Development and validation of a QuEChERS method coupled to liquid chromatography and high resolution mass spectrometry to determine pyrrolizidine and tropane alkaloids in honey

Paper-immobilized liquid-phase microextraction for direct paper spray mass spectrometry and immuno-detection of atropine in baby food, buckwheat cereals, and edible oils at regulatory levels

BACKGROUND

Atropine is a strictly regulated natural toxin. Monitoring for atropine is thus important, but often expensive and time-consuming. Moreover, the range of relevant matrices, and corresponding differences in required detection limits for atropine vary. Therefore, we developed a more simplified and affordable method, combining immunodetection and mass spectrometry to detect atropine in buckwheat, canola oil, and baby cereals at regulatory levels.

RESULTS

In this method, atropine is selectively enriched on paper using a dual-paper-immobilized liquid-phase microextraction (PI-LPME; enrichment ∼144×). One PI-LPME paper can be directly coupled to a lateral flow immunoassay, for initial screening. In case of a suspect sample, the other PI-LPME paper is transported to a laboratory, where it can be stored at room temperature (recovery >90%, no difference between 1 and 10 days of storage). The PI-LPME paper can then be analyzed with paper spray-(high resolution) mass spectrometry (PS-(HR)MS). Using atropine-d5 as internal standard, the PS-HRMS method could reach detection limits in matrix almost as low as HPLC-HRMS, respectively 1.2-2.7 μg kg-1 and 0.2-1.3 μg kg-1. Furthermore, the accuracy and precision of the PS-HRMS method was comparable to HPLC-HRMS for buckwheat cereals (precision: 8.7%-9.6% vs. 7.6%-10%, accuracy: -4.0%-17% vs. -6.7%-15%) and canola oil (precision: 6.4%-10% vs. 1%-1.8%, accuracy: -12%-7.7% vs. -2.4%-1.9%).

SIGNIFICANCE

Our paper-based workflow has the potential to aid in the fast and affordable monitoring of atropine. Importantly, the method's suitability is demonstrated for diverse matrices, and it is expected that it can be easily adapted to monitor for other food safety hazards - given the wide applicability of liquid-liquid extractions.

Quantitative Analysis of Pyrrolizidine Alkaloids in Food Matrices and Plant-Derived Samples Using UHPLC-MS/MS

Pyrrolizidine alkaloids (PAs) are a class of nitrogen-containing basic organic compounds that are frequently detected in foods and herbal medicines. Owing to their potential hepatotoxic, genotoxic, and carcinogenic properties, PAs have become a significant focus for monitoring global food safety. In this study, an ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method was developed for the detection and analysis of three foods (tea, honey, and milk) susceptible to PA contamination. This optimized method effectively separated and detected three types of PAs, namely, three pairs of isomers and two pairs of chiral compounds. The limits of detection (LODs) and limits of quantification (LOQs) were determined to be 0.015-0.75 and 0.05-2.5 µg/kg, respectively, with the relative standard deviations (RSDs) of both the interday and intraday precisions remaining below 15%. The average PA recoveries from the honey, milk, and tea matrices fell within the ranges of 64.5-103.4, 65.2-112.2, and 67.6-107.6%, respectively. This method was also applied to 77 samples collected from 33 prefecture-level cities across 16 provinces and included 40 tea, 6 milk, 8 honey, 14 spice, and 9 herbal medicine samples. At least one PA was detected in twenty-three of the samples, with herbal medicines exhibiting the highest total PA content. The obtained results indicate that the developed method demonstrated good repeatability and stability in the detection and quantitative analyses of PAs in food- and plant-derived samples. This method is therefore expected to provide reliable technical support for food safety risk monitoring.

Dual-functional probe-based multi-signal immunosensor platform for tropane alkaloids: Verification and evaluation

This study aims to realise rapid detecting of tropane alkaloids (TAs) in food. For this purpose, a broad-spectrum single-chain fragment variable was fused with horseradish peroxidase to create an antibody-enzyme complex (AEC) with antigen recognition and catalytic activity. A multi-signal immunosensor platform based on AEC in the direct competitive reaction mode was constructed using 3,3',5,5'-tetramethylbenzidine and 10-acetyl-3,7-dihydroxyphenoxazine as substrates. The sensitivity of TAs in the immunosensor platform ranged from 0.25 μg/kg to 7912.46 μg/kg. Honey was selected as a representative food sample, and the limit of detection of TAs in honey ranged from 0.02 μg/kg to 409.11 μg/kg, with a recovery rate of 65.7 %-117.1 % and a coefficient of variation less than 21.4 %. Results showed that the immunosensor platform possesses satisfactory accuracy and precision, which highlights its potential for practical applications and its suitability as an ideal tool for rapid screening of TAs in food.

Reports of tropane alkaloid poisonings and analytical techniques for their determination in food crops and products from 2013 to 2023

Food safety is crucial to attaining food security and sustainability. Unsafe foods for human and animal consumption lead to product recalls and rejection, negatively impacting the global economy and trade. Similarly, climate change can adversely affect the availability of safe and nutritious food at the table. The changing climatic conditions and global food trade and transport can make the movement of toxic plants possible, resulting in food crops being increasingly invaded by some species of plants that produce toxic secondary metabolites, such as tropane alkaloids (TAs). Datura stramonium from the Solanaceae plant family is an invasive and virulent plant that produces high amounts of two TAs, atropine and scopolamine. Various food poisoning events following accidental or deliberate ingestion of foods contaminated by atropine and scopolamine from seeds of D. stramonium have been recorded in different locations globally. Due to these incidents, regulatory agencies require the development of plant toxin detection methods that can be used in the food chain as early as possible. This systematic review thus focuses on the TA determination techniques in food and feeds published between 2013 and 2023. A particular focus was given to the sample preparation methods, the improvements of each technique claimed, and data to support the performance of each method, especially the ability to measure at or below the maximum level. The review concludes with other technological advancements, including rapid spectroscopy, electrophoresis, and colorimetric methods, as well as the possibility of coupling with smartphones for use in on-farm detection and the challenges in applying them.

