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Characterization of linearly coupled capillaries with various inner diameters in the context of capillary electrophoresis. MONATSHEFTE FUR CHEMIE 2021. [DOI: 10.1007/s00706-021-02783-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
AbstractAs a result of continuous instrumental progress, capillary electrophoresis has become an established separation technique. However, the choice of the suitable capillary inner diameter is sometimes difficult due to different instrumental requirements concerning injection, separation, or detection. To overcome this problem, we assembled two capillaries with different inner diameters, meaning that the inner diameter of the capillary at the injection side was different from that at the detection side. Since this was a rather uncommon approach, we focused on the associated effects in this proof-of-concept study. For the experiments, a non-aqueous model system was used, consisting of an acetonitrile-based background electrolyte and the two ferrocene derivates, ferrocenemethanol and decamethylferrocene. Using capillary flow injection analysis hyphenated to capacitively coupled contactless conductivity detection, it could be shown that fragmented capillaries of the same inner diameter had slightly lower volume flow rates than non-fragmented capillaries. With non-aqueous capillary electrophoresis hyphenated to UV detection, it was found that the coupling of capillaries with different inner diameter had a much stronger effect on the capillary electrophoresis flow than combinations with the same inner diameter. Additionally, if the inner diameter of the second capillary was larger than the inner diameter of the first capillary, a higher theoretical plate number and an increased sensitivity were found. Furthermore, it was found that there was no significant peak tailing introduced by the coupling.
Graphic abstract
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Paiva RD, Mallmann AMMC, Santos JC, Kist TBL. Polyimide removal, cleaving, and fusion splicing of cylindrical and square fused silica capillaries for new separation and detection layouts in capillary electrophoresis and chromatography. J Sep Sci 2021; 44:2438-2448. [PMID: 33866676 DOI: 10.1002/jssc.202100215] [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: 03/13/2021] [Revised: 04/12/2021] [Accepted: 04/14/2021] [Indexed: 11/08/2022]
Abstract
Fusion splicing is an already mature technology used to join the ends of optical fibers in the telecommunication industry. However, there is a lack of reliable and well-described protocols to join the ends of fused silica microtubes or capillaries using fusion splicing. In this work, a step-by-step procedure is proposed and demonstrated to find the optimal operation conditions to splice the ends of fused silica capillaries by fusion. The two most appropriate and known technologies were tested and optimized: the microfurnace technique (or hot filament technique) and the electric arc technique. It is shown that both produce good splices when the capillaries are well cleaved. For this reason, the removal of the external coating, which is important for good cleavage, was also revised. The cleaving techniques were also compared among themselves. As a result, fusion splices of cylindric-to-cylindric, cylindric-to-square, and square-to-square capillaries are demonstrated. They have potential applications in new detection schemes and separation layouts in capillary electrophoresis, electrophoresis-based hydrodynamic concentrators, chromatography, cell sorters, and microfluidics in general.
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Affiliation(s)
- Raul Dias Paiva
- Department of Electrical Energy and Automation Engineering, EPUSP, University of São Paulo, Butantan, São Paulo, Brazil
| | - Ana Maria M C Mallmann
- Laboratory of Methods, Department of Biophysics, Institute of Biosciences, Federal University of Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil
| | - Josemir C Santos
- Department of Electrical Energy and Automation Engineering, EPUSP, University of São Paulo, Butantan, São Paulo, Brazil
| | - Tarso B Ledur Kist
- Laboratory of Methods, Department of Biophysics, Institute of Biosciences, Federal University of Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil
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Determination of orotic acid in human urine using a combination of two capillaries with different internal diameters. CHEMICAL PAPERS 2020. [DOI: 10.1007/s11696-020-01076-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Amorim TL, Duarte LM, Dos Santos HF, de Oliveira MAL. Screening method for simultaneous detection of elaidic and vaccenic trans fatty acid isomers by capillary zone electrophoresis. Anal Chim Acta 2019; 1048:212-220. [DOI: 10.1016/j.aca.2018.10.057] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Revised: 10/22/2018] [Accepted: 10/23/2018] [Indexed: 12/27/2022]
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Gao J, Wang J, Wu C, Hou F, Chang S, Wang Z, Pu Q, Guo D, Fu H. Fast screening of aflatoxins in dairy cattle feeds with CE-LIF method combined with preconcentration technique of vortex assisted low density solvent-microextraction. Electrophoresis 2018; 40:499-507. [PMID: 30467879 DOI: 10.1002/elps.201800339] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Revised: 10/21/2018] [Accepted: 11/14/2018] [Indexed: 12/29/2022]
Abstract
Aflatoxin contamination in agricultural products poses a great threat to humans and livestock. The aim of this study was to establish a simple, rapid, highly sensitive, and inexpensive method for the simultaneous detection of aflatoxin B1 , B2 , G1 , and G2 in agricultural products. We used a vortex assisted low density solvent-microextraction (VALDS-ME) technique for sample preconcentration and sample detection was achieved with a CE-LIF method. Aflatoxins were separated in an uncoated fused-silica capillary with the MEKC mode and were excited by a 355 nm UV laser to produce native fluorescence for detection. The obtained LOD and LOQ for the four aflatoxins were in the range of 0.002-0.075 and 0.007-0.300 μg/L, respectively, and the analysis time was within 6.5 min. Using the established method, aflatoxins were screened in naturally contaminated dairy cattle feed samples including alfalfa, bran, and corn kernel. The result shows that the alfalfa and bran samples were contaminated with aflatoxins to varying degrees. Compared with other analytical techniques for aflatoxin screening in agricultural products, this CE-LIF method combined with VALDS-ME preconcentration technique is simple, rapid, highly efficient, and inexpensive.
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Affiliation(s)
- Jing Gao
- State Key Laboratory of Grassland Agro-ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, Gansu, P. R. China
| | - Jing Wang
- State Key Laboratory of Grassland Agro-ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, Gansu, P. R. China
| | - Chengxin Wu
- College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, Gansu, P. R. China
| | - Fujiang Hou
- State Key Laboratory of Grassland Agro-ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, Gansu, P. R. China
| | - Shenghua Chang
- State Key Laboratory of Grassland Agro-ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, Gansu, P. R. China
| | - Zhaofeng Wang
- State Key Laboratory of Grassland Agro-ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, Gansu, P. R. China
| | - Qiaosheng Pu
- College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, Gansu, P. R. China
| | - Ding Guo
- State Key Laboratory of Grassland Agro-ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, Gansu, P. R. China
| | - Hua Fu
- State Key Laboratory of Grassland Agro-ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, Gansu, P. R. China
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