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Ferreira PS, Victorelli FD, Fonseca-Santos B, Chorilli M. A Review of Analytical Methods for p-Coumaric Acid in Plant-Based Products, Beverages, and Biological Matrices. Crit Rev Anal Chem 2018; 49:21-31. [PMID: 29757687 DOI: 10.1080/10408347.2018.1459173] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
p-Coumaric acid (p-CA), also known as 4-hydroxycinnamic acid, is a phenolic acid, which has been widely studied due to its beneficial effects against several diseases and its wide distribution in the plant kingdom. This phenolic compound can be found in the free form or conjugated with other molecules; therefore, its bioavailability and the pathways via which it is metabolized change according to its chemical structure. p-CA has potential pharmacological effects because it has high free radical scavenging, anti-inflammatory, antineoplastic, and antimicrobial activities, among other biological properties. It is therefore essential to choose the most appropriate and effective analytical method for qualitative and quantitative determination of p-CA in different matrices, such as plasma, urine, plant extracts, and drug delivery systems. The most-reported analytical method for this purpose is high-performance liquid chromatography, which is mostly coupled with some type of detectors, such as UV/Vis detector. However, other analytical techniques are also used to evaluate this compound. This review presents a summary of p-CA in terms of its chemical and pharmacokinetic properties, pharmacological effects, drug delivery systems, and the analytical methods described in the literature that are suitable for its quantification.
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Affiliation(s)
- Paula Scanavez Ferreira
- a São Paulo State University (UNESP), School of Pharmaceutical Sciences , Araraquara , São Paulo , Brazil
| | | | - Bruno Fonseca-Santos
- a São Paulo State University (UNESP), School of Pharmaceutical Sciences , Araraquara , São Paulo , Brazil
| | - Marlus Chorilli
- a São Paulo State University (UNESP), School of Pharmaceutical Sciences , Araraquara , São Paulo , Brazil
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Khani R, Rahmanian R, Motlagh NV. UV–Visible Spectrometry and Multivariate Calibration as a Rapid and Reliable Tool for Simultaneous Quantification of Ternary Mixture of Phenolic Acids in Fruit Juice Samples. FOOD ANAL METHOD 2015. [DOI: 10.1007/s12161-015-0287-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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3
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da Rosa Neng N, Sequeiros RCP, Florêncio Nogueira JM. Combining bar adsorptive microextraction with capillary electrophoresis-Application for the determination of phenolic acids in food matrices. Electrophoresis 2014; 35:2488-94. [DOI: 10.1002/elps.201400101] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2014] [Revised: 04/14/2014] [Accepted: 04/15/2014] [Indexed: 11/11/2022]
Affiliation(s)
- Nuno da Rosa Neng
- Chemistry and Biochemistry Department and Center of Chemistry and Biochemistry; Faculty of Sciences, University of Lisbon; Lisbon Portugal
| | - Rute C. P. Sequeiros
- Chemistry and Biochemistry Department and Center of Chemistry and Biochemistry; Faculty of Sciences, University of Lisbon; Lisbon Portugal
| | - José Manuel Florêncio Nogueira
- Chemistry and Biochemistry Department and Center of Chemistry and Biochemistry; Faculty of Sciences, University of Lisbon; Lisbon Portugal
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Khani R, Ghasemi JB, Shemirani F. Second-order data obtained by beta-cyclodextrin complexes: a novel approach for multicomponent analysis with three-way multivariate calibration methods. Talanta 2014; 128:254-62. [PMID: 25059157 DOI: 10.1016/j.talanta.2014.04.040] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2014] [Revised: 04/12/2014] [Accepted: 04/15/2014] [Indexed: 11/29/2022]
Abstract
This research reports the first application of β-cyclodextrin (β-CD) complexes as a new method for generation of three way data, combined with second-order calibration methods for quantification of a binary mixture of caffeic (CA) and vanillic (VA) acids, as model compounds in fruit juices samples. At first, the basic experimental parameters affecting the formation of inclusion complexes between target analytes and β-CD were investigated and optimized. Then under the optimum conditions, parallel factor analysis (PARAFAC) and bilinear least squares/residual bilinearization (BLLS/RBL) were applied for deconvolution of trilinear data to get spectral and concentration profiles of CA and VA as a function of β-CD concentrations. Due to severe concentration profile overlapping between CA and VA in β-CD concentration dimension, PARAFAC could not be successfully applied to the studied samples. So, BLLS/RBL performed better than PARAFAC. The resolution of the model compounds was possible due to differences in the spectral absorbance changes of the β-CD complexes signals of the investigated analytes, opening a new approach for second-order data generation. The proposed method was validated by comparison with a reference method based on high-performance liquid chromatography photodiode array detection (HPLC-PDA), and no significant differences were found between the reference values and the ones obtained with the proposed method. Such a chemometrics-based protocol may be a very promising tool for more analytical applications in real samples monitoring, due to its advantages of simplicity, rapidity, accuracy, sufficient spectral resolution and concentration prediction even in the presence of unknown interferents.