Underexplored food safety hazards of beekeeping products: Key knowledge gaps and suggestions for future research

These days, a growing consumer demand and scientific interest can be observed for nutraceuticals of natural origin, including apiculture products. Due to the growing emphasis on environmental protection, extensive research has been conducted on the pesticide and heavy metal contamination of bee products; however, less attention is devoted on other food safety aspects. In our review, scientific information on the less-researched food safety hazards of honey, bee bread, royal jelly, propolis, and beeswax are summarized. Bee products originating from certain plants may inherently contain phytotoxins, like pyrrolizidine alkaloids, tropane alkaloids, matrine alkaloids, grayanotoxins, gelsemium alkaloids, or tutin. Several case studies evidence that bee products can induce allergic responses to sensitive individuals, varying from mild to severe symptoms, including the potentially lethal anaphylaxis. Exposure to high temperature or long storage may lead to the formation of the potentially toxic 5-hydroxymethylfurfural. Persistent organic pollutants, radionuclides, and microplastics can potentially be transferred to bee products from contaminated environmental sources. And lastly, inappropriate beekeeping practices can lead to the contamination of beekeeping products with harmful microorganisms and mycotoxins. Our review demonstrates the necessity of applying good beekeeping practices in order to protect honeybees and consumers of their products. An important aim of our work is to identify key knowledge gaps regarding the food safety of apiculture products.

Mass spectrometric analysis strategies for pyrrolizidine alkaloids

Pyrrolizidine alkaloids (PAs) in food and natural preparations have received widespread attention due to their hepatotoxicity, genotoxicity, and embryotoxicity. Mass spectrometry (MS), as a high resolution, high sensitive, and high throughput detection tool, has been the most commonly used technique for the determination of PAs. The continuous advancement of new technologies, methods, and strategies in the field of MS has contributed to the improvement of the analytical efficiency and methodological enhancement of PAs. This paper provides an overview of the structure, toxicity properties and commonly employed analytical methods, focusing on the concepts, advances, and novel techniques and applications of MS-based methods for the analysis of PAs. Additionally, the remaining challenges, future perspectives, and trends for PA detection are discussed. This review provides a reference for toxicological studies of PAs, content monitoring, and the establishment of quality control and safety standards for herbal and food products.

UHPLC-Q-TOF analysis of pyrrolizidine alkaloids in North-Macedonian honey

Honey contaminated with pyrrolizidine alkaloids (PAs) could pose a risk for human consumption, being a widely consumed food product. A fast and simple LC/MS method for the analysis of pyrrolizidine alkaloids in honey was optimised to collect occurrence data. The extraction efficiency was evaluated by a systematic study of multiple solvent mixtures and clean-up procedures. The best results for PA extraction were obtained using a formic acid/methanol mixture with subsequent clean-up by the QuEChERS method, resulting in a mean recovery range of 91.8-102%. The method validation showed satisfactory intra-day (RSD < 5.1%) and inter-day precision (RSD < 9.1%). The proposed method was applied to 14 samples. A total of six PAs and two N-oxides were detected, with levels between 89 and 8188 µg/kg. This assessment highlights the potential risk of intoxication and the need for further investigations regarding an effective quality system for manufacturers to control PAs in honey.

Miniaturized Analytical Strategy Based on μ-SPEed for Monitoring the Occurrence of Pyrrolizidine and Tropane Alkaloids in Honey

Currently, the analysis of trace-level contaminants in food must be addressed following green analytical chemistry principles and with a commitment to the sustainable development goals. Accordingly, a sustainable and ecofriendly microextraction procedure based on μ-SPEed followed by ultrahigh liquid chromatography coupled to ion-trap tandem mass spectrometry analysis was developed to determine the occurrence of pyrrolizidine and tropane alkaloids in honey samples. The μ-SPEed procedure took approximately 3 min per sample, using only 100 μL of organic solvent and 300 μL of diluted sample. The method was properly validated (overall recoveries 72-100% and precision RSD values ≤15%), and its greenness was scored at 0.61 out of 1. The method was applied to different honey samples, showing overall contamination levels from 32 to 177 μg/kg of these alkaloids. Atropine was found in all the samples, whereas retrorsine N-oxide, lasiocarpine, echimidine, and echimidine N-oxide were the main pyrrolizidine alkaloids in the samples analyzed.

Pyrrolizidine Alkaloids in Tea (Camellia sinensis L.) from Weeds through Weed-Soil-Tea Transfer and Risk Assessment of Tea Intake

Pyrrolizidine alkaloids (PAs) have been detected in tea and can threaten human health. However, the specific source of PAs in tea is still unclear. Here, 88 dried tea products collected from six major tea-producing areas in Anhui Province, China, were analyzed. The detection frequency was 76%. The content of total PAs in dried tea was between 1.1 and 90.5 μg/kg, which was all below the MRL recommended by the European Union (150 μg/kg). In the Shexian tea garden, PAs in the weeds and weed rhizospheric soil around tea plants and the fresh tea leaves were analyzed. Intermedine (Im), intermedine-N-oxide (ImNO), and jacobine-N-oxide (JbNO) were transferred through the weed-to-soil-to-tea route into the fresh tea leaves; only Im and ImNO were detected in dried tea samples. Potential risk of the total PAs in the tea infusion was assessed according to the margin of exposure method, and it might be a low concern for public health.

