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Facile and highly efficient three-phase single drop microextraction in-line coupled with capillary electrophoresis. J Chromatogr A 2021; 1655:462520. [PMID: 34517164 DOI: 10.1016/j.chroma.2021.462520] [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: 05/29/2021] [Revised: 08/26/2021] [Accepted: 08/29/2021] [Indexed: 11/23/2022]
Abstract
A high-performance version of in-line, three-phase direct immersion-single drop microextraction (DI-SDME) coupled with capillary electrophoresis (CE) was demonstrated using a commercial CE instrument, and all the major and minor details were described to provide an easy-to-follow and user-friendly protocol. The excellent sample cleanup and enrichment power of this method was demonstrated with nonsteroidal anti-inflammatory drugs (NSAIDs) in human urine. The only preparation of urine samples was the addition of HCl to acidify the urine sample to pH 2. The acidic NSAIDs in the acidified urine sample were extracted into a basic acceptor drop covered with a thin organic layer attached to the inlet tip of a capillary immersed in the sample. A simple but powerful DI-SDME-CE method could be carried out automatically without any modification of the existing CE instrument. For improved performance, sample agitation and heating were employed by installing a microstirrer and a thermostating jacket in the sample tray. With 10 min of DI-SDME at 35°C with stirring, NSAIDs such as ketoprofen, ibuprofen, and naproxen in urine were enriched 340-970-fold with intraday and interday RSDs of 0.8-2.4% and 1.1-3.6%, respectively. The LODs obtained with in-line coupled CE/UV were 10-50 nM (2-10 µg/L). The performance of DI-SDME-CE/UV was also demonstrated by determining the naproxen level in human urine collected 24 h after taking a single oral dose of the drug. The spike recovery of naproxen from a single-point standard addition to the urine sample was 80%. Our high-performance three-phase DI-SDME-CE method is quite promising for the analysis of ionizable trace analytes in a complex sample matrix.
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Abstract
The current clinical and forensic toxicological analysis of body fluids requires a modern approach to sample preparation characterized by high selectivity and enrichment capability, suitability for micro-samples, simplicity and speed, and the possibility of automation and miniaturization, as well as the use of small amounts of reagents, especially toxic solvents. Most of the abovementioned features may be realized using so-called microextraction techniques which cover liquid-phase techniques (e.g., single-drop microextraction, SDME; dispersive liquid–liquid microextraction, DLLME; hollow-fiber liquid-phase microextraction, HF-LPME) and solid-phase extraction techniques (solid-phase microextraction, SPME; microextraction in packed syringes, MEPS; disposable pipette tip extraction, DPX; stir bar sorption extraction, SBSE). Some other extraction methodologies like dispersive solid-phase extraction (d-SPE) or magnetic solid-phase extraction (MSPE) can also be easily miniaturized. This review briefly describes and characterizes the abovementioned extraction methods, and then presents their current applications to the preparation of body fluids analyzed for bioactive compounds in combination with appropriate analytical methods, mainly chromatographic and related techniques. The perspectives of the analytical area we are interested in are also indicated.
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3
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Yue ME, Lin Q, Xu J, Jiang TF. Ionic liquid-based headspace in-tube liquid-phase microextraction coupled with capillary electrophoresis for sensitive detection of phenols. Electrophoresis 2018; 39:1771-1776. [PMID: 29683521 DOI: 10.1002/elps.201800068] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Revised: 04/07/2018] [Accepted: 04/15/2018] [Indexed: 12/20/2022]
Abstract
An ionic liquid-based headspace in-tube liquid-phase microextraction (IL-HS-ITLPME) in-line coupled with capillary electrophoresis (CE) is proposed. The method is capable of quantifying trace amounts of phenols in environmental water samples. In the newly developed method, simply by placing a capillary injected with IL in the HS above the aqueous sample, volatile phenols were extracted into the IL acceptor phase in the capillary. After extraction, electrophoresis of the phenols in the capillary was carried out. Extraction parameters such as the extraction time, extraction temperature, ionic strength, volume of the sample solution and IL types were systematically investigated. Under the optimized conditions, enrichment factors for four phenols were from 1510 to 1985. The proposed method provided a good linearity, low limits of detection (below 5.0 ng mL-1 ), and good repeatability of the extractions (RSDs below 6.7%, n = 6). This method was then utilized to analyze two real environmental samples of Xiaoxi Lake and tap water, obtaining acceptable recoveries and precisions. Compared with the usual HS-ITLPME for CE, IL-HS-ITLPME-CE is a simple, low-cost, fast and environmentally friendly pre-concentration technique. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Mei-E Yue
- Key Laboratory of Sensor Analysis of Tumor Marker, Ministry of Education, College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao, China
| | - Qiaoyan Lin
