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Li Y, Ma X, Wang W, Yan S, Liu F, Chu K, Xu G, Smith ZJ. Improving the limit of detection in portable luminescent assay readers through smart optical design. JOURNAL OF BIOPHOTONICS 2020; 13:e201900241. [PMID: 31602762 DOI: 10.1002/jbio.201900241] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 10/07/2019] [Accepted: 10/09/2019] [Indexed: 06/10/2023]
Abstract
Critical biomarkers of disease are increasingly being detected by point-of-care assays. Chemiluminescence (CL) and electrochemiluminescence (ECL) are often used in such assays due to their convenience and that they do not require light sources or other components that could complicate or add cost to the system. Reports of these assays often include readers built on a cellphone platform or constructed from low-cost components. However, the impact the optical design has on the limit of detection (LOD) in these systems remains unexamined. Here, we report a theoretical rubric to evaluate different optical designs in terms of maximizing the use of photons emitted from a CL or ECL assay to improve the LOD. We demonstrate that the majority of cellphone designs reported in the literature are not optimized, in part due to misunderstandings of the optical tradeoffs in collection systems, and in part due to limitations imposed on the designs arising from the use of a mobile phone with a very small lens aperture. Based on the theoretical rubric, we design a new portable reader built using off-the-shelf condenser optics, and demonstrate a nearly 10× performance enhancement compared to prior reports on an ECL assays running on a portable chip.
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Affiliation(s)
- Yaning Li
- University of Science and Technology of China, Department of Precision Machinery and Precision Instrumentation, Hefei, Anhui, China
- Key Laboratory of Precision Scientific Instrumentation of Anhui Higher Education Institutes, University of Science and Technology of China, Hefei, Anhui, China
| | - Xiangui Ma
- A State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin, China
- University of Science and Technology of China, School of Applied Chemistry and Engineering, Hefei, Anhui, China
| | - Wenhe Wang
- A State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin, China
- University of Science and Technology of China, School of Applied Chemistry and Engineering, Hefei, Anhui, China
| | - Shaojie Yan
- University of Science and Technology of China, Department of Precision Machinery and Precision Instrumentation, Hefei, Anhui, China
- Key Laboratory of Precision Scientific Instrumentation of Anhui Higher Education Institutes, University of Science and Technology of China, Hefei, Anhui, China
| | - Fangshuo Liu
- A State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin, China
- University of Science and Technology of China, School of Applied Chemistry and Engineering, Hefei, Anhui, China
| | - Kaiqin Chu
- University of Science and Technology of China, Department of Precision Machinery and Precision Instrumentation, Hefei, Anhui, China
- Key Laboratory of Precision Scientific Instrumentation of Anhui Higher Education Institutes, University of Science and Technology of China, Hefei, Anhui, China
- Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui, China
| | - Guobao Xu
- A State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin, China
- University of Science and Technology of China, School of Applied Chemistry and Engineering, Hefei, Anhui, China
| | - Zachary J Smith
- University of Science and Technology of China, Department of Precision Machinery and Precision Instrumentation, Hefei, Anhui, China
- Key Laboratory of Precision Scientific Instrumentation of Anhui Higher Education Institutes, University of Science and Technology of China, Hefei, Anhui, China
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Deng B, Shi A, Kang Y, Li L. Determination of metformin hydrochloride using precolumn derivatization with acetaldehyde and capillary electrophoresis coupled with electrochemiluminescence. LUMINESCENCE 2011; 26:592-7. [PMID: 21374792 DOI: 10.1002/bio.1276] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2010] [Revised: 10/26/2010] [Accepted: 12/19/2010] [Indexed: 01/24/2023]
Abstract
A novel method was developed using capillary electrophoresis (CE) coupled with tris(2,2'-bipyridyl)ruthenium(II) electrogenerated chemiluminescence (ECL) for highly sensitive detection of metformin hydrochloride (MH) derivatizatized with acetaldehyde. The precolumn derivatization of MH with acetaldehyde was performed in phosphate buffer solution (0.3 mol/L, pH 7.5) at room temperature for 120 min. The effects of acetaldehyde concentration, buffer pH, electrokinetic voltage and injection time were investigated. Under optimized detection conditions, the MH ECL detection sensitivity was more than 120 times that without derivatization. The linear concentration range for MH was 0.001-15.00 μg/mL (with a correlation coefficient of 0.9992). The detection limit was 0.31 ng/mL with a signal:noise ratio of 3. The recoveries of MH in human urine were in the range 98.50-99.72%. Copyright © 2011 John Wiley & Sons, Ltd.