Generation of broad-spectrum recombinant antibody and construction of colorimetric immunoassay for tropane alkaloids: Recognition mechanism and application

Tropane alkaloids (TAs) have emerged as plant toxins, related to poisoning events. The development of stable antibodies is crucial to ensure the effectiveness of immunological methods in quickly and accurately monitoring these alkaloids. In this study, based on hybridoma, the variable region gene of monoclonal antibody (mAb) was amplified, and the recombinant antibody (rAb) gene sequence (VH-Linker-VL) was successfully constructed and expressed in HEK293F. The obtained rAb has kept the same performance as mAb, and the IC50 of 29 TAs ranged from 0.12 to 2642.78 ng/mL. In the recognition mechanism, the docking and dynamics model identified hydrophobic interaction as the most critical force. Substituent will impact recognition by influencing the spatial structure and hydrophobic properties. Then, a colorimetric immunoassay based on rAb was established, five types of water and thirty-nine nectars of honey were tested. The results demonstrated the absence of TAs in environmental water, whereas atropine was detected in more than 13.47% of honey samples at concentrations exceeding 1 μg/kg. The results show a good correlation with UHPLC-MS/MS, suggesting that the immunoassay has excellent screening ability. The data on TAs in honey and water could serve as a foundation for developing relevant policies.

Development, validation, and application of a multimatrix UHPLC-MS/MS method for quantification of Datura-type alkaloids in food

A quantitative ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method was developed and validated for the determination of tropane alkaloids (TAs), atropine and scopolamine, in a variety of food products. The sample preparation of cereal-based food, oilseeds, honey, and pulses consisted of a solid-liquid extraction with an acidified mixture of methanol and water, while an additional step of solid-phase extraction on a cation-exchange sorbent was introduced in the treatment of teas and herbal infusions, aromatic herbs, spices and food supplements. The limits of quantification of the method varied from 0.5 to 2.5 µg kg-1. Apparent recovery was in the range of 70-120%, and repeatability and intermediate precision were below 20%. The method was successfully applied in a proficiency testing exercise as well as in the analysis of various commercial foods. Only 26% of the analysed food samples contained one or both TAs. The mean concentrations for atropine and scopolamine amounted to 21.9 and 6.5 µg kg-1, respectively, while the maximum concentrations were 523.3 and 131.4 µg kg-1, respectively. Overall, the highest levels of TA sum were found in an herbal infusion of fennel and a spice mix containing fennel and anise seeds.

QuEChERS method combined to liquid chromatography high-resolution mass spectrometry for the accurate and sensitive simultaneous determination of pyrrolizidine and tropane alkaloids in cereals and spices

Within the last decades, in the EU, there has been an increasing interest in toxic plant alkaloids as food contaminants, especially after the continuous and growing consumption of plant-based foods compared with food of animal origin. In this regard, the once neglected presence of these tropane alkaloids (TAs) and pyrrolizidine alkaloids (PAs) has recently been reconsidered by the European Food Safety Authority, highlighting the lack of data and the need to develop risk assessment strategies. For this reason, the emphasis has been placed on detecting their occurrence in food through the development of accurate and sensitive analytical methods to achieve the determination of these compounds. The present study aims to elaborate and validate an analytical method based on QuEChERS sample preparation approach, exploiting the UHPLC coupled to the HRMS to simultaneously identify and quantify 21 PAs and two TAs in cereals and spices. For TAs, the obtained limit of detection (LOD) is 0.1 μg·kg-1 and the limit of quantification (LOQ) is 0.4 μg·kg-1 , while for PAs, the LODs values ranging between 0.2 to 0.3 μg·kg-1 and the LOQ, between 0.4 and 0.8 μg·kg-1 , ensuring compliance with the recently established European Regulations. Several commercial samples were analysed to further verify the applicability of this comprehensive analytical approach.

Assessment of Toxic Pyrrolizidine and Tropane Alkaloids in Herbal Teas and Culinary Herbs Using LC-Q-ToF/MS

Pyrrolizidine alkaloids are secondary metabolites produced by plants as a defense against insects. These can cause acute or chronic toxicity in humans. Therefore, avoiding potential poisoning from the consumption of tea and culinary plants contaminated with pyrrolizidine alkaloids (PAs), pyrrolizidine alkaloids N-oxides (PANOs), and tropane alkaloids (TAs) is important for human health and food safety. Therefore, it is important to determine the levels of these substances with reliable and highly accurate methods. In this study, the PAs, PANOs, and TAs in herbal teas and culinary herbs sold in Turkish markets were identified and their levels were determined. Thus, the general profiles of herbal teas and culinary herbs in Turkey were revealed, and the compliance of the total amounts of PA and TA with the regulations was examined. The identification and quantification of 25 PAs and N-oxides and 2 TAs (atropine and scopolamine) in the samples was performed with a liquid chromatography-quadrupole time-of-flight tandem mass spectrometer (LC-Q-ToF/MS). At least a few of these substances were detected in all of the tested herbal teas and culinary herbs. The total contents of the black tea, green tea, mixed tea, flavored tea, chamomile tea, sage tea, linden tea, fennel tea, rosehip tea, peppermint, and thyme samples ranged from 4.6 ng g-1 to 1054.5 ng g-1. The results obtained shed light on the importance of analyzing the total dehydro PA, PANO, and TA amounts in plant-based products consumed in diets with sensitive and accurate methods, and they highlight the necessity of performing these analyses routinely in terms of food safety.