- Key Laboratory of Sensor Analysis of Tumor Marker, Ministry of Education, College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao, China
| | - Jie Xu
- Key Laboratory of Sensor Analysis of Tumor Marker, Ministry of Education, College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao, China
| | - Ting-Fu Jiang
- School of Medicine and Pharmacy, Ocean University of China, Qingdao, P. R. China
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4
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Ocaña-González JA, Fernández-Torres R, Bello-López MÁ, Ramos-Payán M. New developments in microextraction techniques in bioanalysis. A review. Anal Chim Acta 2016; 905:8-23. [DOI: 10.1016/j.aca.2015.10.041] [Citation(s) in RCA: 128] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 10/08/2015] [Accepted: 10/28/2015] [Indexed: 12/21/2022]
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5
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Electrophoretic concentration and sweeping-micellar electrokinetic chromatography analysis of cationic drugs in water samples. J Chromatogr A 2015; 1401:84-8. [DOI: 10.1016/j.chroma.2015.05.018] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Revised: 05/08/2015] [Accepted: 05/08/2015] [Indexed: 11/18/2022]
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6
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Springer VH, Lista AG. In-line coupled single drop liquid-liquid-liquid microextraction with capillary electrophoresis for determining fluoroquinolones in water samples. Electrophoresis 2015; 36:1572-9. [DOI: 10.1002/elps.201400602] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Revised: 03/02/2015] [Accepted: 03/03/2015] [Indexed: 11/06/2022]
Affiliation(s)
- Valeria H. Springer
- Analytical Chemistry Section; INQUISUR (UNS-CONICET); Bahía Blanca Buenos Aires Argentina
| | - Adriana G. Lista
- Analytical Chemistry Section; INQUISUR (UNS-CONICET); Bahía Blanca Buenos Aires Argentina
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7
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Jahan S, Xie H, Zhong R, Yan J, Xiao H, Fan L, Cao C. A highly efficient three-phase single drop microextraction technique for sample preconcentration. Analyst 2015; 140:3193-200. [DOI: 10.1039/c4an02324b] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A highly efficient three-phase single drop microextraction method is presented by using an organic–aqueous compound droplet and a microdevice.
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Affiliation(s)
- Sharmin Jahan
- Laboratory of Analytical Biochemistry and Bio-separation
- State Key Laboratory of Microbial Metabolism
- School of Life Science and Biotechnology
- Shanghai Jiao Tong University
- Shanghai
| | - Haiyang Xie
- Laboratory of Analytical Biochemistry and Bio-separation
- State Key Laboratory of Microbial Metabolism
- School of Life Science and Biotechnology
- Shanghai Jiao Tong University
- Shanghai
| | - Ran Zhong
- Laboratory of Analytical Biochemistry and Bio-separation
- State Key Laboratory of Microbial Metabolism
- School of Life Science and Biotechnology
- Shanghai Jiao Tong University
- Shanghai
| | - Jian Yan
- Institute of Refrigeration and Cryogenics
- School of Mechanical Engineering
- Shanghai Jiao Tong University
- Shanghai 200240
- China
| | - Hua Xiao
- Laboratory of Analytical Biochemistry and Bio-separation
- State Key Laboratory of Microbial Metabolism
- School of Life Science and Biotechnology
- Shanghai Jiao Tong University
- Shanghai
| | - Liuyin Fan
- Laboratory of Analytical Biochemistry and Bio-separation
- State Key Laboratory of Microbial Metabolism
- School of Life Science and Biotechnology
- Shanghai Jiao Tong University
- Shanghai
| | - Chengxi Cao
- Laboratory of Analytical Biochemistry and Bio-separation
- State Key Laboratory of Microbial Metabolism
- School of Life Science and Biotechnology
- Shanghai Jiao Tong University
- Shanghai
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8
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Yan Y, Chen X, Hu S, Bai X. Applications of liquid-phase microextraction techniques in natural product analysis: A review. J Chromatogr A 2014; 1368:1-17. [DOI: 10.1016/j.chroma.2014.09.068] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2014] [Revised: 09/24/2014] [Accepted: 09/25/2014] [Indexed: 11/27/2022]
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9
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The current role of on-line extraction approaches in clinical and forensic toxicology. Bioanalysis 2014; 6:2261-74. [DOI: 10.4155/bio.14.179] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
In today's clinical and forensic toxicological laboratories, automation is of interest because of its ability to optimize processes, to reduce manual workload and handling errors and to minimize exposition to potentially infectious samples. Extraction is usually the most time-consuming step; therefore, automation of this step is reasonable. Currently, from the field of clinical and forensic toxicology, methods using the following on-line extraction techniques have been published: on-line solid-phase extraction, turbulent flow chromatography, solid-phase microextraction, microextraction by packed sorbent, single-drop microextraction and on-line desorption of dried blood spots. Most of these published methods are either single-analyte or multicomponent procedures; methods intended for systematic toxicological analysis are relatively scarce. However, the use of on-line extraction will certainly increase in the near future.