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Affiliation(s)
- Rouhollah Khani
- School of Chemistry, University College of Science, University of Tehran, PO Box 14155-6455, Tehran, Iran
| | - Jahan B Ghasemi
- Department of Chemistry, Faculty of Sciences, K.N. Toosi University of Technology, Tehran 16617, Iran.
| | - Farzaneh Shemirani
- School of Chemistry, University College of Science, University of Tehran, PO Box 14155-6455, Tehran, Iran
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Hsieh SY, Wang CC, Wu SM. Microemulsion electrokinetic chromatography for analysis of phthalates in soft drinks. Food Chem 2013; 141:3486-91. [PMID: 23993511 DOI: 10.1016/j.foodchem.2013.06.023] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2012] [Revised: 04/05/2013] [Accepted: 06/06/2013] [Indexed: 02/05/2023]
Abstract
Microemulsion electrokinetic chromatography (MEEKC) is proposed for analysis of di-n-butyl phthalate (DBP) and di-(2-ethylhexyl) phthalate (DEHP) in soft drinks. However, the instability of microemulsion is a critical issue. In this research, a novel material, Pluronic® F-127, which has the properties of polymer and surfactant, was added for stabilizing the microemulsion in the MEEKC system. Our data demonstrate that the presence of Pluronic® F-127 (0.05-0.30%) also helps enhance resolution of highly hydrophobic compounds, DBP and DEHP. The electrokinetic injection of sodium dodecyl sulphate (SDS) including sample (-10 kV, 20 s) was introduced in this MEEKC system and this yielded about 25-fold sensitivity enhancement compared with hydrodynamic injection (1 psi, 10 s). During method validation, calibration curves were linear (r≥0.99), within a range of 75-500 ng/mL for DBP and 150-1000 ng/mL for DEHP. As the precision and accuracy assays, absolute values of relative standard deviation (RSD) and relative error (RE) in intraday (n=3) and interday (n=5) observations were less than 4.93%. This method was further applied for analyzing six commercial soft drinks and one was found containing 453.67 ng/mL of DEHP. This method is considered feasible for serving as a tool for analysis of highly hydrophobic molecules.
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Affiliation(s)
- Sung-Yu Hsieh
- School of Pharmacy, College of Pharmacy, Kaohsiung Medical University, Taiwan
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Yang H, Ding Y, Cao J, Li P. Twenty-one years of microemulsion electrokinetic chromatography (1991-2012): A powerful analytical tool. Electrophoresis 2013; 34:1273-94. [DOI: 10.1002/elps.201200494] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2012] [Revised: 12/18/2012] [Accepted: 01/22/2013] [Indexed: 12/18/2022]
Affiliation(s)
- Hua Yang
- State Key Laboratory of Natural Medicines (China Pharmaceutical University); Nanjing; P. R. China
| | - Yao Ding
- State Key Laboratory of Natural Medicines (China Pharmaceutical University); Nanjing; P. R. China
| | - Jun Cao
- College of Material Chemistry and Chemical Engineering; Hangzhou Normal University; Hangzhou; P. R. China
| | - Ping Li
- State Key Laboratory of Natural Medicines (China Pharmaceutical University); Nanjing; P. R. China
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Dias FDS, Klassen A, Tavares MFM, David JM. Fast Determination of Phenolic Compounds in Brazilian Wines from Vale do São Francisco Region by CE. Chromatographia 2013. [DOI: 10.1007/s10337-013-2399-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Ma N, Wang P, Kong X, Shi R, Yuan Z, Wang C. Selective removal of caffeine from tea extracts using macroporous crosslinked polyvinyl alcohol adsorbents. J Sep Sci 2011; 35:36-44. [PMID: 22102370 DOI: 10.1002/jssc.201100598] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2011] [Revised: 09/27/2011] [Accepted: 09/27/2011] [Indexed: 11/06/2022]
Abstract
The hydrolysis reaction of ester groups in vinyl acetate (VAc) was used to introduce hydroxyl groups into the matrix of a macroporous adsorbent, which was itself prepared by free radical suspension copolymerization of triallyl isocyanurate (TAIC) and VAc. Therefore, the copolymerization incompatibility between the hydrophilic and the hydrophobic monomer was overcome successfully and the hydrophobic matrix of the polymeric adsorbent containing a polyvinyl alcohol (PVA) segment was obtained. Introduction of the PVA segment decreased the hydrophobic adsorption affinity of the adsorbent while producing the hydrogen-bonding interaction. When isolating the two active components, polyphenols (TPh) and caffeine (CAF), from green tea extracts, this