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  • 1
    Electronic Resource
    Electronic Resource
    Isospin-forbidden analog resonances in direct reactions
    Amsterdam : Elsevier
    Physics Letters B 30 (1969), S. 581-584 
    Details
    ISSN: 0370-2693
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0370-2693(69)90062-8
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  • 2
    Electronic Resource
    Electronic Resource
    A normal phase HPTLC method for the quantitative determination of ochratoxin A in rice (1996)
    Springer
    Chromatographia 42 (1996), S. 25-28 
    Details
    ISSN: 1612-1112
    Keywords: High-performance thin-layer chromatography (HPTLC) ; Solid phase extraction ; Parboiled rice ; Ochratoxin A
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A previously published [1] liquid chromatographic method for the determination of ochratoxin A in corn, barley and kidney has been modified for application to parboiled rice with quantification by high performance thin layer chromatography (HPTLC). The method has been validated by spiking uncontaminated extracts of rice with ochratoxin A over the range 0 to 198 μg kg−1. The proposed method has some significant advantages over the current AOAC method [2], especially for determining low levels of ochratoxin A in parboiled rice.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02271050
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  • 3
    Electronic Resource
    Electronic Resource
    An HPTLC method for the quantitative determination of zearalenone in maize (1998)
    Springer
    Chromatographia 47 (1998), S. 215-218 
    Details
    ISSN: 1612-1112
    Keywords: Thin-layer chromatography ; Zearalenone ; Maize
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The high performance liquid chromatographic method adopted by the AOAC [1] for the quantitative analysis of zearalenone has been modified for application to maize, with quantification by high performance thin layer chromatography (HPTLC). The method has been validated by spiking uncontaminated extracts of maize with zearalenone over the range 10 to 320 μg kg−1. A linear relationship was found between 10 and 80 μg kg−1, but at higher levels, the observed values were below the fitted line.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466584
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  • 4
    Electronic Resource
    Electronic Resource
    A normal phase HPTLC method for the quantitative determination of fumonisin B1 in rice (1995)
    Springer
    Chromatographia 41 (1995), S. 187-190 
    Details
    ISSN: 1612-1112
    Keywords: High-performance thin-layer chromatography (HPTLC) ; Solid phase extraction ; Rice ; Maize ; Fumonisin B1
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A normal phase HPTLC method has been validated by spiking, in quadruplet, uncontaminated extract of rice with fumonisin B1 over the range 0 to 16μg/g. The method utilises solid phase extraction using strong anionic exchange (SAX) cartridges, uni-directional normal phase high performance thin layer chromatography (HPTLC), novel visualisation by dipping into a 0.16% acidic solution ofp-anisaldehyde and quantification by scanning fluoro-densitometry. Response was linear only over the range 0 to 5 μg/g (0 to 125 ng/spot) where recoveries averaged 81% for rice. Weighted linear regression yielded a limit of detection of 0.25 μg/g for rice. Coefficients of variance were 15.4, 5.3, 2.8, 3.5, and 0.9% at fumonisin B1 levels of 0.20, 0.5, 1.0, 2.0 and 5 μg/g respectively, demonstrating good precision. This method claims to be the first fully quantitative HPTLC method for determining fumonisin B1 in rice.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02267953
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  • 5
    Electronic Resource
    Electronic Resource
    An HPTLC method for the quantitative determination of T-2 toxin and deoxynivalenol in rice (1999)
    Springer
    Chromatographia 49 (1999), S. 547-551 
    Details
    ISSN: 1612-1112
    Keywords: Thin-layer chromatography (HPTLC) ; Florisil solid phase column clean-up ; Rice ; T-2 toxin ; Deoxynivalenol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A gas chromatographic procedure for the quantitative estimation of T-2 toxin, which utilises a florisil SPE clean-up procedure, has been adapted for the quantitative analysis of both T-2 toxin and deoxynivalenol (DON), but using an high performance thin layer chromatographic quantification step. The method has been validated by spiking uncontaminated rice extracts with T-2 toxin and DON over the range 100 to 1000 μg kg−1. A linear relationship was found for both mycotoxins over the entire range tested. The mean recovery for T-2 toxin was 84% and for DON 91% with mean coefficients of variation of 8.2% and 6.0%, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467757
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  • 6
    Electronic Resource
    Electronic Resource
    Evaluation of non-polar bonded-phases for the clean-up of maize extracts prior to aflatoxin assay by HPTLC (1989)
    Springer
    Chromatographia 27 (1989), S. 67-70 
    Details
    ISSN: 1612-1112
    Keywords: Aflatoxin ; Non-polar bonded phase extraction cartridges ; High performance thin layer chromatography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The ability of a PH non-polar bonded phase to extract aflatoxin from aqueous solutions (1% v/v) containing 5, 10, 20 and 30% acetone, acetonitrile or methanol was determined. The amount of aflatoxin extracted by the cartridge from aqueous solutions remained almost constant (97–102%) as the concentration of methanol increased, but decreased rapidly when the amount of acetone or acetonitrile increased beyond 10%. Examination of the ability of a number of bonded phases (C2, C8, C18, CH and PH) to extract aflatoxin from aqueous methanol extracts of maize revealed that the PH bonded phase was the most efficient. Aflatoxin is eluted from the cartridge by chloroform (7 ml). An additional clean-up step involving bi-directional development was required when quantifying low levels of aflatoxin in maize by HPTLC.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02290408