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Novel and simple headspace in-tube microextraction coupled with capillary electrophoresis. J Chromatogr A 2014; 1346:117-22. [PMID: 24811149 DOI: 10.1016/j.chroma.2014.04.052] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2014] [Revised: 04/16/2014] [Accepted: 04/17/2014] [Indexed: 11/21/2022]
Abstract
In liquid phase microextraction, high enrichment factors can be obtained using an acceptor phase of small volume. By hanging an acceptor drop at the separation capillary tip, single drop microextraction (SDME) can be in-line coupled with capillary electrophoresis (CE). The small surface-to-volume ratio of the drop enables high enrichment factors to be obtained in a short time. One practical issue in SDME is how to keep the drop attached to the capillary stable. Here, we present novel but extremely simple in-tube microextraction (ITME) using the liquid inside the capillary as an acceptor phase, without forming a drop at the capillary tip. As a first example, ITME has been combined with headspace (HS) extraction. Simply by placing a capillary filled with a basic run buffer in the HS above an acidic donor solution, volatile acidic analytes were extracted into the acceptor phase in the capillary. After extraction, electrophoresis of the extracts in the capillary was carried out. Owing to the robust nature of the acceptor phase, the extraction temperature and time ranges of HS-ITME can be extended significantly, compared to HS-SDME. The enrichment factors for chlorophenols in a standard solution were up to 1100 under an optimal HS-ITME condition of 80°C for 15min and the limits of detections (LODs) obtained by monitoring the absorbance at 214nm were about 4nM. The whole procedures of HS-ITME-CE were carried out automatically using built-in programs of a commercial CE instrument.
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Abstract
AbstractLiquid-based micro-extraction is a novel “green” sample preparation technique using micro-litre levels of organic solvent to extract target analytes from various sample matrices for subsequent instrumental analysis. This technique developed rapidly from its introduction in the mid-1990s. Micro-extraction methods can be conveniently combined with a wide selection of instruments commonly used in a chemical laboratory; they significantly reduce analysis time and costs of solvents’ use and waste disposal. This review focuses on recent advances in several liquid-based micro-extraction methods, including single-drop micro-extraction, hollow fibre-liquid phase micro-extraction, and dispersive liquid-liquid micro-extraction. Examples of application of these methods to environmental, food, and biomedical analysis are listed.
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Determination of Anilines and Toluidines in Water by Salt-Assisted Dispersive Liquid–Liquid Microextraction Combined with GC-FID. Chromatographia 2013. [DOI: 10.1007/s10337-013-2559-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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13
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Dziomba S, Belka M, Kowalski P, Plenis A, Bączek T. The advances of electromigration techniques applied for alkaloid analysis. Biomed Chromatogr 2013; 27:1312-38. [DOI: 10.1002/bmc.2967] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Revised: 05/16/2013] [Accepted: 05/16/2013] [Indexed: 11/09/2022]
Affiliation(s)
- Szymon Dziomba
- Department of Pharmaceutical Chemistry; Medical University of Gdańsk; Hallera 107; 80-416; Gdańsk; Poland
| | - Mariusz Belka
- Department of Pharmaceutical Chemistry; Medical University of Gdańsk; Hallera 107; 80-416; Gdańsk; Poland
| | - Piotr Kowalski
- Department of Pharmaceutical Chemistry; Medical University of Gdańsk; Hallera 107; 80-416; Gdańsk; Poland
| | - Alina Plenis
- Department of Pharmaceutical Chemistry; Medical University of Gdańsk; Hallera 107; 80-416; Gdańsk; Poland
| | - Tomasz Bączek
- Department of Pharmaceutical Chemistry; Medical University of Gdańsk; Hallera 107; 80-416; Gdańsk; Poland
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14
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Breadmore MC, Shallan AI, Rabanes HR, Gstoettenmayr D, Abdul Keyon AS, Gaspar A, Dawod M, Quirino JP. Recent advances in enhancing the sensitivity of electrophoresis and electrochromatography in capillaries and microchips (2010-2012). Electrophoresis 2013; 34:29-54. [PMID: 23161056 DOI: 10.1002/elps.201200396] [Citation(s) in RCA: 124] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2012] [Revised: 09/03/2012] [Accepted: 09/04/2012] [Indexed: 12/21/2022]
Abstract
CE has been alive for over two decades now, yet its sensitivity is still regarded as being inferior to that of more traditional methods of separation such as HPLC. As such, it is unsurprising that overcoming this issue still generates much scientific interest. This review continues to update this series of reviews, first published in Electrophoresis in 2007, with updates published in 2009 and 2011 and covers material published through to June 2012. It includes developments in the field of stacking, covering all methods from field amplified sample stacking and large volume sample stacking, through to isotachophoresis, dynamic pH junction and sweeping. Attention is also given to online or inline extraction methods that have been used for electrophoresis.
