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ABSTRACT: Differentiation of silver, gold, aged and extra-aged tequila using 1-propanol, ethyl acetate, 2-methyl-1-propanol, 3-methyl-1-butanol and 2-methyl-1-butanol and furan derivatives like 5-(hydroxymethyl)-2-furaldehyde and 2-furaldehyde has been carried out. The content of 1-propanol, ethyl acetate, 2-methyl-1-propanol, 3-methyl-1-butanol and 2-methyl-1-butanol was determined by means of head space solid phase microextraction gas chromatography mass-spectrometry. 5-(Hydroxymethyl)-2-furaldehyde and 2-furaldehyde were determined by high performance liquid chromatography with diode array detection. Kruskal-Wallis test was used to highlight significant differences between types of tequila. Principal component analysis was applied as visualisation technique. Linear discriminant analysis and multilayer perceptron artificial neural networks were used to construct classification models. The best classification performance was obtained when multilayer perceptron model was applied.
Food Chemistry 02/2013; 136(3-4):1309-15. · 3.65 Impact Factor
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ABSTRACT: An isocratic LC method for the determination of melamine and its degradation products (ammelide, ammeline, and cyanuric acid), used to increase the apparent protein content of rice protein concentrate, has been developed. Method development involved optimization of different RP columns, aqueous mobile phases, pH, phosphate concentration, and temperature. The optimum separation of these compounds was achieved using a Luna CN column (30 degrees C), 5 mmol L(-1) sodium phosphate (pH 5.0) as mobile phase, 1 mL min(-1) flow-rate, UV absorbance-DAD detection at 220 nm, and resorcine as internal standard; this enabled separation of these compounds with baseline resolution (values in the 2.1-10.1 range) in about 8 min. Prior to HPLC, the developed sample preparation procedure consisted in a leaching process using the above mentioned mobile phase. Method validation was carried out in rice protein concentrates in accordance with the European Commission decision 2002/657/EC criteria. For this purpose, eight mandatory performance characteristics for the conventional validation approach were determined: calibration graphs, extraction efficiencies, decision limits, detection capabilities, precision (repeatability and within-laboratory reproducibility), accuracy, selectivity, and robustness. The extraction efficiencies for these compounds were in the range 99-100% and the within-laboratory reproducibility at 1.0, 1.5, and 2.0 detection capabilities concentration levels were smaller than 5, 4, and 3%, respectively. Finally, the proposed method was successfully applied to the analysis of other rice protein concentrates and several animal feed samples.
Analytical and Bioanalytical Chemistry 11/2008; 392(3):523-31. · 3.78 Impact Factor
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ABSTRACT: An improved sample preparation procedure for the determination of 17 steroids (corticoids (CC) and androgenic anabolic steroids (AAS)), used potentially as growth promoters, in feed samples has been developed. This procedure is based on two reported LC-UV methods. The improved procedure includes a leaching process using ACN, saponification, and SPE using polymeric cartridges. The proposed method was validated according to the EU criteria established for quantitative screening methods in PFS. The extraction efficiencies, decision limits (CCalpha) and detection capabilities (CCbeta), for these compounds were in the ranges of 82-100%, 19-40, and 24-53 microg/kg, respectively. The repeatability and the within-laboratory reproducibility at 1.0, 1.5, and 2.0 CCbeta levels were smaller than 10%. Accuracy was in the 97-101% range. The robustness was evaluated using the Youden robustness test. This method was applied to the analysis of steroids in different kinds of FS with satisfactory results.
Journal of Separation Science 08/2008; 31(12):2303-9. · 2.73 Impact Factor
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ABSTRACT: A GC-MS method for the determination of AAS used as growth promoting agents using SIM in piglet feed samples has been developed and validated, using testosterone as internal standard. The formation of volatile steroid derivatives was carried out by derivatization with N-methyl-N-(trimethylsilyl)trifluoroacetamide. The optimum separation was achieved using a Zebron ZB-5 column under a gradient temperature elution, allowing the separation of steroids in 18 min. The required sample treatment process was discussed. A leaching using ACN, saponification using a binary NaOH/MgCl2 solution, and LLE using ethyl acetate were finally selected. Method validation has been carried out according to the Commission Decision 2002/657/EC criteria established for quantitative confirmatory methods. The extraction efficiencies, CCalpha and CCbeta for these compounds were in the ranges 78-98%, 10-21 and 18-35 mug/kg, respectively. The repeatability and the within-laboratory reproducibility at 1, 1.5, and 2 CCbeta concentration levels were smaller than 8.2, 7.5, and 5.8% and 12.2, 9.5, and 7.5%, respectively. Accuracy was in the 99-103% range. The robustness was evaluated using the Youden robustness test. The proposed method was applied to the analysis of steroids spiked in different kinds of animal feed samples with satisfactory results.
Journal of Separation Science 04/2008; 31(4):727-34. · 2.73 Impact Factor
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ABSTRACT: Several isocratic separations for the determination of 20 steroids (STER) in animal feeding water samples (AFWS) from drinking-trough by LC using a mobile phase ACN/H(2)O (35:65 v/v) and different RP columns (Hypersil C18, Gemini C18 (GM), Purospher Star C18, Synergi Max C12, and Synergi Fusion) and UV detection were obtained. The elution order was the same: a first group of corticoids (CC) was early eluted, a second group of CC and anabolics (AAS) exhibited intermediate retention, and a third group constituted by AAS was strongly retained. To improve the separation performances of the isocratic separations an ACN gradient elution optimization was carried out for each column. The most satisfactory results were obtained using a Purospher column which allowed the separation of 19 STER in an analysis time close to 26 min. After sample preparation using SPE, method validation was performed in an AFWS spiked with STER according to the EC decision criteria established for quantitative screening methods. For this purpose calibration graphs, extraction efficiencies, decision limits, detection capabilities, precision (repeatability and within-laboratory reproducibility), accuracy, selectivity, and robustness were evaluated. The proposed method was applied to other AFWS with satisfactory results.
Journal of Separation Science 03/2008; 31(2):219-28. · 2.73 Impact Factor
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ABSTRACT: A LC method for corticosteroids (CC) determination in poultry feed using a Chromolith column and UV detection has been developed and validated. The method development involved the optimization of different hydro-organic mobile phases using methanol or ACN as organic modifiers, flow rate, and temperature. The optimum separation was achieved at 40 degrees C using ACN/water (21:79 v/v) as mobile phase and 3 mL/min flow rate, allowing the separation to baseline of four out of seven CC in about 10 min. Prior to LC, a sample preparation procedure previously assayed for anabolics was used. It includes a leaching process, saponification of the esters from fatty acids, and SPE. Method validation was carried out according to the EU criteria established for quantitative screening methods. The extraction efficiencies, decision limits (CCalpha), and detection capabilities (CCbeta) for these compounds were in the ranges of 86-92%, 27-36 microg/kg, and 33-43 microg/kg, respectively. The repeatability and the within-laboratory reproducibility at 1, 1.5, and 2 CCbeta concentration levels were smaller than 9.0, 5.0, and 4.2% and 9.4, 6.4, and 4.9%, respectively. The CV values of the robustness test were less than 3.8% and the accuracy was in the range of 98-103%. The proposed method was applied to other feed with satisfactory results.
Journal of Separation Science 12/2007; 30(17):2950-7. · 2.73 Impact Factor
