کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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1166520 | 1491125 | 2011 | 9 صفحه PDF | دانلود رایگان |
The present work proposes an analytical procedure to determine sulfathiazole in milk by using molecular fluorescence spectroscopy. For this sulfonamide the European Union in Regulation 37/2010 has established a maximum residue limit in milk of 100 μg kg−1.The study includes the effect of six factors on the recovery of sulfathiazole. The factors are: (i) The one related to the matrix depending on the heat treatment of the milk (UHT, pasteurized); (ii) Those related to the protein precipitation step, namely the ratio between the volume of trichloroacetic acid (TCA) and milk, centrifugation speed and temperature; (iii) Those affecting the derivatization reaction: derivatization time and volume of fluorescamine.To do this, two chemometric tools are used together: a D-optimal design for studying the effect of the factors on the recovery of sulfathiazole, considerably reducing the number of needed experiments; and the second-order property of the PARAFAC (Parallel Factor Analysis) decomposition that avoids the need of fitting a new calibration model each time that the experimental conditions change.It has been found that the type of milk, the TCA:milk ratio and the volume of fluorescamine have significant effect on the response. The rest of factors and interactions are not significant. The best recovery is obtained with UHT milk, 4:6 rate for TCA:milk volumes and 40 μL of fluorescamine. In UHT milk, the mean recovery (n = 5) in the optimal conditions is 88.7% (RSD = 12.4%).As some non-linear behaviour may occur when using fluorescence spectroscopy, the calibration model that relates the fluorescence spectra with the concentration is computed by a partial least squares regression and a multi-layer feed-forward neural network. In both cases, the proposed procedures have been validated according to Decision 2002/657/EC, concluding that the two are accurate although the calibration model built with the neural network has better figures of merit, the decision limit (CCα) for x0 = 100 μg L−1 is 103.3 μg L−1 and the detection capability (CCβ) is 106.5 μg L−1, with the probabilities of false noncompliance (α) and false compliance (β) equal to 5%.
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► Fluorescence spectroscopy is used to determine sulfathiazole in milk.
► Optimization of the procedure is made by coupling a D-optimal design and PARAFAC.
► A neural network showed to be useful to calibrate with fluorescence emission spectra.
► Performance characteristics of the method are evaluated according to 2002/657/EC Decision.
► Detection capability is 106.5 μg L−1 (MRL = 100) for 5% false noncompliance and compliance.
Journal: Analytica Chimica Acta - Volume 707, Issues 1–2, 30 November 2011, Pages 38–46