Pyrrolizidine Alkaloids in Food on the Italian Market

Pyrrolizidine alkaloids (PAs) are secondary metabolites produced by over 6000 plant species worldwide. PAs enter the food chain through accidental co-harvesting of PA-containing weeds and through soil transfer from the living plant to surrounding acceptor plants. In animal studies, 1,2-unsaturated PAs have proven to be genotoxic carcinogens. According to the scientific opinion expressed by the 2017 EFSA, the foods with the highest levels of PA contamination were honey, tea, herbal infusions, and food supplements. Following the EFSA's recommendations, data on the presence of PAs in relevant food were monitored and collected. On 1 July 2022, the Commission Regulation (EU) 2020/2040 came into force, repealed by Commission Regulation (EU) 2023/915, setting maximum levels for the sum of pyrrolizidine alkaloids in certain food. A total of 602 food samples were collected from the Italian market between 2019 and 2022 and were classified as honey, pollen, dried tea, dried herbal infusions, dried herbs, and fresh borage leaves. The food samples were analyzed for their PA content via an in-house LC-MS/MS method that can detect PAs according to Regulation 2023/915. Overall, 42% of the analyzed samples were PA-contaminated, 14% exceeded the EU limits, and the items most frequently contaminated included dried herbs and tea. In conclusion, the number of food items containing considerable amounts of PAs may cause concern because they may contribute to human exposure, especially considering vulnerable populations-most importantly, children and pregnant women.

Chromatographic Methods for Detection and Quantification of Pyrrolizidine Alkaloids in Flora, Herbal Medicines, and Food: An Overview

Pyrrolizidine alkaloids (PAs) are natural toxins produced by some plants that gained special interest due to their potential hazardous effects in humans and animals. These substances have been found in wild flora, herbal medicines and food products raising health concerns. Recently, maximum concentration levels of PAs were established for some food products; however, maximum daily intake frequently surpasses the upper limit set by the competent authorities posing a health risk. Given the scarcity or absence of occurrence data on PAs in many products, there is an urgent need to measure their levels and establish safety intake levels. Analytical methods have been reported to detect and quantify PAs in different matrices. The commonly used chromatographic methodologies provides accurate and reliable results. Analytical methods include diverse steps as extraction and sample preparation procedures that are critical for sensitivity and selectivity of the analytical method. Great efforts have been directed toward optimization of extraction procedures, clean up and chromatographic conditions to improve recovery, reduce matrix effects, and achieve low limits of detection and quantification. Therefore, this paper aims to give a general overview about the occurrence of PAs in flora, herbal medicines, and foodstuff; and discuss the different chromatographic methodologies used for PAs analysis, namely extraction and sample preparation procedures and chromatographic conditions.

Evaluation of Tropane Alkaloids in Teas and Herbal Infusions: Effect of Brewing Time and Temperature on Atropine and Scopolamine Content

Atropine and scopolamine belong to the tropane alkaloid (TA) family of natural toxins. They can contaminate teas and herbal teas and appear in infusions. Therefore, this study focused on analyzing atropine and scopolamine in 33 samples of tea and herbal tea infusions purchased in Spain and Portugal to determine the presence of these compounds in infusions brewed at 97 °C for 5 min. A rapid microextraction technique (µSPEed^®) followed by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was used to analyze the selected TAs. The results showed that 64% of the analyzed samples were contaminated by one or both toxins. White and green teas were generally more contaminated than black and other herbal teas. Of the 21 contaminated samples, 15 had concentrations above the maximum limit for liquid herbal infusions (0.2 ng/mL) set by Commission Regulation (EU) 2021/1408. In addition, the effects of heating conditions (time and temperature) on atropine and scopolamine standards and naturally contaminated samples of white, green, and black teas were evaluated. The results showed that at the concentrations studied (0.2 and 4 ng/mL), there was no degradation in the standard solutions. Brewing with boiling water (decoction) for 5 and 10 min allowed for higher extraction of TAs from dry tea to infusion water.

The Bright and Dark Sides of Herbal Infusions: Assessment of Antioxidant Capacity and Determination of Tropane Alkaloids

Herbal infusions are highly popular beverages consumed daily due to their health benefits and antioxidant properties. However, the presence of plant toxins, such as tropane alkaloids, constitutes a recent health concern for herbal infusions. This work presents an optimized and validated methodology based on the QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) extraction procedure followed by Ultra-High Performance Liquid Chromatography combined with Time-of-Flight Mass Spectrometry (UHPLC-ToF-MS) for the determination of tropane alkaloids (atropine, scopolamine, anisodamine, and homatropine) in herbal infusions, in accordance with criteria established by Commission Recommendation EU No. 2015/976. One of the seventeen samples was contaminated with atropine, exceeding the current European regulation regarding tropane alkaloids. In addition, this study evaluated the antioxidant capacity of common herbal infusions available on Portuguese markets, indicating the high antioxidant capacity of yerba mate (Ilex paraguariensis), lemon balm (Melissa officinalis), and peppermint (Mentha x piperita).

Target and suspect screening of pesticide residues in soil samples from peach orchards using liquid chromatography quadrupole time-of-flight mass spectrometry

Agricultural soil contamination by pesticide residues has become a serious issue of increasing concern due to their high persistence and toxicity to non-target species. However, as the world's largest peach producer, national scale surveys on pesticide residues in peach orchard soils are scarce in China. In this study, a target and suspect screening method covering over 200 pesticides commonly used in peach orchards was developed using ultra-high performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry in MS^E. An identification strategy using different data processing parameters was developed to identify the pesticide occurrence in soil. The method was applied to soil samples from typical peach orchards in 12 regions across China. The present work also discusses in detail the frequency of occurrence, concentration of pesticides, spatial distribution of multiresidues, and relationship between pesticide occurrence and soil properties. In the tested soil samples, 21 herbicides (level 1), 31 fungicides (level 2a), 24 insecticides (level 2a), and 3 growth regulators (level 2a) were identified. The total concentrations of quantifiable herbicides in the soil samples ranged from 1.05 to 327 ng/g. Only in 5.4% of the soil samples, no pesticide residues were present. By contrast, more than 86% of the total contained multiple residues. This study represents the first large-scale survey of pesticides in soil from peach orchards and provides comprehensive and accurate information on the pesticide residue status for risk assessment.