polymeric adsorbent, namely poly(TAIC-co-VA), exhibited good adsorption selectivity towards TPh over CAF. The adsorption mechanism leading to this selectivity involved a hydrophobic interaction mechanism for CAF and multiple weak hydrophobic and hydrogen-bonding interactions for TPh. The adsorption thermodynamics for TPh on poly(TAIC-co-VA) were studied. The effects of adsorbent structure and gradient desorption conditions on isolation were investigated. The result showed that adsorbent, with 20% TAIC content, was able to efficiently remove CAF from different tea extracts with different ratios of TPh and CAF. Finally, almost no CAF was detected in the TPh fraction and the recovery of TPh was greater than 95%.
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Affiliation(s)
- Ning Ma
- Key Laboratory of Functional Polymer Materials of the Ministry of Education, Institute of Polymer Chemistry, Nankai University, Tianjin, P. R. China
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López MDMC, Vilariño JML, Rodríguez MVG, Losada LFB. Development, validation and application of Micellar Electrokinetic Capillary Chromatography method for routine analysis of catechins, quercetin and thymol in natural samples. Microchem J 2011. [DOI: 10.1016/j.microc.2011.06.023] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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10
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Huang HY, Liu WL, Singco B, Hsieh SH, Shih YH. On-line concentration sample stacking coupled with water-in-oil microemulsion electrokinetic chromatography. J Chromatogr A 2011; 1218:7663-9. [DOI: 10.1016/j.chroma.2011.05.091] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2011] [Revised: 04/28/2011] [Accepted: 05/26/2011] [Indexed: 02/06/2023]
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Peres RG, Tonin FG, Tavares MF, Rodriguez-Amaya DB. Determination of catechins in green tea infusions by reduced flow micellar electrokinetic chromatography. Food Chem 2011; 127:651-5. [DOI: 10.1016/j.foodchem.2010.12.104] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2009] [Revised: 10/22/2010] [Accepted: 12/29/2010] [Indexed: 11/29/2022]
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12
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Lynen F, Saveedra L, Nickerson B, Sandra P. Evaluation of a multiarray system for pharmaceutical analysis by microemulsion electrokinetic chromatography. Talanta 2011; 84:724-9. [DOI: 10.1016/j.talanta.2011.01.070] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2010] [Revised: 01/13/2011] [Accepted: 01/30/2011] [Indexed: 10/18/2022]
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Application and potential of capillary electroseparation methods to determine antioxidant phenolic compounds from plant food material. J Pharm Biomed Anal 2010; 53:1130-60. [PMID: 20719447 DOI: 10.1016/j.jpba.2010.07.028] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2010] [Revised: 07/09/2010] [Accepted: 07/18/2010] [Indexed: 12/17/2022]
Abstract
Antioxidants are one of the most common active ingredients of nutritionally functional foods which can play an important role in the prevention of oxidation and cellular damage inhibiting or delaying the oxidative processes. In recent years there has been an increased interest in the application of antioxidants to medical treatment as information is constantly gathered linking the development of human diseases to oxidative stress. Within antioxidants, phenolic molecules are an important category of compounds, commonly present in a wide variety of plant food materials. Their correct determination is pivotal nowadays and involves their extraction from the sample, analytical separation, identification, quantification and interpretation of the data. The aim of this review is to provide an overview about all the necessary steps of any analytical procedure to achieve the determination of phenolic compounds from plant matrices, paying particular attention to the application and potential of capillary electroseparation methods. Since it is quite complicated to establish a classification of plant food material, and to structure the current review, we will group the different matrices as follows: fruits, vegetables, herbs, spices and medicinal plants, beverages, vegetable oils, cereals, legumes and nuts and other matrices (including cocoa beans and bee products). At the end of the overview, we include two sections to explain the usefulness of the data about phenols provided by capillary electrophoresis and the newest trends.
