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Shen MH, Singh RK. Determining aflatoxins in raw peanuts using immunoaffinity column as sample clean-up method followed by normal-phase HPLC-FLD analysis. Food Control 2022. [DOI: 10.1016/j.foodcont.2022.109065] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Shen MH, Singh RK. Effective UV wavelength range for increasing aflatoxins reduction and decreasing oil deterioration in contaminated peanuts. Food Res Int 2022; 154:111016. [DOI: 10.1016/j.foodres.2022.111016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Revised: 02/11/2022] [Accepted: 02/12/2022] [Indexed: 12/25/2022]
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Ultrasensitive aflatoxin B1 assay based on FRET from aptamer labelled fluorescent polymer dots to silver nanoparticles labeled with complementary DNA. Mikrochim Acta 2017. [DOI: 10.1007/s00604-017-2508-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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Netto-Ferreira JC, Heyne B, Scaiano JC. Photophysics and photochemistry of aflatoxins B1 and B2. Photochem Photobiol Sci 2011; 10:1701-8. [DOI: 10.1039/c1pp05103b] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Abbas HK, Shier WT, Horn BW, Weaver MA. Cultural Methods for Aflatoxin Detection. ACTA ACUST UNITED AC 2008. [DOI: 10.1081/txr-200027854] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Amadasi A, Dall'asta C, Ingletto G, Pela R, Marchelli R, Cozzini P. Explaining cyclodextrin–mycotoxin interactions using a ‘natural’ force field. Bioorg Med Chem 2007; 15:4585-94. [PMID: 17449255 DOI: 10.1016/j.bmc.2007.04.006] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2006] [Revised: 04/03/2007] [Accepted: 04/05/2007] [Indexed: 11/19/2022]
Abstract
Docking techniques and the HINT (Hydropathic Interaction) program were used to explain interactions of aflatoxin B(1) and ochratoxin A with beta- and gamma-cyclodextrins. The work was aimed at designing a chemosensor to identify very low concentrations of these mycotoxins by exploiting the affinity of the cyclodextrin cavity for many small organic molecules. Actually, the inclusion of the fluorescent portion of these toxins into the cavity may lower the quenching effect of the solvent, thus enhancing the luminescence. HINT is a 'natural' force field, based on experimentally determined LogP(octanol/water) values, that is able to consider both enthalpic and entropic contributions to the binding free energy with an unified approach. HINT is normally applied to predict the DeltaG degrees of binding for protein-ligand, protein-protein, and protein-DNA interactions. The leading forces in biomolecular processes are the same as those involved in organic host-guest inclusion phenomena, therefore we applied this methodology for the first time to cyclodextrin complexes. The results allowed us to explain spectroscopic data in absence of available crystallographic or NMR structural data.
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Affiliation(s)
- Alessio Amadasi
- Department of Biochemistry and Molecular Biology, University of Parma, I-43100 Parma, Italy
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Ramírez-Galicia G, Garduño-Juárez R, Gabriela Vargas M. Effect of water molecules on the fluorescence enhancement of Aflatoxin B1 mediated by Aflatoxin B1:β-cyclodextrin complexes. A theoretical study. Photochem Photobiol Sci 2007; 6:110-8. [PMID: 17200746 DOI: 10.1039/b614107b] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
In order to explain the observed fluorescence enhancement of Aflatoxin B1 (AFB1) when forming AFB1:beta-cyclodextrin (AFB1:beta-CD) inclusion complexes, we have performed a theoretical (quantum chemistry calculations) study of AFB1 and AFB1:beta-CD in vacuum and in the presence of aqueous solvent. The AM1 method was used to calculate the absorption and emission wavelengths of these molecules. With the help of density functional theory (DFT) and time-dependent DFT (TDDFT) vibrational frequencies and related excitation energies of AFB1 and AFB1.(H2O)m = 4,5,6,11 were calculated. On the basis of these calculations we propose a plausible mechanism for the fluorescence enhancement of AFB1 in the presence of beta-CD: (1) before photoexcitation of AFB1 to its S1 excited state, there is a vibrational coupling between the vibrational modes involving the AFB1 carbonyl groups and the bending modes of the nearby water molecules (CG + WM); (2) these interactions allow a thermal relaxation of the excited AFB1 molecules that results in fluorescence quenching; (3) when the AFB1 molecules form inclusion complexes with beta-CD the CG + WM interaction decreases; and (4) this gives rise to a fluorescence enhancement.