Pyrrolizidine-producing weeds in tea gardens as an indicator of alkaloids in tea

Pyrrolizidine alkaloids (PAs) can be transferred between plants via soil. Indicators of PAs in tea products are useful for tea garden management. In the present work a total of 37 weed species, 37 weed rhizospheric soils and 24 fresh tea leaf samples were collected from tea gardens, in which PAs were detected in 35 weeds species, 21 soil samples and 10 fresh tea leaves samples. In Shexian tea garden, 12.9 μg/kg of intermedine (Im) in one bud plus three leaves, 1.40 and 14.6 μg/kg of intermedine-N-oxide (ImNO) in one bud plus two leaves and one bud plus three leaves were detected, which were transferred from the PA-producing weeds via soil. However, no PAs were detected in fresh tea leaves collected from Langxi tea garden. The results indicated that synthesis of PAs in weeds and their transfer through the weed-soil-fresh tea leaf route varied with soil environments in different tea gardens.

Development of a Novel LC-MS/MS Multi-Method for the Determination of Regulated and Emerging Food Contaminants Including Tenuazonic Acid, a Chromatographically Challenging Alternaria Toxin

The regulation of food contaminants in the European Union (EU) is comprehensive, and there are several compounds in the register or being added to the recommendation list. Recently, European standard methods for analysis have also been issued. The quick analysis of different groups of analytes in one sample requires a number of methods and the simultaneous use of various instruments. The aim of the present study was to develop a method that could analyze several groups of food contaminants: in this case, 266 pesticides, 12 mycotoxins, 14 alkaloid toxins, and 3 Alternaria toxins. The main advantage of the herein described approach over other methods is the simultaneous analysis of tenuazonic acid (TEA) and other relevant food contaminants. The developed method unites the newly published standard methods such as EN 15662:2018, EN 17194:2019, EN 17256:2019, EN 17425:2021, EN 17521:2021, which describes the analysis of both regulated and emerging contaminants. The developed method is based on a QuEChERS sample preparation, followed by LC-MS/MS analysis under alkaline mobile phase conditions. The pH of the aqueous eluent was set to 8.3, which resulted in baseline separation among ergot alkaloids and their corresponding epimers, a symmetric chromatographic peak shape for analyzing TEA and fit-for-purpose sensitivity for MS/MS detection in both positive and negative ionization modes. Those compounds, which possess the corresponding isotopically labeled internal standards (ISTD), allowed for direct quantification by the developed method and no further confirmation was necessary. This was proven by satisfactory analyses of a number of quality control (QC), proficiency test (PT), and validation samples.

Emerging Issues on Tropane Alkaloid Contamination of Food in Europe

The occurrence of tropane alkaloids (TAs), toxic plant metabolites, in food in Europe was studied to identify those TAs in food most relevant for human health. Information was extracted from the literature and the 2016 study from the European Food Safety Authority. Calystegines were identified as being inherent TAs in foods common in Europe, such as Solanum tuberosum (potato), S. melongena (eggplant, aubergine), Capsicum annuum (bell pepper) and Brassica oleracea (broccoli, Brussels sprouts). In addition, some low-molecular-weight tropanes and Convolvulaceae-type TAs were found inherent to bell pepper. On the other hand, atropine, scopolamine, convolvine, pseudotropine and tropine were identified as emerging TAs resulting from the presence of associated weeds in food. The most relevant food products in this respect are unprocessed and processed cereal-based foods for infants, young children or adults, dry (herbal) teas and canned or frozen vegetables. Overall, the occurrence data on both inherent as well as on associated TAs in foods are still scarce, highlighting the need for monitoring data. It also indicates the urge for food safety authorities to work with farmers, plant breeders and food business operators to prevent the spreading of invasive weeds and to increase awareness.

Development and Validation of an UHPLC-MS/MS Method for the Determination of 32 Pyrrolizidine Alkaloids in Chinese Wild Honey

BACKGROUND

Studies on pyrrolizidine alkaloid (PA) contamination in honey produced in China are scarce. Previously reported HPLC-MS/MS methods for the determination of PAs in honey often suffer from insufficient separation and uncertainties in PA isomers.

OBJECTIVE

To develop and validate an Ultra-HPLC (UHPLC)-MS/MS method for baseline separation of PA isomers towards precise determination of 32 PAs in Chinese wild honey.

METHODS

PAs were extracted from honey samples and separated on an ACQUITY BEH C18 (2.1 mm × 100 mm, 1.7 µm) column with (A) 0.1% formic acid aqueous solution containing 5 mM ammonium acetate and (B) methanol as mobile phase. The column temperature was maintained at 30°C, and flow rate was 0.3 mL/min. Detection was performed by tandem mass spectrometry. The total run time was reduced to 18 min.

RESULTS

Thirty-one of 32 PAs were baseline separated efficiently within 18 min. The LOD and LOQ were 0.06-0.25 µg/kg and 0.22-0.82 µg/kg, respectively, except for that of clivorine, for which LOD and LOQ were 2.03 and 6.78 µg/kg, respectively. The average recoveries ranged between 66.3 and 95.1% and the average RSDs were 3.2 to 8%. The established method was used to analyze PAs in 22 types of Chinese wild honey, and the predominant PAs found in these honey samples were intermedine and lycopsamine.

