Infrared spectroscopy combined with random forest to determine tylosin residues in powdered milk.

The contamination of milk by antibiotic residues is a worldwide health and food safety problem. There is a need to develop new methods for the rapid determination of antibiotic residues in milk. A method has been developed for determining tylosin residues directly in powdered milk using Fourier Transformed Infrared spectroscopy (FTIR). Tylosin is a broad-spectrum macrolide antibiotic. The spectra obtained were submitted to chemometric analysis to obtain a prediction model for tylosin concentration in powdered milk. Using the Boruta algorithm, the absorption bands related to the milk contamination by the antibiotic were identified. Random forest was shown to be adequate for the prediction of tylosin residues in milk at low concentrations (≤ 100 µg L-1) and the prediction model generated showed high correlation and determination coefficients (greater than 0.95). The proposed methodology proved to be efficient for the investigation of antibiotic residues in powdered milk.

Extraction induced by emulsion breaking for As, Se and Hg determination in crude palm oil by vapor generation-AFS.

In this work is presented the development of a method for As and Se determination in crude palm oil samples by hydride generation atomic fluorescence spectrometry and Hg by cold vapor atomic fluorescence spectrometry after ultrasound-assisted emulsification and extraction induced by emulsion breaking (EIEB). The optimization of the method was carried out by multivariate designs. The developed method has presented limits of quantification (LOQ) of 0.72, 0.12, and 1.5 µg L-1 for As, Hg, and Se, respectively. The precisions of the proposed method expressed as repeatability were 0.92, 2.2, and 3.7% RSD for 2 µg L-1 (n = 10) of As, Hg and Se, respectively. The developed methodology was applied in palm oil samples collected in the Bahia State. Concentrations (µg L-1) found in the samples were between