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Abstract
Phenolics are structurally assorted and are generally part of a complex mixture isolated from plant and biological origin matrices. A wide gamut of natural products have been the focus of main study for phenolic compounds while urine and blood are the two main biological fluids that have been analyzed for metabolism studies. Traditional and more advanced techniques have come to prominence for sample preparation, detection, and identification. This review is devoted to a short discussion of the occurrence of phenolic acids and flavonoids, their role in human health, and focuses on a detailed presentation of the analytical methods, concluding with the advantages of analytical methods employed so far and prospects. Strategies and practical aspects for the determination of phenolic acids and flavonoids in biological fluids, beverages, plants, and food are reported. Novel and past applications are provided with significant treatment and detection-related developments on the basis of the employment of separation and non-separation analytical techniques.
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Affiliation(s)
- Constantine D Stalikas
- Laboratory of Analytical Chemistry, Department of Chemistry, University of Ioannina, Ioannina, Greece
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15
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Optimization of a method for determination of phenolic acids in exotic fruits by capillary electrophoresis. J Pharm Biomed Anal 2010; 51:430-8. [DOI: 10.1016/j.jpba.2009.05.014] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2009] [Revised: 05/12/2009] [Accepted: 05/18/2009] [Indexed: 11/21/2022]
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16
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Valls J, Millán S, Martí MP, Borràs E, Arola L. Advanced separation methods of food anthocyanins, isoflavones and flavanols. J Chromatogr A 2009; 1216:7143-72. [PMID: 19691963 DOI: 10.1016/j.chroma.2009.07.030] [Citation(s) in RCA: 182] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2009] [Revised: 06/15/2009] [Accepted: 07/02/2009] [Indexed: 01/13/2023]
Abstract
In recent years, increasing knowledge of the positive health effects of food polyphenols has prompted the need to develop new separation techniques for their extraction, fractionation and analysis. This article provides an updated and exhaustive review of the application of counter-current chromatography, high performance liquid chromatography, capillary electrophoresis, and their hyphenation with mass spectrometry to the study of food polyphenols. Flavonoids constitute the largest class of polyphenols, widely spread in the plant kingdom and common in human diet which has been the most widely studied with respect to their antioxidant and biological activities. The main subgroups are anthocyanins, catechins, isoflavones, flavonols and flavones. They are reported to exhibit antioxidant, anti-carcinogenic, anti-inflammatory, anti-atherogenic, anti-thrombotic, and immune modulating functions, among others. Since red fruit anthocyanins, soy isoflavones and flavanols from grapes and teas are currently the most used phenolic compounds for producing new nutraceuticals and functional foods, this review is focused on these three flavonoid groups.
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Stalikas CD. Extraction, separation, and detection methods for phenolic acids and flavonoids. J Sep Sci 2008; 30:3268-95. [PMID: 18069740 DOI: 10.1002/jssc.200700261] [Citation(s) in RCA: 446] [Impact Index Per Article: 27.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The impetus for developing analytical methods for phenolic compounds in natural products has proved to be multifaceted. Hundreds of publications on the analysis of this category of compounds have appeared over the past two decades. Traditional and more advanced techniques have come to prominence for sample preparation, separation, detection, and identification. This review provides an updated and extensive overview of methods and their applications in natural product matrices and samples of biological origin. In addition, it critically appraises recent developments and trends, and provides selected representative bibliographic examples.
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Cheung RHF, Marriott PJ, Small DM. CE methods applied to the analysis of micronutrients in foods. Electrophoresis 2008; 28:3390-413. [PMID: 17847130 DOI: 10.1002/elps.200700100] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
This article reviews the applications of CE that are relevant to the analysis of small molecules in foods. CE has been applied to a wide range of important areas of food analysis and is rapidly being established as an alternative technique to chromatographic methods including HPLC and GC within analytical food and research laboratories. In recent years the analysis of food by CE has become more frequent and important and as such a variety of compounds have been separated and quantified. Although many other analytes have been detected by CE, this review will highlight areas relating primarily to the rather broad chemical classes of free amino acids, carbohydrates, organic acids, vitamins and a variety of antioxidants. In addition, information relating to the analyte, sample matrix, mode of CE employed, scope of the methodology and the detection and derivatization of the small molecules are considered and discussed.