CONCLUSION

A high-throughput method for the determination of isomeric PAs in honey was developed and validated. Five of the 22 types of Chinese wild honey were contaminated with PAs concentrations of 2.2-207.0 µg/kg.

HIGHLIGHTS

A new method capable of monitoring more PAs and providing better separation than previously reported protocols for the determination of multiclass PAs in honey is established.

Pyrrolizidine Alkaloid Extraction and Analysis: Recent Updates

Pyrrolizidine alkaloids are natural secondary metabolites that are mainly produced in plants, bacteria, and fungi as a part of an organism's defense machinery. These compounds constitute the largest class of alkaloids and are produced in nearly 3% of flowering plants, most of which belong to the Asteraceae and Boraginaceae families. Chemically, pyrrolizidine alkaloids are esters of the amino alcohol necine (which consists of two fused five-membered rings including a nitrogen atom) and one or more units of necic acids. Pyrrolizidine alkaloids are toxic to humans and mammals; thus, the ability to detect these alkaloids in food and nutrients is a matter of food security. The latest advances in the extraction and analysis of this class of alkaloids are summarized in this review, with special emphasis on chromatographic-based analysis and determinations in food.

Multi-template imprinted solid-phase microextraction coupled with UPLC-Q-TOF-MS for simultaneous monitoring of ten hepatotoxic pyrrolizidine alkaloids in scented tea

Pyrrolizidine alkaloids (PAs) are a series of ubiquitous natural toxins in flowering plants, which are associated with serious hepatic disease in humans. However, the simultaneously fast and sensitive monitoring of different PAs are still challenge because of the diversity of PAs and huge amount of interference in complex samples, such as scented tea samples. In this study, molecularly imprinted solid phase microextraction (MIP-SPME) fibers were fabricated by using multi-template imprinting technique for selective recognition and efficient enrichment of different PAs from scented teas. MIP-SPME could be used for selective adsorption of ten types of PAs through specific recognition cavity and strong ionic interaction, including senecionine, lycopsamine, retrorsine, heliotrine, lasiocarpine, monocrotaline, echimidine, erucifoline, europine and seneciphylline. The extraction parameters were also optimized including extraction time, elution solvent and elution time. Then, ultra performance liquid chromatography- quadrupole-time of flight mass spectrometry (UPLC-Q-TOF-MS) coupled with MIP-SPME method was developed for fast, simple, sensitive and accurate determination of ten PAs in scented teas. The established method was validated and presented satisfactory accuracy and high precision. It was also successfully applied for simultaneous determination of ten PAs in different scented tea samples. PAs were found in most of these scented tea samples, which suggest the cautious use of scented tea for consumers.

Effective Solid Phase Extraction of Toxic Pyrrolizidine Alkaloids from Honey with Reusable Organosilyl-Sulfonated Halloysite Nanotubes

Pyrrolizidine alkaloids are plant secondary metabolites that have recently attracted attention as toxic contaminants in various foods and feeds as they are often harvested by accident. Furthermore, they prove themselves as hard to analyze due to their wide structural range and low concentration levels. However, even low concentrations show toxic behavior in the form of chronic liver diseases and possible carcinogenicity. Since sample preparation for this compound group is in need of more green and sustainable alternatives, modified halloysite nanotubes present an interesting approach. Based on the successful use of sulfonated halloysite nanotubes as inexpensive, easy-to-produce cation exchangers for solid phase extraction in our last work, this study deals with the further modification of the raw nanotubes and their performance in the solid phase extraction of pyrrolizidine alkaloids. Conducting already published syntheses of two organosilyl-sulfonated halloysite nanotubes, namely HNT-PhSO3H and HNT-MPTMS-SO3H, both materials were used as novel materials in solid phase extraction. After the optimization of the extraction protocol, extractions of aqueous pyrrolizidine alkaloid mixtures showed promising results with recoveries ranging from 78.3% to 101.3%. Therefore, spiked honey samples were extracted with an adjusted protocol. The mercaptopropyl-sulfonated halloysite nanotubes revealed satisfying loading efficiencies and recoveries. Validation was then performed, which displayed acceptable performance for the presented method. In addition, reusability studies using HNT-MPTMS-SO3H for solid phase extraction of an aqueous pyrrolizidine alkaloid mixture demonstrated excellent results over six cycles with no trend of recovery reduction or material depletion. Therefore, organosilyl-sulfonated halloysite nanotubes display a green, efficient and low-cost alternative to polymeric support in solid phase extraction of toxic pyrrolizidine alkaloids from complex honey matrix.

Improved Analytical Approach for Determination of Tropane Alkaloids in Leafy Vegetables Based on µ-QuEChERS Combined with HPLC-MS/MS

This work presents an optimized methodology based on the miniaturization of the original QuEChERS (μ-QuEChERS) followed by liquid chromatography coupled to mass spectrometry (HPLC-MS/MS) for the determination of tropane alkaloids (TAs), atropine, and scopolamine in leafy vegetable samples. The analytical methodology was successfully validated, demonstrating quantitation limits (MQL) ≤ 2.3 ng/g, good accuracy, and precision, with recoveries between 90–100% and RSD ≤ 13% for both analytes. The method was applied to the analysis of TA-producing plants (Brugmansia versicolor, Solandra maxima, and Convolvulus arvensis). High concentrations of scopolamine were found in flowers (1771 mg/kg) and leaves (297 mg/kg) of B. versicolor. The highest concentration of atropine was found in flowers of S. maxima (10.4 mg/kg). Commercial mixed leafy vegetables contaminated with B. versicolor and S. maxima were analysed to verify the efficacy of the method, showing recoveries between 82 and 110% for both analytes. Finally, the method was applied to the analysis of eighteen samples of leafy vegetables, finding atropine in three samples of mixed leafy vegetables, with concentrations of 2.7, 3.2, and 3.4 ng/g, and in nine samples with concentrations ≤MQL. In turn, scopolamine was only found in a sample of chopped Swiss chard with a concentration ≤MQL.