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Affiliation(s)
- Biyang Deng
- Key Laboratory for Chemistry and Molecular Engineering of Medicinal Resources, Guangxi Normal University, Guilin, People's Republic of China.
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Zhang X, Xuan Y, Sun A, Lv Y, Hou X. Simultaneous determination of isoniazid andp-aminosalicylic acid by capillary electrophoresis using chemiluminescence detection. LUMINESCENCE 2009; 24:243-9. [DOI: 10.1002/bio.1107] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Fu GN, He YZ, Wang L, Wang XK. Determination of amino acids in tobacco samples by capillary electrophoresis/indirect absorbance detection with isolation of the electrolysis compartment and p-Aminobenzoic acid as a background electrolyte. ANAL SCI 2006; 22:883-7. [PMID: 16772690 DOI: 10.2116/analsci.22.883] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2005] [Accepted: 02/28/2006] [Indexed: 11/23/2022]
Abstract
A fast, convenient and sensitive method of capillary zone electrophoresis (CZE) and indirect UV detection was proposed for the determination of 16 amino acids. p-Aminobenzoic acid (PAB) was selected as a background electrolyte (BGE). An isolated cell included a BGE buffer part and an electrode buffer one, which were jointed with a glass frit. The isolated cell can prevent PAB from the electrode reaction and improve the stability of the detection baseline. The separation conditions of amino acids were investigated, such as different BGEs, BGE concentration, buffer pH and electroosmotic flow (EOF) modifiers. Under the selected separation conditions, 14 amino acid peaks could be separated in 12 min. The detection limits of the amino acids were in the range of 1.7 - 4.5 micromol/L. The isolated cell is suitable for reagents reacting on the electrodes in capillary electrophoresis. The proposed method has been successfully applied to the determination of the amino acids in tobacco samples.
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Affiliation(s)
- Guo-Ni Fu
- Department of Chemistry, University of Science and Technology of China, Hefei, Anhui, P. R. China
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Li J, Yan Q, Gao Y, Ju H. Electrogenerated Chemiluminescence Detection of Amino Acids Based on Precolumn Derivatization Coupled with Capillary Electrophoresis Separation. Anal Chem 2006; 78:2694-9. [PMID: 16615781 DOI: 10.1021/ac052092m] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A novel method for highly sensitive detection of primary and secondary amino acids with selective derivatization using acetaldehyde as a new derivatization reagent was proposed by capillary electrophoresis (CE) coupled with electrogenerated chemiluminescence (ECL) of tris(2,2'-bipyridine)ruthenium(II). The precolumn derivatization of these amino acids with acetaldehyde was performed in aqueous solution at room temperature for 1 h. Upon optimized derivatization, the ECL intensities and detection sensitivities of the amino acids were significantly enhanced by 20-70 times. Using four amino acids, arginine, proline, valine, and leucine, as model compounds, their derivatives could be completely separated by CE and sensitively detected by ECL within 22 min. The linear ranges were 0.5-100 microM for arginine and proline and 5-1000 microM for valine and leucine with the detection limits of 1 x 10(-7) (0.5 fmol, arginine), 8 x 10(-8) (0.4 fmol, proline), 1 x 10(-6) (5 fmol, valine), and 1.6 x 10(-6) M (8 fmol, leucine) at a signal-to-noise ratio of 3. The derivatization reactions and ECL process of amino acids were also proposed based on in situ Fourier transform infrared and ultraviolet spectrometric analyses.
