophoresis coupled with back-scatter interferometry. ANALYTICAL METHODS : ADVANCING METHODS AND APPLICATIONS 2021; 13:1340-1348. [PMID: 33491683 DOI: 10.1039/d0ay02218g] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
High speed capillary electrophoresis (HSCE) combined with refractive index (RI) detection is developed for the rapid separation and detection of inorganic ions and amino acids. A mixture of three inorganic ions (K+, Na+, Li+) and eight amino acids (Lys, Arg, Ala, Gly, Val, Thr, Trp, Asp) are detected using back scatter interferometry (BSI), without the need for chemical modifications or contrast. A thin-walled separation capillary (50 μm i.d. by 80 μm o.d.) helps mitigate Joule heating at the high field strengths required for rapid separations. This, combined with a short 8 cm length-to-detector (10 cm total length), enables separations on the seconds time scale. Using a background electrolyte (BGE) of 4 M acetic acid (pH 1.6) and a field strength of 900 V cm-1, all 11 analytes are separated in less than 40 s. Moreover, peaks in the BSI signal arising from the sample injection and EOF, enable electrophoretic mobilities to readily be obtained from apparent mobilities. This leads to excellent repeatability, with analyte electrophoretic mobilities varying from 0.39 to 1.56 % RSD over eight consecutive separations. The universal detection of inorganic ions and amino acids without prior chemical modification or additives in the BGE is an advantage of refractive index detection. A disadvantage arises from modest detection limits. Here, however, we show that submicromolar detection is possible with careful thermostatting of the thin separation capillary. A series of electropherograms are used to quantify arginine concentrations from 700 nM to 500 μM, using 50 μM Li+ as an internal standard. The resulting calibration curve leads to a calculated LOD of 376 nM and a LOQ of 1.76 μM. Diagnostically relevant amino acid panels are also separated, illustrating the potential for future applications in neurodegenerative and metabolic disease diagnostics. HSCE combined with BSI detection, therefore, is shown to be a rapid, sensitive, and universal approach for analyzing sample mixtures.
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Affiliation(s)
- Miyuru De Silva
- Ralph N. Adams Institute for Bioanalytical Chemistry, University of Kansas, 2030 Becker Drive, Lawrence, KS 66047, USA.
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10
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Hu Q, Guo R, Zhang L, Liu Q, Cai S, Lin W. A novel fluorescent probe for rapid detection of sulfur dioxide in living cells. LUMINESCENCE 2021; 36:1006-1012. [PMID: 33571398 DOI: 10.1002/bio.4026] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2021] [Revised: 02/01/2021] [Accepted: 02/04/2021] [Indexed: 11/06/2022]
Abstract
Sulfur dioxide is one of the reactive sulfur species, which has significant physiological functions in cells. Some physiological processes are closely related to SO2 in organisms, and the high concentration of SO2 in living cells can cause many diseases. In order to investigate the unique function of SO2 at the subcellular level, developing a molecular tool which could detect of SO2 within organelles is imperative. Hence, we developed a cationic dye named HQ-SO2 as a new fluorescent probe to specifically monitor SO2 , which was easy to obtain through one-step reaction. It took Michael addition reaction as the mechanism of reaction for detection of SO2 . In addition, this probe showed a series of highly favorable properties such as rapid response rate, low cytotoxicity, high selectivity, low detection limit, and good photostability, which enabled the probe to track SO2 in living cells.
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Affiliation(s)
- Qian Hu
- Guangxi Key Laboratory of Electrochemical Energy Materials, Institute of Optical Materials and Chemical Biology, School of Chemistry and Chemical Engineering, Guangxi University, Nanning, Guangxi, China
| | - Rui Guo
- Guangxi Key Laboratory of Electrochemical Energy Materials, Institute of Optical Materials and Chemical Biology, School of Chemistry and Chemical Engineering, Guangxi University, Nanning, Guangxi, China
| | - Liang Zhang
- Guangxi Key Laboratory of Electrochemical Energy Materials, Institute of Optical Materials and Chemical Biology, School of Chemistry and Chemical Engineering, Guangxi University, Nanning, Guangxi, China
| | - Qing Liu
- Guangxi Key Laboratory of Electrochemical Energy Materials, Institute of Optical Materials and Chemical Biology, School of Chemistry and Chemical Engineering, Guangxi University, Nanning, Guangxi, China
| | - Shushun Cai
- Guangxi Key Laboratory of Electrochemical Energy Materials, Institute of Optical Materials and Chemical Biology, School of Chemistry and Chemical Engineering, Guangxi University, Nanning, Guangxi, China
| | - Weiying Lin
- Guangxi Key Laboratory of Electrochemical Energy Materials, Institute of Optical Materials and Chemical Biology, School of Chemistry and Chemical Engineering, Guangxi University, Nanning, Guangxi, China
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Davis JJ, Foster SW, Grinias JP. Low-cost and open-source strategies for chemical separations. J Chromatogr A 2021; 1638:461820. [PMID: 33453654 PMCID: PMC7870555 DOI: 10.1016/j.chroma.2020.461820] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 12/12/2020] [Accepted: 12/14/2020] [Indexed: 12/18/2022]
Abstract
In recent years, a trend toward utilizing open access resources for laboratory research has begun. Open-source design strategies for scientific hardware rely upon the use of widely available parts, especially those that can be directly printed using additive manufacturing techniques and electronic components that can be connected to low-cost microcontrollers. Open-source software eliminates the need for expensive commercial licenses and provides the opportunity to design programs for specific needs. In this review, the impact of the "open-source movement" within the field of chemical separations is described, primarily through a comprehensive look at research in this area over the past five years. Topics that are covered include general laboratory equipment, sample preparation techniques, separations-based analysis, detection strategies, electronic system control, and software for data processing. Remaining hurdles and possible opportunities for further adoption of open-source approaches in the context of these separations-related topics are also discussed.
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Affiliation(s)
- Joshua J Davis
- Department of Chemistry & Biochemistry, Rowan University, Glassboro, NJ 08028, United States
| | - Samuel W Foster
- Department of Chemistry & Biochemistry, Rowan University, Glassboro, NJ 08028, United States
| | - James P Grinias
- Department of Chemistry & Biochemistry, Rowan University, Glassboro, NJ 08028, United States.
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