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 dataThe 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 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).