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Affiliation(s)
- Jianguo Li
- Key Laboratory of Analytical Chemistry for Life Science (Ministry of Education of China), Department of Chemistry, Nanjing University, Nanjing 210093, P. R. China
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Liu J, Cao W, Qiu H, Sun X, Yang X, Wang E. Determination of Sulpiride by Capillary Electrophoresis with End-Column Electrogenerated Chemiluminescence Detection. Clin Chem 2002. [DOI: 10.1093/clinchem/48.7.1049] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Abstract
Background: Capillary electrophoresis (CE) with tris(2,2′-bipyridyl)ruthenium(II) [Ru(bpy)32+]-electrogenerated chemiluminescence (ECL) detection is a promising method for clinical analysis. In this study, a method combining CE with Ru(bpy)32+ ECL (CE-ECL) detection that can be applied to amine-containing clinical species was developed, and the performance of CE-ECL as a quantitative method for determination of sulpiride in human plasma or urine was evaluated.
Methods: Sulpiride was separated by capillary zone electrophoresis in uncoated fused-silica capillaries [50 cm × 25 μm (i.d.)] filled with phosphate buffer (pH 8.0) and a driving voltage of +15 kV, with end-column Ru(bpy)32+ ECL detection. A platinum disc electrode was used as working electrode. Sulpiride in human plasma or urine samples (100 μL) was extracted by a double-step liquid-liquid extraction procedure, dried under nitrogen at 35 °C in a water bath, and reconstituted with 100 μL of filtered water. The extraction solvent was ethyl acetate–dichloromethane (5:1 by volume).
Results: Under optimum conditions (pH 8.0 phosphate buffer, injection for 6 s at 10 kV, and +1.2 V as detection potential), separation of sulpiride was accomplished within 4 min. The calibration curve was linear over a concentration range of 0.05–25.0 μmol/L, and the limit of detection was 2.9 × 10−8 mol/L for sulpiride. Intra- and interday CVs for ECL intensities were <6%. Extraction recoveries of sulpiride were 95.6–101% with CVs of 2.9–6.0%. The method was clinically validated for patient plasma and urine samples.
Conclusions: CE combined with Ru(bpy)32+ ECL is reproducible, precise, selective, and enables the analysis of sulpiride in human plasma and urine. It thus is of value for rapid and efficient analysis of amine-containing analytes of clinical interest.
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Affiliation(s)
- Jifeng Liu
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, People’s Republic of China
| | - Weidong Cao
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, People’s Republic of China
| | - Haibo Qiu
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, People’s Republic of China
| | - Xiuhua Sun
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, People’s Republic of China
| | - Xiurong Yang
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, People’s Republic of China
| | - Erkang Wang
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, People’s Republic of China
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Abstract
One of the weak points of capillary electrophoresis is the need to implement rigorously sample pretreatment because its great impact on the quality of the qualitative and quantitative results provided. One of the approaches to solve this problem is through the symbiosis of automatic continuous flow systems (CFSs) and capillary electrophoresis (CE). In this review a systematic approach to CFS-CE coupling is presented and discussed. The design of the corresponding interface depends on three factors, namely: (a) the characteristics of the CFS involved which can be non-chromatographic and chromatographic; (b) the type of CE equipment: laboratory-made or commercially available; and (c) the type of connection which can be in-line (on-capillary), on-line or mixed off/on-line. These are the basic criteria to qualify the hyphenation of CFS (solid-phase extraction, dialysis, gas diffusion, evaporation, direct leaching) with CE described so far and applied to determine a variety of analytes in many different types of samples. A critical discussion allows one to demonstrate that this symbiosis is an important topic in research and development, besides separation and detection, to consolidate CE as a routine analytical tool.
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Affiliation(s)
- M Valcárcel
- Analytical Chemistry Division, University of Córdoba, Spain.