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Affiliation(s)
- Rodney Hau Fung Cheung
- Applied Chemistry, School of Applied Sciences, RMIT University, Melbourne 3001, Victoria, Australia
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Nogueira T, do Lago CL. Determination of caffeine in coffee products by dynamic complexation with 3,4-dimethoxycinnamate and separation by CZE. Electrophoresis 2007; 28:3570-4. [PMID: 17768736 DOI: 10.1002/elps.200700039] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
A method based on the formation of pi-complexes with chlorogenate-like species was proposed for the determination of caffeine in regular (nondecaffeinated) and decaffeinated coffee. Both caffeate and 3,4-dimethoxycinnamate were able to transform caffeine--a neutral species in aqueous solutions--into an anionic species. The usage of 3,4-dimethoxycinnamate in the running electrolyte is advantageous, because of its greater chemical stability and the improved resolution of the peaks of caffeine, theobromine, and theophylline. Negative peaks were registered with a capacitively coupled contactless conductivity detector when solutions of these alkylxanthines were analyzed with a BGE composed of 20 mmol/L 3,4-dimethoxycinnamic acid and pH adjusted to 8.5 with Tris. This behavior was expected, because the complex is larger and thus should move slower than the free anion. Caffeine was determined in ground and instant coffee with precision and accuracy that meet Brazilian norms about such products. The LOD was estimated as 33 mg/L, which corresponds to 0.8 and 0.3 mg of caffeine per gram of dry instant coffee and ground coffee, respectively. For the case of decaffeinated coffee, ten times preconcentration with dichloromethane was carried out to allow the quantitation of caffeine, which should not exceed the concentration of 1 mg/g in dry matter.
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Affiliation(s)
- Thiago Nogueira
- Departamento de Química Fundamental, Instituto de Química, Universidade de São Paulo, Avenida Prof. Lineu Prestes 748, CEP 05508-000 São Paulo, SP, Brazil
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Huang HY, Huang IY, Liang HH, Lee S. Sample stacking for the analysis of catechins by microemulsion EKC. Electrophoresis 2007; 28:1735-43. [PMID: 17464960 DOI: 10.1002/elps.200600413] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
In this study, an on-line concentration method, ASEI (anion-selective exhaustive injection)-sweeping technology which was coupled with microemulsion EKC (MEEKC), was used to analyze and detect six catechins ((-)-epicatechin, (+)-catechin, (-)-epigallocatechin gallate, (-)-epicatechin gallate, (-)-epigallocatechin, and (-)-gallocatechin). In addition to the effects of the buffer pH and electrolyte concentration on stacking, the compositions of microemulsion (types of oil phase, and types and levels of cosurfactant) also dominated the stacking effect of catechins. In MEEKC, the effect of the type of oil in microemulsion on separation mechanism is often unclear. This study had demonstrated that the oil type in microemulsion indeed altered the affinity of oil droplets with analytes. Finally, this proposed ASEI-sweeping MEEKC method was able to detect trace level of catechins in food products that was not previously possible by a normal MEEKC method.
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Affiliation(s)
- Hsi-Ya Huang
- R&D Center for Membrane Technology, Department of Chemistry, Center for Nanotechnology at CYCU, Chung Yuan Christian University, Chung-Li, Taiwan, R.O.C.
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McEvoy E, Marsh A, Altria K, Donegan S, Power J. Recent advances in the development and application of microemulsion EKC. Electrophoresis 2007; 28:193-207. [PMID: 17136741 DOI: 10.1002/elps.200600451] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Microemulsion EKC (MEEKC) is an electrodriven separation technique. Separations are typically achieved using oil-in-water microemulsions, which are composed of nanometre-sized oil droplets suspended in an aqueous buffer. The droplets are stabilised by a surfactant and a cosurfactant. The novel use of water-in-oil microemulsions has also been investigated. This review summarises the advances in the development of MEEKC separations and also the different areas of application including determination of log P values, pharmaceutical applications, chiral analysis, natural products and bioanalytical separations and the use of new methods such as multiplexed MEEKC and high speed MEEKC. Recent applications (2004-2006) are tabulated for each area with microemulsion composition details.
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Affiliation(s)
- Eamon McEvoy
- Department of Chemical and Life Sciences, Waterford Institute of Technology, Cork Road, Waterford, Ireland.