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Abbas HK, Zablotowicz RM, Weaver MA, Horn BW, Xie W, Shier WT. Comparison of cultural and analytical methods for determination of aflatoxin production by Mississippi DeltaAspergillusisolates. Can J Microbiol 2004; 50:193-9. [PMID: 15105886 DOI: 10.1139/w04-006] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This study compared cultural and analytical methods for detecting aflatoxin production by Aspergillus species. Aspergillus isolates were obtained from various Mississippi Delta crops (corn, peanut, rice, cotton) and soils. Most of the isolates (99%) were A. flavus and the remainder comprised A. parasiticus and A. nomius. The following three cultural methods were evaluated on potato dextrose agar: fluorescence (FL) on β-cyclodextrin-containing media (CD), yellow pigment (YP) formation in mycelium and medium, and color change after ammonium hydroxide vapor exposure (AV). Aflatoxins in culture extracts were confirmed by thin-layer chromatography (TLC) and quantified by enzyme-linked immunosorbent assay (ELISA). Of the 517 isolates, 314 produced greater than 20 ng/g of total aflatoxin based on ELISA, and 180 produced greater than 10 000 ng/g of aflatoxin in the medium. Almost all the toxigenic isolates (97%) were confirmed by TLC as producers. Of the toxigenic isolates, as determined by ELISA, 93%, 73%, and 70% gave positive FL, YP, and AV responses, respectively. Of the 203 isolates producing less than 20 ng/g of aflatoxin, 20%, 6%, and 0% of respective FL, YP, and AV methods gave false-positive responses. The 9% false-positive results from TLC fall within this range. This study showed good agreement among all tested cultural methods. However, these cultural techniques did not detect aflatoxin in all cultures that were found to produce aflatoxins by ELISA, LC/MS, and TLC. The best results were obtained when the AV color change and CD fluorescence methods were used together, yielding an overall success rate comparable to TLC but without the need for chemical extraction and the time and expense of TLC.Key words: aflatoxins, analytical methods, Aspergillus flavus, Aspergillus parasiticus, cultural methods, β-cyclodextrin, fluorescence enhancers, mycotoxins, yellow pigment.
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Affiliation(s)
- Hamed K Abbas
- Crop Genetics and Production Research Unit, Stoneville, MS 38776, USA.
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Chiavaro E, Dall'Asta C, Galaverna G, Biancardi A, Gambarelli E, Dossena A, Marchelli R. New reversed-phase liquid chromatographic method to detect aflatoxins in food and feed with cyclodextrins as fluorescence enhancers added to the eluent. J Chromatogr A 2001; 937:31-40. [PMID: 11765082 DOI: 10.1016/s0021-9673(01)01300-0] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The effect of succynil-beta-cyclodextrin (beta-CD-Su), dimethyl-beta-cyclodextrin (DIMEB) and beta-cyclodextrin (beta-CD) on the fluorescence of aflatoxins B1, B2, G1, G2 and M1 (AFB1, AFB2, AFG1, AFG2 and AFM1) was studied: beta-CD-Su promoted the largest fluorescence enhancement for AFB1 and AFM1 while DIMEB showed better results for AFG1 . On the basis of the fluorescence enhancement, a new RP-HPLC method for detecting aflatoxins B1, B2, G1, G2 and M1 was developed using cyclodextrins directly dissolved in the LC eluent. Aflatoxins B1, B2, G1 and G2 were resolved using a MICRA NPS ODS-1 column using methanol-water as mobile phase to which 6 x 10(-3) M beta-CD-Su or beta-CD were added. Chromatographic responses of AFB1 and AFG1 achieved using beta-CD dissolved in the mobile phase were enhanced, respectively, 8 and 12 times, and 10 and 15 times with beta-CD-Su. Detection limits lower than 0.3 microg/kg were achieved for all the four aflatoxins. Aflatoxin M1 was analysed using a Spherisorb S3 ODS-2 Narrow Bore column and methanol-water as mobile phase with added 2 x 10(-3) M beta-CD-Su. An area enhancement of 1.5 was detected for the toxin and the detection limit achieved under these analytical conditions was lower than 0.0005 microg/kg. Both methods were statistically validated showing a linear response for all the aflatoxins tested (R2 > or = 0.99), and applied to the analysis of spiked and naturally contaminated food samples.
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Affiliation(s)
- E Chiavaro
- Dipartimento di Chimica Organica e Industriale dell'Università, Parma, Italy
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Lin L, Zhang J, Wang P, Wang Y, Chen J. Thin-layer chromatography of mycotoxins and comparison with other chromatographic methods. J Chromatogr A 1998; 815:3-20. [PMID: 9718702 DOI: 10.1016/s0021-9673(98)00204-0] [Citation(s) in RCA: 100] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This paper highlights the status of thin-layer chromatography (TLC) of mycotoxins in various sample matrices. The outstanding merits of TLC in the field of the qualitative and quantitative determination of mycotoxins have been briefed. A comparison between different TLC methods and TLC with HPLC, enzyme-linked immunosorbent assay and GC methods, etc. is made, in general.