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Affiliation(s)
- Michael C Breadmore
- Australian Centre for Research on Separation Science, School of Chemistry, University of Tasmania, Hobart, Tasmania, Australia.
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15
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Us MF, Alshana U, Lubbad I, Göğer NG, Ertaş N. Dispersive liquid-liquid microextraction based on solidification of floating organic drop combined with field-amplified sample injection in capillary electrophoresis for the determination of beta(2)-agonists in bovine urine. Electrophoresis 2013; 34:854-61. [DOI: 10.1002/elps.201200348] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Revised: 10/23/2012] [Accepted: 11/21/2012] [Indexed: 11/07/2022]
Affiliation(s)
| | - Usama Alshana
- Department of Analytical Chemistry; Faculty of Pharmacy; Gazi University; Ankara; Turkey
| | - Ibrahim Lubbad
- Department of Analytical Chemistry; Faculty of Pharmacy; Gazi University; Ankara; Turkey
| | - Nilgün G. Göğer
- Department of Analytical Chemistry; Faculty of Pharmacy; Gazi University; Ankara; Turkey
| | - Nusret Ertaş
- Department of Analytical Chemistry; Faculty of Pharmacy; Gazi University; Ankara; Turkey
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16
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Cheng K, Choi K, Kim J, Sung IH, Chung DS. Sensitive arsenic analysis by carrier-mediated counter-transport single drop microextraction coupled with capillary electrophoresis. Microchem J 2013. [DOI: 10.1016/j.microc.2012.07.005] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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17
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Silva M. Micellar electrokinetic chromatography: A review of methodological and instrumental innovations focusing on practical aspects. Electrophoresis 2012; 34:141-58. [DOI: 10.1002/elps.201200349] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Revised: 07/25/2012] [Accepted: 07/25/2012] [Indexed: 12/20/2022]
Affiliation(s)
- Manuel Silva
- Department of Analytical Chemistry, Rabanales Campus; University of Cordoba; Cordoba; Spain
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Šlampová A, Malá Z, Pantůčková P, Gebauer P, Boček P. Contemporary sample stacking in analytical electrophoresis. Electrophoresis 2012; 34:3-18. [PMID: 23161176 DOI: 10.1002/elps.201200346] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Revised: 07/20/2012] [Accepted: 07/20/2012] [Indexed: 12/29/2022]
Abstract
Sample stacking is a term denoting a multifarious class of methods and their names that are used daily in CE for online concentration of diluted samples to enhance separation efficiency and sensitivity of analyses. The essence of these methods is that analytes present at low concentrations in a large injected sample zone are concentrated into a short and sharp zone (stack) in the separation capillary. Then the stacked analytes are separated and detected. Regardless of the diversity of the stacking electromigration methods, one can distinguish four main principles that form the bases of nearly all of them: (i) Kohlrausch adjustment of concentrations, (ii) pH step, (iii) micellar methods, and (iv) transient ITP. This contribution is a continuation of our previous reviews on the topic and brings an overview of papers published during 2010-2012 and relevant to the mentioned principles (except the last one which is covered by another review in this issue).
