Development of an Analytical Method for Analyzing Pyrrolizidine Alkaloids in Different Groups of Food by UPLC-MS/MS

Abstract

Suspected nontargeted pyrrolizidine alkaloids (PAs), without analytical reference standard, were observed and interfered with the determination of targeted PAs in complex food matrices, especially for spices samples. Selectivity and applicability of multiple reaction monitoring (MRM) transitions, multistage fragmentation (MS3), and MRM with differential ion mobility spectrometry (DMS) for eliminating false positive identifications were evaluated. Afterward, a selective and sensitive LC-MS/MS method for the determination of 15 PAs and 13 PA N-oxides in foodstuffs was developed. The sample preparation and cleanup are applicable to a wide range of foodstuffs, including cereal products, dairy products, meat, eggs, honey, tea infusion, and spices. Freezing-out of the raw extract and the water/acetonitrile washing steps in a solid phase extraction was found to efficiently remove complex matrices. The method was validated at 0.05 μg kg for general food and 0.5 μg kg for spices, with reference to the Eurachem Guide. The estimated limit of quantifications of different PAs was in the range of 0.010-0.087 μg kg for general food and 0.04-0.76 μg kg for spices. Isotopically labeled PAs were used as internal standards to correct the variation of PAs/PANs performance in different food commodities. Matrix effects observed in complex food matrices could be reduced by solvent dilution. Recoveries of PAs and PA N-oxides were all seen within 50-120%.

Overview of Recent Liquid Chromatography Mass Spectrometry-Based Methods for Natural Toxins Detection in Food Products

“…On the contrary, the use of HRMS technologies, and in particular those using hybrid approaches like Q-Orbitrap or Q-TOF, enables ultra-high resolving power values, and are very promising in the analysis of this class of natural toxins [ 89 ]. Moreover, multistage fragmentation (MS n ) or differential ion mobility mass spectrometry can be considered very helpful in discriminating isobaric compounds [ 90 ]. In June 2015, the European Commission issued the Recommendation (EU) 2015/976 on the monitoring of the presence of TAs in food and on the method of analysis that should preferably be HPLC-MS/MS or, if not possible, GC-MS.…”

“…In another study, a UPLC-MS/MS analytical method was proposed for the determination of 15 PAs and 13 respective N-oxides in different groups of food [ 90 ]. The ultrasonic assisted SLE and the clean-up through the C18 SPE column allowed the application of the method to several matrices including cow milk, tea infusion, honey, cooked chicken, egg, cooked beef, barley flour and clove leaves.…”

Development of UPLC-Q-TOF-MS Coupled with Cation-exchange Solid-phase Extraction Method for the Determination of Ten Pyrrolizidine Alkaloids in Herbal Medicines

“…It was reported that PAs showed a degradation possibility under a high concentration of ammonium hydroxide. 34 Therefore, 3 vol% ammonium hydroxide in methanol was selected as the final optimized elution solvent. Figure 3 shows the total ion chromatograms of PAs extracted from an Emilia sonchifolia sample before and after being treated by SPE.…”

Molecularly imprinted polymer solid‐phase microextraction coupled with ultra high performance liquid chromatography and tandem mass spectrometry for rapid analysis of pyrrolizidine alkaloids in herbal medicine

“…Considering the intoxication of PAs, many researchers have reported the detection of PAs in foodstuffs and herbal plants by using spectrophotometry , HPLC , MEKC , LC‐MS , GC‐MS , etc. Owing to the complexity of matrices, the majority of these reports resorted to at least one or more clean‐up steps to separate and enrich enough amounts of PAs for the analysis.…”