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Huang HY, Lien WC, Huang IY. Anion-selective exhaustive injection-sweeping microemulsion electrokinetic chromatography. Electrophoresis 2006; 27:3202-9. [PMID: 16850505 DOI: 10.1002/elps.200500876] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In this study, anion-selective exhaustive injection-sweeping (ASEI-sweeping) technique, which is a selective on-line sample concentration technique, was first proposed in microemulsion electrokinetic chromatography (MEEKC) for analyses of eight acidic phenolic compounds. In contrast to a capillary that is typically filled with nonmicellar background solution in conventional ASEI-sweeping MEKC method, in the proposed ASEI-sweeping MEEKC method, a capillary is filled with a low pH microemulsion solution (pH 2.0), and then with a short acid plug (pH 2.0, 1.9 cm) before field-amplified sample injection. This proposed design has two functions. First, the microemulsion solution that is present at the front of capillary column is able to avoid phase separation of microemulsion solution during MEEKC separation. Second, the presence of the short acid plug would effectively limit the partition behavior of acid analytes with the oil droplets in the microemulsion during field-amplified sample injection; otherwise, the stacking effect of acid analytes would be markedly reduced. This optimal ASEI-sweeping MEEKC method afforded about 96,000-fold to 238,000-fold increases in detection sensitivity in terms of peak areas without any separation efficiency loss when compared to normal MEEKC separation. Furthermore, trace levels (about 3 ng/g) of gallic acid and catechin in foods were also detected successfully by the proposed ASEI-sweeping MEEKC technique.
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Affiliation(s)
- Hsi-Ya Huang
- Department of Chemistry, Center for Nanotechnology at CYCU, Chung Yuan Christian University, Chung-Li, Taiwan, China.
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Abstract
Compared to MEKC, the presence of a water-immiscible oil phase in the microemulsion droplets of microemulsion EKC (MEEKC) gives rise to some special properties, such as enhanced solubilization capacity and enlarged migration window, which could allow for the improved separation of various hydrophobic and hydrophilic compounds, with reduced sample pretreatment steps, unique selectivities and/or higher efficiencies. Typically, stable and optically clear oil-in-water microemulsions containing a surfactant (SDS), oil (octane or heptane), and cosurfactant (1-butanol) in phosphate buffer are employed as separation media in conventional MEEKC. However, in recent years, the applicability of reverse MEEKC (water-in-oil microemulsions) has also been demonstrated, such as for the enhanced separation of highly hydrophobic substances. Also, during the past few years, the development and application of MEEKC for the separation of chiral molecules has been expanded, based on the use of enantioselective microemulsions that contained a chiral surfactant or chiral alcohol. On the other hand, the application of MEEKC for the characterization of the lipophilicity of chemical substances remains an active and important area of research, such as the use of multiplex MEEKC for the high-throughput determination of partition coefficients (log P values) of pharmaceutical compounds. In this review, recent applications of MEEKC (covering the period from 2003 to 2005) are reported. Emphases are placed on the discussion of MEEKC in the separation of chiral molecules and highly hydrophobic substances, as well as in the determination of partition coefficients, followed by a survey of recent applications of MEEKC in the analysis of pharmaceuticals, cosmetics and health-care products, biological and environmental compounds, plant materials, and foods.
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Affiliation(s)
- Carmen W Huie
- Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong, China.
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Cifuentes A. Recent advances in the application of capillary electromigration methods for food analysis. Electrophoresis 2006; 27:283-303. [PMID: 16307427 DOI: 10.1002/elps.200500474] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
This article reviews the latest developments in the application of capillary electromigration methods for the analysis of foods and food components. Nowadays, methods based on CE techniques are becoming widely used in food analytical and research laboratories. This review covers the application of CE to analyze amino acids, biogenic amines, peptides, proteins, DNAs, carbohydrates, phenols, polyphenols, pigments, toxins, pesticides, vitamins, additives, small organic and inorganic ions, chiral compounds, and other compounds in foods, as well as to investigate food interactions and food processing. The use of microchips as well as other foreseen trends in CE analysis of foods is discussed. Papers that were published during the period June 2002-June 2005 are included following the previous review by Frazier and Papadopoulou (Electrophoresis 2003, 24, 4095-4105).
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Affiliation(s)
- Alejandro Cifuentes
- Department of Food Analysis, Institute of Industrial Fermentations (CSIC), Madrid, Spain.
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