Sulfonated halloysite nanotubes as a novel cation exchange material for solid phase extraction of toxic pyrrolizidine alkaloids

Pyrrolizidine alkaloids are phytochemicals, which present a highly toxic class of compounds in multiple food resources and are therefore a late-breaking topic in food safety. This study describes the first use of modified halloysite nanotubes as a novel solid material for solid phase extraction. As a result of a fast one-pot sulfonation of the cheap and non-toxic halloysite nanotubes, an efficient cation exchange phase has been prepared. After optimization of the solid phase extraction protocol, high extraction efficiencies and overall recoveries were obtained for a mixture of four pyrrolizidine alkaloid structures through UHPLC-MS/MS analysis with caffeine as the internal standard. Furthermore, the novel solid phase was used for the selective binding of the toxic pyrrolizidine alkaloids in a real-life honey sample, which itself is often contaminated with these compounds. In-house validation showed great extraction efficiencies up to 99.9% for senecionine with a lower limit for lycopsamine with 59.3%, which indicated high selectivity even in the presence of potential interfering compounds. Subsequently, overall recoveries up to 91.5% could be obtained for senecionine while the lowest value was reached for lycopsamine with 55.1%. Comparison with a commercial strong cation exchange tube procedure showed the high competitiveness of the novel solid phase with respect to overall performance. Only slight disadvantages regarding precision and repeatability with values under 5.7% and 11.6% could be observed. Therefore, sulfonated halloysite nanotubes present themselves as an easy to prepare, cheap and highly efficient novel cation exchange material for the selective solid phase extraction of toxic pyrrolizidine alkaloids in frequently contaminated real-life samples like honey.

Nanoflow liquid chromatography mass spectrometry method for quantitative analysis and target ion screening of pyrrolizidine alkaloids in honey, tea, herbal tinctures, and milk

A method for the determination of pyrrolizidine alkaloids in tea, honey, herbal tinctures, and milk samples was developed by employing nano-LC-MS with high-resolution Orbitrap mass spectrometry. Quantitation was performed using the available analytical standards, and a MS² target ion screening approach was developed using fragment ions that were specific for pyrrolizidine alkaloids under collision-induced dissociation. Proof of concept was delivered for the screening approach, proposing that the C₆H₈N⁺ fragment ion is a highly selective fragment ion for the detection of potential pyrrolizidine alkaloids. The elaborated quantitation was applied for the occurrence study of pyrrolizidine alkaloids in food products available on the Latvian market, including samples of tea (n = 15), honey (n = 40), herbal tinctures (n = 15), and milk (n = 10). The median LOQ over all analytes was 0.33 µg kg^-1 in honey, 3.6 µg kg^-1 in tea, 3.3 µg kg^-1 in herbal tinctures, and 0.32 µg kg^-1 in milk. The herbal tinctures samples and milk samples did not contain pyrrolizidine alkaloids above LOQ values. Analytes were detected in 33% of honey and 47% of tea samples. Most common were echimidine, intermedine, and enchinatine N-oxide. Pyrrolizidine alkaloids in tea samples were mainly N-oxides, with the highest total concentration being 215 µg kg^-1 among the samples, exceeding the maximum limit of 200 µg kg^-1 set by Commission Regulation (EU) 2020/2040. In honey samples, lycopsamine-type alkaloids were detected most frequently, with the highest total concentration equal to 74 µg kg^-1. Advantages of the developed nano-LC-MS methods included increased sensitivity in comparison with conventional flow LC-MS, low solvent consumption typical with nano-LC and the novel use of a selective common target ion for detection and discovery of potential pyrrolizidine alkaloids using high resolution mass spectrometry.

Simultaneous Determination of Pyrrolizidine and Tropane Alkaloids in Honey by Liquid Chromatography-mass Spectrometry

Introduction

Pyrrolizidine alkaloids (PAs) and tropane alkaloids (TAs) are natural contaminants of honey and respectively hepatoxic and neurotoxic compounds. Because honey is a popular constituent of the human diet, it is relevant to warrant the safety of the product. For that reason, a method for simultaneous determination of PAs and TAs in honey based on liquid chromatography- mass spectrometry was developed.

Material and Methods

The analytical protocol used sulphuric acid extraction and solid-phase extraction purification. The developed procedure was subjected to validation in terms of linearity, selectivity, repeatability, reproducibility, limits of quantification and determination, matrix effect and uncertainty. A total of 29 honey samples were analysed for the determination of PAs and TAs.

Results

All the evaluated validation parameters fulfilled the requirements of European Commission Decision 2002/657/EC. At least one of the monitored alkaloids was determined in 52% of the samples. Among the most abundant alkaloids were echimidine, intermedine and lycopsamine. The total PA concentrations ranged from 2.2 to 147.0 μg kg^-1. Contrastingly, none of the monitored TAs was detected in the analysed samples. An assessment of the dietary exposure to PAs from the consumption of the contaminated honeys showed that three of them would pose a risk to consumers, especially if they were children.

Conclusion

A sensitive method suitable for simultaneous determination of PAs and TAs in honey was developed and validated. The analysis of 29 honey samples for PAs and TAs revealed that honey destined for retail could pose a risk to consumers.

