Pyrrolizidine alkaloids in bee pollen identified by LC-MS/MS analysis and colour parameters using multivariate class modeling

Abstract

Toxic pyrrolizidine alkaloids (PAs) and their N-oxides (PANOs) can be present in bee pollen depending on the plants visited by bees. A liquid chromatography-mass spectrometry (LC-MS/MS) method was developed and validated to monitor 17 PAs/PANOs in 44 bee pollens. The CIE-L*a*b* colour coordinates with the specular component either included or excluded were recorded in pellets and ground aliquots. Lightness (L*) and yellowness (b*) of ground bee pollen were significantly correlated to PAs/PANOs content. The L* and b* cut-offs sorted by a receiver operating characteristic analysis to predict PAs/PANOs presence showed a significant increase in the relative risk to detect amounts higher than 84 μg kg À1 . Two supervised canonical discriminant analyses confirmed that pollen without PAs could be distinguished from those containing PAs/PANOs. The data suggest that instrumental colour coupled with supervised models could be used as a screening test for PAs/PANOs in bee pollen, before the confirmatory LC-MS/MS analysis.

Discriminant analysis of pyrrolizidine alkaloid contamination in bee pollen based on near-infrared data from lab-stationary and portable spectrometers

“…Sample preparation, PA/PANO extraction from bee pollen samples and LC-MS/MS analysis were performed as described by De Jesus Inacio et al [30]. The validated LC-MS/MS method used in this work is suitable for detecting and quantifying 17 PAs/PANOs in bee pollen.…”

“…The validated LC-MS/MS method used in this work is suitable for detecting and quantifying 17 PAs/PANOs in bee pollen. Detailed information on the analytical parameters (specificity, linearity, apparent recovery, precision, absolute recovery and matrix effect) evaluated in the LC-MS/MS method validation for target PAs/PANOs were reported in De Jesus Inacio et al [30].…”

“…The 17 PAs/PANOs were detected by the MS with the ESI source operating in positive-ion mode. The optimised operational LC-ESI(+)-MS/MS and detection conditions used for all the PAs/PANOs were as follows: sheath gas flow, 35 arbitrary units; auxiliary gas flow, six arbitrary units; ion spray voltage, 3.5 kV; capillary temperature, 350 °C; capillary voltage, 11 V; and tube lens, 60 V. The MS/MS conditions (collision energy, precursor and product ions) and the retention times obtained for each analyte were reported in Inacio et al [30].…”

“…The limit of quantification (LOQ) of each PA/PANO was set at 0.4 µg/kg which is the lowest calibrator concentration on the calibration curve that could be quantified with a precision within 20%, and trueness between 80 and 120% as reported by the European Commission Decision 2002/657/ EC [30].…”

“…LC-MS/MS analysis of the 60 dehydrated bee pollen samples was performed according to a validated method published in a previous study [30].…”