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Affiliation(s)
- L Lin
- Dalian Institute of Chemical Physics, Chinese Academy of Sciences, China
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Cepeda A, Franco CM, Fente CA, Vázquez BI, Rodríguez JL, Prognon P, Mahuzier G. Postcolumn excitation of aflatoxins using cyclodextrins in liquid chromatography for food analysis. J Chromatogr A 1996; 721:69-74. [PMID: 8653196 DOI: 10.1016/0021-9673(95)00566-8] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Measurement of fluorescence increase was used for the comparative quantification of the effect that several cyclodextrins (alpha-, beta-, heptakis-2,6-beta-omicron-dimethyl- and gamma-) produce on the fluorescent response of aflatoxins B1 and G1. This constitutes a new chromatographic method with stability of the mobile phase, and shows general improvements in the chromatographic conditions with respect to other methods (especially those using an iodine reservoir as a postcolumn reactor). A C18-type column was used, with methanol-water (60:40, v/v) as the mobile phase. The excitation phase of the natural fluorescence of aflatoxins, a 10(-2) M solution of each cyclodextrin, was introduced postcolumn. The determination of the elution order aflatoxin G2 > G1 > B2 > B1 was performed for each phase in less than 15 min. As expected using an aqueous-alcoholic medium, an increase in the fluorescence response of aflatoxins with an unsaturated furanic ring was found to occur with all the cyclodextrins studied, except gamma-cyclodextrin. The observed increase was larger for heptakis-2,6-beta-omicron-dimethyl- than for beta-cyclodextrin (to our knowledge, the only cyclodextrin previously described in the literature to serve for the determination of aflatoxins). The difference is of the order of 70.1-fold in the case of aflatoxin G1 and 45.2-fold in the case of aflatoxin B1. The detection limit in the mobile phase used was determined (for aflatoxin B1) for beta-cyclodextrin and 2,6-beta-omicron-dimethylcyclodextrin (signal-to-noise ratio 1:3) to be 4 and 9 mg 1(-1), respectively.
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Affiliation(s)
- A Cepeda
- Laboratorio de Higiene e Inspección de Alimentos, Universidad de Santiago de Compostela, Lugo, Spain
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Kok WT. Derivatization reactions for the determination of aflatoxins by liquid chromatography with fluorescence detection. JOURNAL OF CHROMATOGRAPHY. B, BIOMEDICAL APPLICATIONS 1994; 659:127-37. [PMID: 7820273 DOI: 10.1016/0378-4347(94)00152-9] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Various derivatization methods for the fluorometric detection of aflatoxins after separation by HPLC are reviewed. In normal-phase chromatography the sensitivity for aflatoxins B1 and B2 was improved by using special mobile phases or a flow cell packed with silica-gel particles. In the nowadays more popular reversed-phase methods, the fluorescence intensity of B1 and G1 can be increased by precolumn derivatization with trifluoroacetic acid or by postcolumn derivatization with iodine or bromine. Optimum conditions for the reactions are discussed. In terms of sensitivity, the three derivatization schemes give similar results. The methods are compared with respect to experimental convenience, selectivity, reproducibility and suitability for automation.
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Affiliation(s)
- W T Kok
- Laboratory for Analytical Chemistry, University of Amsterdam, Netherlands
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Chapter 7 Thin-Layer Chromatography of Mycotoxins. CHROMATOGRAPHY OF MYCOTOXINS - TECHNIQUES AND APPLICATIONS 1993. [DOI: 10.1016/s0301-4770(08)60567-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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Holcomb M, Wilson DM, Trucksess MW, Thompson HC. Determination of aflatoxins in food products by chromatography. J Chromatogr A 1992; 624:341-52. [PMID: 1494012 DOI: 10.1016/0021-9673(92)85687-o] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Several chromatographic methods for the determination of aflatoxins in agricultural and food products are reviewed. During the past two decades, identification and determination of aflatoxins were done by thin-layer chromatography (TLC) because it was easy, fast and inexpensive. However, high-performance liquid chromatography (HPLC) using fluorescence detection is now the method of choice for determining aflatoxins and is also growing in popularity for their identification. The reasons for selecting HPLC over TLC can be summarized as the ability to analyze for a wide variety of compounds, including compounds that are easily degraded by heat, light or air, the ease of adaptation to confirmatory procedures, the potential for automation and the dramatic improvement in instrumentation, including the development of increasingly sensitive fluorescence and electrochemical detectors and short, high-resolution, reversed-phase columns.
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Affiliation(s)
- M Holcomb
- National Center for Toxicological Research, Food and Drug Administration, Jefferson, AR 72079
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Vazquez M, Cepeda A, Prognon P, Mahuzier G, Blais J. Cyclodextrins as modifiers of the luminescence characteristics of aflatoxins. Anal Chim Acta 1991. [DOI: 10.1016/0003-2670(91)80066-3] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Abstract
Achievements in the applications of chromatographic techniques in mycotoxicology are reviewed. Historically, column chromatography (CC) and paper chromatography (PC) were applied first, followed by thin-layer chromatography (TLC), high-performance liquid chromatography (HPLC) and gas chromatography (GC). Although PC techniques are no longer used in the analysis of mycotoxins, selected applications of PC are included to underline historical continuity. The most important achievements published from 1980 onwards are described. They include clean-up methods, TLC, CC, HPLC and GC of mycotoxins in environmental samples, foods, feeds, body fluids and in studies on biosynthesis and biotransformations of mycotoxins. Advantages and disadvantages of chromatographic techniques used in mycotoxicology are also evaluated.
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Affiliation(s)
- V Betina
- Department of Environmental Chemistry and Technology, Faculty of Chemistry, Slovak Polytechnical University, Bratislava, Czechoslovakia
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