Determining the adulteration of spices with Sudan I-II-II-IV dyes by UV-visible spectroscopy and multivariate classification techniques

Department of Analytical and Organic Chemistry, Rovira i Virgili University, Marcel.lí Domingo s/n Campus Sescelades, E-43007 Tarragona, Spain.
Talanta (Impact Factor: 3.55). 09/2009; 79(3):887-92. DOI: 10.1016/j.talanta.2009.05.023
Source: PubMed


We propose a very simple and fast method for detecting Sudan dyes (I, II, III and IV) in commercial spices, based on characterizing samples through their UV-visible spectra and using multivariate classification techniques to establish classification rules. We applied three classification techniques: K-Nearest Neighbour (KNN), Soft Independent Modelling of Class Analogy (SIMCA) and Partial Least Squares Discriminant Analysis (PLS-DA). A total of 27 commercial spice samples (turmeric, curry, hot paprika and mild paprika) were analysed by chromatography (HPLC-DAD) to check that they were free of Sudan dyes. These samples were then spiked with Sudan dyes (I, II, III and IV) up to a concentration of 5 mg L(-1). Our final data set consisted of 135 samples distributed in five classes: samples without Sudan dyes, samples spiked with Sudan I, samples spiked with Sudan II, samples spiked with Sudan III and samples spiked with Sudan IV. Classification results were good and satisfactory using the classification techniques mentioned above: 99.3%, 96.3% and 90.4% of correct classification with PLS-DA, KNN and SIMCA, respectively. It should be pointed out that with SIMCA, there are no real classification errors as no samples were assigned to the wrong class: they were just not assigned to any of the pre-defined classes.

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    • "In multi-class classification, the discriminant approach is followed more frequently than the class-modeling one. A discriminant classification method which has gained increasing attention in the last years is based on partial least squares (PLS) regression, and it is usually referred to as discriminant PLS (D-PLS) or PLS discriminant analysis (PLS-DA) [6] [7] [8]. In the recent years, a number of attempts have been addressed to develop classmodeling techniques exploiting the advantages offered by the PLS method [9] [10] [11] [12]. "
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    Analytica Chimica Acta 12/2014; 851. DOI:10.1016/j.aca.2014.09.013 · 4.51 Impact Factor
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    • "Therefore, numerous spectroscopy techniques have been developed to detect the illegal additives in food products [6]. Anibal and coworkers [7] reported a simple and fast method for detection of Sudan dyes (I, II, III and IV) in commercial spices. In this method, samples were characterized through UV–visible spectra, and then the classification rules were established by using multivariate classification techniques. "
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    ABSTRACT: A highly selective molecularly imprinted solid-phase extraction (MISPE) combined with liquid chromatography-ultraviolet detection was developed for the simultaneous isolation and determination of four Sudan dyes (I, II, III and IV) in egg-yolk products. The imprinted microspheres synthesized by suspension polymerization using phenylamine–naphthol as mimic template show high selectivity and affinity to the four kinds of Sudan dyes and were successfully applied as selective sorbents of solid-phase extraction for the simultaneous determination of the four Sudans from egg-yolk samples. Good linearity was obtained in a range of 0.062–10μgg−1 and the average recoveries of the four Sudans at three spiked levels ranged from 94.1 to 102.5% with the relative standard deviations less than 5.8%. The developed extraction protocol eliminated the effect of template leakage on quantitative analysis and could be applied for the determination of Sudans in complicated food samples. KeywordsColumn liquid chromatography–Molecularly imprinted solid-phase extraction–Imprinted microspheres–Sudan dyes–Egg yolk
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