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  • 7
    Electronic Resource
    Electronic Resource
    A comparative study of phenyl bonded-phase, CB and romer clean-up procedures for determining aflatoxin levels in maize by bi-directional HPTLC (1990)
    Springer
    Chromatographia 29 (1990), S. 177-181 
    Details
    ISSN: 1612-1112
    Keywords: Thin layer chromatography ; Bi-directional development ; Aflatoxin in maize ; Solid phase extraction ; AOAC methods
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A modified phenyl non-polar bonded-phase clean-up procedure for determining aflatoxin concentrations in aqueous acetone extracts of maize by bi-directional HPTLC was assessed. The accuracy and precision of the method was evaluated for a range of aflatoxin concentrations between 3.4 and 901 μg/kg. The coefficients of variation varied between 1.7 and 10.8% with mean recoveries of 92–99%. Application of regression analysis revealed systematic errors for aflatoxins B2 (−0.36 to −1.19%) and G2 (−0.03 to −0.57), and small relative errors for all four toxins. The limits of detection were 1.7 μg/kg (B1), 1.2 μg/kg (B2), 0.9 μg/kg (G1) and 0.8 μg/kg (G2). The method was compared with the first action AOAC CB and Romer methods and a previously described PH bonded-phase procedure. It was found to recover significantly more aflatoxin from a sample of naturally contaminated maize, and to have accuracy better than and precision equivalent to the other methods. In addition, it was shown to be more rapid and cost effective than the AOAC methods.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02268707
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  • 8
    Electronic Resource
    Electronic Resource
    The development and validation of a solid phase extraction/HPLC method for the determination of aflatoxins in groundnut meal (1992)
    Springer
    Chromatographia 33 (1992), S. 208-212 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Solid phase extraction ; Validation ; Aflatoxins in groundnut meal ; CB method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The efficiency of an analytical method for the determination of aflatoxins in groundnut meal has been statistically examined. The procedure consists of a phenyl bonded phase (PH) clean-up of an acetone: water (85∶15) extract followed by HPLC quantification. Average recoveries from spiked groundnut meal extracts were calculated to be 101.3% and 101.8%, with limits of detection of 7.4 and 2.62 μg/kg for aflatoxins-B1 and-B2 respectively. Higher recoveries of aflatoxin-B1 from naturally contaminated samples were recorded using the proposed procedure than those recorded using the official AOAC (CB) method although the precisions of the two methods were not found to differ at the 5% significance level. Similar recoveries of aflatoxin-B2 were recorded for both methods but the proposed procedure was found to be more precise. The proposed PH-HPLC method was far less time consuming and more economical on solvents than the CB procedure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02276184
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  • 9
    Electronic Resource
    Electronic Resource
    A bi-directional HPTLC development method for the detection of low levels of aflatoxin in maize extracts (1989)
    Springer
    Chromatographia 27 (1989), S. 49-52 
    Details
    ISSN: 1612-1112
    Keywords: Thin layer chromatography ; Bi-directional development ; Pre-chromatographic clean-up ; Aflatoxin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A bi-directional high performance thin layer chromatography (HPTLC) method for the determination of low levels of aflatoxin in extracts of maize has been evaluated. The method, using diethylether and chloroform:xylene:acetone (6∶3∶1) as the two developing solvents was found to have a limit of detection of 0.8 (B1), 0.4 (B2), 1.7 (G1) and 0.4 (G2) μg/kg respectivety, with CVs equal or less than 1.7% (B1), 2.5% (B2), 3.1% (G1), and 3.1% (G2). Inter-plate variation was significantly greater than intra-plate variation. Compared with two-dimensional HPTLC methods, a 15 to 30 fold improvement in the sample capacity per plate is achieved and positioning errors are much reduced during densitometry.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02290404
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  • 10
    Electronic Resource
    Electronic Resource
    Evaluation of instrumentation used for high performance thin-layer chromatography of aflatoxins (1988)
    Springer
    Chromatographia 25 (1988), S. 875-880 
    Details
    ISSN: 1612-1112
    Keywords: Thin layer chromatography ; Sample application ; Densitometry ; Development chambers ; Aflatoxins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Instrumentation used for high performance thin layer chromatography (HPTLC) of aflatoxins has been evaluated. Optimum sensitivity, accuracy and precision resulted when a combination of a fully automated TLC sampler, an unsaturated conventional TLC glass chamber and a monochromatic densitometer were employed. Benzene: acetonitrile (98: 2 v/v) was found to be the most suitable sample application solvent. These findings are being used to develop a rapid, simple and reproducible method for the analysis of aflatoxins.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02311421
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