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Hendrickson HP, Anderson P, Wang X, Pittman Z, Bobbitt DR. Compositional analysis of small peptides using capillary electrophoresis and Ru(bpy)33+-based chemiluminescence detection. Microchem J 2000. [DOI: 10.1016/s0026-265x(00)00052-7] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Abstract
Capillary electrophoresis interfaced with electrospray is a convenient technique for continuously transferring column effluent from capillary-to-planar format. Conditions are optimized to produce a narrow (approximately 20 microm) liquid filament (electrofilament), which is capable of depositing spatially focused bands with track widths that are routinely 100 microm. A fiber optic-based, laser-induced fluorescence cell is employed to monitor the separation on-column while the separated bands are deposited onto a moving substrate. The photodetection of deposited bands is accomplished by using either a charge-coupled device camera or a photomultiplier tube. Deterioration of on-column separation performance is observed when the electrofilament voltage is applied. Elevating the inlet of the capillary column, to provide hydrodynamic flow, restores separation performance. Substrate temperature and translational rates are optimized with respect to both off-column separation efficiency and signal intensity. Off-column separation efficiencies of 65 000 plates per meter were achieved. A linear dynamic range of 10(3) and a limit of detection of 10(-8) M were obtained for kiton red deposited onto a reversed phase thin-layer chromatography plate. To demonstrate the applicability of this technique to more complex separation solutions, a dye mixture was successfully separated and deposited with sodium dodecyl sulfate in the running buffer.
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Affiliation(s)
- G L DeVault
- Department of Chemistry, University of Tennessee, Knoxville 37996-1600, USA
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Hashimoto M, Tsukagoshi K, Nakajima R, Kondo K, Arai A. Microchip capillary electrophoresis using on-line chemiluminescence detection. J Chromatogr A 2000; 867:271-9. [PMID: 10670727 DOI: 10.1016/s0021-9673(99)01169-3] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Chemiluminescence detection was used in capillary electrophoresis integrated on a microchip. Quartz microchips have two main channels and four reservoirs. Dansyl-lysine and -glycine were separated and detected with bis[(2-(3,6,9-trioxadecanyloxycarbony)-4-nitrophenyl]oxalate as peroxyoxalate chemiluminescent reagent. These dansyl amino acids came into contact with the chemiluminescence reagent to produce visible light at the interface between the separation channel and chemiluminescence reagent-containing reservoir. The detection limit (S/N = 3) for dansyl-lysine was 1 x 10(-5) M, which corresponded to the very small mass detection limit of ca. 0.4 fmol. However, the concentration sensitivity in the present system was approximately two orders of magnitude lower than that in the conventional capillary electrophoresis-chemiluminescence detection system. The relative standard deviations of migration time and peak height for dansyl-lysine were 4.2 and 4.5%, respectively. A channel conditioning before every run and an appropriate control of voltages were needed for the reproducible results. The present system had advantages in rapid separation time (within 40 s), small (several 10 pI) and accurate sample injection method using a cross-shaped injector, and simplification and miniaturization of the detection device.
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Affiliation(s)
- M Hashimoto
- Department of Chemical Engineering and Materials Science, Faculty of Engineering, Doshisha University, Kyotanabe, Kyoto, Japan
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Abstract
Recent advances in the analysis of amino acids using capillary electrophoresis are addressed. This area of research continues to receive increased attention as is evident from the 62 references reviewed. This review discusses current detection strategies including UV absorbance, laser-induced fluorescence, electrochemical, and others. Separation methodologies for both derivatized and underivatized amino acids are reviewed. Both direct and indirect enantiomeric resolution of amino acids are addressed. Applications utilizing capillary electrophoresis for the analysis of amino acids are discussed. This review covers literature published in 1997 and 1998.
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Affiliation(s)
- J T Smith
- Department of Physical Sciences, Southeastern Oklahoma State University, Durant 74701-0609, USA.
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