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Affiliation(s)
- Andrea Šlampová
- Institute of Analytical Chemistry of the Academy of Sciences of the Czech Republic, Brno, Czech Republic
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Kohler I, Schappler J, Rudaz S. Microextraction techniques combined with capillary electrophoresis in bioanalysis. Anal Bioanal Chem 2012; 405:125-41. [PMID: 22965532 DOI: 10.1007/s00216-012-6367-y] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2012] [Revised: 08/14/2012] [Accepted: 08/19/2012] [Indexed: 11/28/2022]
Abstract
Over the past two decades, many environmentally sustainable sample-preparation techniques have been proposed, with the objective of reducing the use of toxic organic solvents or substituting these with environmentally friendly alternatives. Microextraction techniques (MEs), in which only a small amount of organic solvent is used, have several advantages, including reduced sample volume, analysis time, and operating costs. Thus, MEs are well adapted in bioanalysis, in which sample preparation is mandatory because of the complexity of a sample that is available in small quantities (mL or even μL only). Capillary electrophoresis (CE) is a powerful and efficient separation technique in which no organic solvents are required for analysis. Combination of CE with MEs is regarded as a very attractive environmentally sustainable analytical tool, and numerous applications have been reported over the last few decades for bioanalysis of low-molecular-weight compounds or for peptide analysis. In this paper we review the use of MEs combined with CE in bioanalysis. The review is divided into two sections: liquid and solid-based MEs. A brief practical and theoretical description of each ME is given, and the techniques are illustrated by relevant applications.
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Affiliation(s)
- Isabelle Kohler
- School of Pharmaceutical Sciences, University of Geneva, University of Lausanne, Bd d'Yvoy 20, 1211 Geneva 4, Switzerland
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Vallecillos L, Pocurull E, Borrull F. Fully automated ionic liquid-based headspace single drop microextraction coupled to GC–MS/MS to determine musk fragrances in environmental water samples. Talanta 2012; 99:824-32. [DOI: 10.1016/j.talanta.2012.07.036] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2012] [Revised: 07/06/2012] [Accepted: 07/15/2012] [Indexed: 10/28/2022]
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Development, validation, and application of a liquid chromatography-tandem mass spectrometry method for the determination of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol in human hair. Anal Bioanal Chem 2012; 404:2259-66. [PMID: 22926132 DOI: 10.1007/s00216-012-6356-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2012] [Revised: 08/07/2012] [Accepted: 08/13/2012] [Indexed: 12/19/2022]
Abstract
The tobacco-specific nitrosamine metabolite 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) is a valuable biomarker for human exposure to the carcinogenic nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) in tobacco and tobacco smoke. In this work, an efficient and sensitive method for the analysis of NNAL in human hair was developed and validated. The hair sample was extracted by NaOH solution digestion, purified by C(18) solid-phase extraction (SPE) and molecularly imprinted solid-phase extraction, further enriched by reverse-phase ultrasound-assisted dispersive liquid-liquid microextraction (USA-DLLME) into 1.0 % aqueous formic acid, and finally analyzed by liquid chromatography-electrospray ionization tandem mass spectrometry. Good linearity was obtained in the range of 0.24-10.0 pg/mg hair with a correlation coefficient of 0.9982, when 150 mg hair was analyzed. The limit of detection and lower limit of quantification were 0.08 and 0.24 pg/mg hair, respectively. Accuracies determined from hair samples spiked with three different levels of NNAL ranged between 87.3 and 107.7 %. Intra- and inter-day relative standard deviations varied from 4.1 to 8.5 % and from 6.9 to 11.3 %, respectively. Under the optimized conditions, an enrichment factor of 20 was obtained. Finally, the developed method was applied for the analysis of NNAL in smokers' hair. The proposed sample preparation procedure combining selectivity of two-step SPE and enrichment of DLLME significantly improves the purification and enrichment of the analyte and should be useful to analyze NNAL in hair samples for cancer risk evaluation and cancer prevention in relation to exposure to the tobacco-specific carcinogen NNK.
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Single-drop microextraction as a powerful pretreatment tool for capillary electrophoresis: A review. Anal Chim Acta 2012; 739:14-24. [DOI: 10.1016/j.aca.2012.06.005] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2012] [Revised: 06/02/2012] [Accepted: 06/02/2012] [Indexed: 01/16/2023]
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23
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Jain A, Verma KK. Recent advances in applications of single-drop microextraction: A review. Anal Chim Acta 2011; 706:37-65. [DOI: 10.1016/j.aca.2011.08.022] [Citation(s) in RCA: 134] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2011] [Revised: 08/11/2011] [Accepted: 08/15/2011] [Indexed: 10/17/2022]
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