Mid-infrared spectroscopy and chemometric analysis were tested to determine tetracycline’s residues in cow’s milk. Cow’s milk samples (n = 30) were spiked with tetracycline, chlortetracycline, and oxytetracycline in the range… Click to show full abstract
Mid-infrared spectroscopy and chemometric analysis were tested to determine tetracycline’s residues in cow’s milk. Cow’s milk samples (n = 30) were spiked with tetracycline, chlortetracycline, and oxytetracycline in the range of 10–400 μg/l. Chemometric models to quantify each of the tetracycline’s residues were developed by applying Partial Components Regression and Partial Least Squares algorithms. The Soft Independent Modeling of Class Analogy model was used to differentiate between pure milk and milk sample with tetracycline residues. The best models for predicting the levels of these antibiotics were obtained using Partial Least Square 1 algorithm (coefficient of determination between 0.997–0.999 and the standard error of calibration from 1.81 to 2.95). The Soft Independent Modeling of Class Analogy model showed well-separated groups allowing classification of milk samples and milk sample with antibiotics. The obtained results demonstrate the great analytical potential of chemometrics coupled with mid-infrared spectroscopy for the prediction of antibiotic in cow’s milk at a concentration of microgram per litre (μg/l). This technique can be used to verify the safety of the milk rapidly and reliably. Antibiotics, human health, multivariate analysis, chemometrics, vibrational spectral data The tetracyclines (TCs) have a wide antibacterial range and bacteriostatic action, and a good activity against infections caused by a number of bacteria. The TCs are permitted in a diversity of food-producing animals (sheep, poultry, pigs, cattle and fish) (Debuf 1998). The usage of TCs in dairy husbandry and the failure to follow good veterinary practices can lead to unsafe residue concentrations in various tissues and milk, with potential adverse effects on human health (for example allergic reactions in some hypersensitive individuals). Also the TCs residues may affect aquatic ecosystems (Feng-Jiao et al. 2014). To guarantee high quality of human food, several regulatory authorities have defined the maximum residue limits (MRLs) allowing only trace amounts of residues of veterinary drugs in food for human intake. The MRLs are based on the acceptable daily intake of each drug; maximum food intake is also taken into account. The MRLs are established at mg·kg-1 or μg·kg-1. The US Food and Drug Administration (FDA) has set tolerances for the residues of tetracycline, chlortetracycline and oxytetracycline in bovine milk at 300 μg·l-1 (Riviere et al. 2003), whereas in the European Union, the MRL is established at 100 μg·kg-1 (Commission Regulation (EU) No. 37/2010). Avoidance of TC residues is an important focus of the dairy industry. Judicious use of antibiotics, followed by an appropriate milk withholding time and screening for residues are essential aspects of milk quality management for assuring human food safety (Boeckman and Carlson 2006). Consequently, it is important to develop analytical procedures capable of determining the levels of TCs and to evaluate their presence in milk in order to protect human health (Casella and Picerno 2009). ACTA VET. BRNO 2018, 87: 181-188; https://doi.org/10.2754/avb201887020181 Address for correspondence: Tzayhrí Gallardo-Velazquez Instituto Politécnico Nacional Prolongación de Carpio y Plan de Ayala S/N. Col. Santo Tomás C.P. 11340. Ciudad de México, México Phone: +01 55 57 29 60 00 ext. 62305 E-mail: [email protected] http://actavet.vfu.cz/ A number of analytical procedures have been widely used for the quantification of TCs in real matrixes. These include: microbiological assay (Nagel et al. 2011), differential scanning calorimetry (DSC) (Yildiz and Unluturk 2009), capillary electrophoresis (CE) (Ibarra et al. 2011), enzyme-linked immunosorbent assays (ELISA), radioimmunoassays, biosensors and chromatographic techniques, such as high-performance liquid chromatography (HPLC), coupled with different detection systems (Toldrá and Reig 2006), liquid chromatography operating under reverse phase mode (Aderson et al. 2005) and coupled with several detection schemes such as spectrophotometry (Viñas et al. 2004; Andersen et al. 2005; Fritz and Zuo 2007), electrochemical (Casella and Picerno 2009), fluorescence (Pena et al. 2005; Pena et al. 2007; Schneider et al. 2007), or mass spectrometry (Andersen et al. 2005; Pena et al. 2007), among others. The above analytical methods have proven useful in evaluating the concentrations of TCs in milk. Nevertheless, these techniques are difficult, laborious, requiring a significant investment in analysis time and skilled personnel (Toldrá and Reig 2006). Currently, Fourier transform mid-infrared (FTIR) spectroscopy is used to substitute old procedures of analysis. Mid FTIR is fast, requiring only a small sample; no sample preparation or use of solvents are necessary before the analysis. A small number of spectroscopic applications to identify analytes at concentrations of microgram per litre (μg/l) have been demonstrated. Mid-infrared with chemometrics has been useful for the identification of veterinary residues at μg/l concentrations (Sivakesava and Irudayaraj 2002; Dračková et al. 2009; Meza-Márquez et al. 2011; MezaMárquez et al. 2012). Therefore, the aim of this study was use the Mid-FTIR spectroscopy with chemometric analysis to quantify tetracycline, chlortetracycline, and oxytetracycline in cow’s milk at concentrations of μg/l. Materials and Methods
               
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