Pesticide residues in propolis from Spain and Chile. An approach using near infrared spectroscopy

This study analyses the presence of pesticides in 106 samples of raw propolis from Spain and Chile. The components detected and quantified using gas chromatography mass spectrometry were as follows: triamidefon present in 70.1% of the samples with concentrations between 0.35 and 42.17 mg/kg, and dicofol detected in 7.5% of the samples with concentrations between 0.39 and 2.83 mg/kg. Diclorofluanid, procymidone, folpet, propham and metazachlor were also detected but only in a small number of samples. Near infrared spectroscopy with a remote reflectance fibre-optic probe was used to detect samples contaminated with triadimefon via partial least squares discriminant, with a R-2 value of 0.71. In addition, the presence of the pesticide triadimefon in propolis was quantified using the modified partial least squares (MPLS) regression method. The calibration results showed a coefficient of determination (R-2) of 0.81, a root mean square error (RMSE) of 0.36, and a ratio of performance to deviation (RPD) of 2.5.