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

Natural toxins include a wide range of toxic metabolites also occurring in food and products, thus representing a risk for consumer health. In the last few decades, several robust and sensitive analytical methods able to determine their occurrence in food have been developed. Liquid chromatography mass spectrometry is the most powerful tool for the simultaneous detection of these toxins due to its advantages in terms of sensitivity and selectivity. A comprehensive review on the most relevant papers on methods based on liquid chromatography mass spectrometry for the analysis of mycotoxins, alkaloids, marine toxins, glycoalkaloids, cyanogenic glycosides and furocoumarins in food is reported herein. Specifically, a literature search from 2011 to 2021 was carried out, selecting a total of 96 papers. Different approaches to sample preparation, chromatographic separation and detection mode are discussed. Particular attention is given to the analytical performance characteristics obtained in the validation process and the relevant application to real samples.

Isolation of Echimidine and Its C-7 Isomers from Echium plantagineum L. and Their Hepatotoxic Effect on Rat Hepatocytes

Echimidine is the main pyrrolizidine alkaloid of Echium plantagineum L., a plant domesticated in many countries. Because of echimidine’s toxicity, this alkaloid has become a target of the European Food Safety Authority regulations, especially in regard to honey contamination. In this study, we determined by NMR spectroscopy that the main HPLC peak purified from zinc reduced plant extract with an MS [M + H]+ signal at m/z 398 corresponding to echimidine (1), and in fact also represents an isomeric echihumiline (2). A third isomer present in the smallest amount and barely resolved by HPLC from co-eluting (1) and (2) was identified as hydroxymyoscorpine (3). Before the zinc reduction, alkaloids (1) and (2) were present mostly (90%) in the form of an N-oxide, which formed a single peak in HPLC. This is the first report of finding echihumiline and hydroxymyoscorpine in E. plantagineum. Retroanalysis of our samples of E. plantagineum collected in New Zealand, Argentina and the USA confirmed similar co-occurrence of the three isomeric alkaloids. In rat hepatocyte primary culture cells, the alkaloids at 3 to 300 µg/mL caused concentration-dependent inhibition of hepatocyte viability with mean IC50 values ranging from 9.26 to 14.14 µg/mL. Our discovery revealed that under standard HPLC acidic conditions, echimidine co-elutes with its isomers, echihumiline and to a lesser degree with hydroxymyoscorpine, obscuring real alkaloidal composition, which may have implications for human toxicity.

Application of the QuEChERS Strategy as a Useful Sample Preparation Tool for the Multiresidue Determination of Pyrrolizidine Alkaloids in Food and Feed Samples: A Critical Overview

The identification of concerning high levels of pyrrolizidine alkaloids (PAs) in a wide variety of food products has raised the occurrence of these natural toxins as one of the main current issues of the food safety field. Consequently, a regulation with maximum concentration levels of these alkaloids has recently been published to monitor their occurrence in several foodstuffs. According to legislation, the analytical methodologies developed for their determination must include multiresidue extractions with high selectivity and sensitivity, as a set of 21 + 14 PAs should be simultaneously monitored. However, the multiresidue extraction of these alkaloids is a difficult task due to the high complexity of food and feed samples. Accordingly, although solid-phase extraction is still the technique most widely used for sample preparation, the QuEChERS method can be a suitable alternative for the simultaneous determination of multiple analytes, providing green extraction and clean-up of samples in a quick and cost-effective way. Hence, this review proposes an overview about the QuEChERS concept and its evolution through different modifications that have broadened its applicability over time, focusing mainly on its application regarding the determination of PAs in food and feed, including the revision of published works within the last 11 years.

Natural plant toxins in honey: An ignored threat to human health

Consumers often believe that "natural food" is harmless, however naturally occurring toxins in food represent a health risk to humans. Honey as a natural, nutritious sweetener, is one of the most commonly consumed foods throughout the world. However, food safety concerns for honey arise when honeybees collect nectar from poisonous plants such as Rhododendron sp., Coriaria arborea, and Tripterygium wilfordii Hook F. Such honey contains natural plant toxins. Humans may develop intoxication symptoms after consuming toxic honey; in some cases, it can be fatal. As a result, toxic honey poses an often-ignored threat to public health. Typical plant toxins such as grayanotoxins, triptolides, tutin and pyrrolizidine alkaloids, have been identified in toxic honey. Although different toxic honeys elicit similar symptoms, such as vomiting, nausea, and dizziness, the mechanism of toxicity may be different. Thus, it is necessary to determine the exact toxicity mechanism of different toxins to further develop effective antidotes and cures. Another important challenge is preventing toxic honey from entering the food chain. Liquid chromatography-mass spectrometry has a wide range of applications in the detection of different toxins due to its accuracy and simplicity. More methods, however, are urgently needed to detect multiple plant-derived toxins in honey and its derivatives. Developing uniform international standards for toxin detection during quarantine using advanced techniques is critical for preventing human consumption of toxic honey.

Occurrence and Chemistry of Tropane Alkaloids in Foods, with a Focus on Sample Analysis Methods: A Review on Recent Trends and Technological Advances

Tropane alkaloids (TAs) are natural toxins produced by different plants, mainly from the Solanaceae family. The interest in TAs analysis is due to the serious cases of poisoning that are produced due to the presence of TA-producing plants in a variety of foods. For this reason, in recent years, different analytical methods have been reported for their control. However, the complexity of the matrices makes the sample preparation a critical step for this task. Therefore, this review has focused on (a) collecting the available data in relation to the occurrence of TAs in foods for human consumption and (b) providing the state of the art in food sample preparation (from 2015 to today). Regarding the different food categories, cereals and related products and teas and herbal teas have been the most analyzed. Solid-liquid extraction is still the technique most widely used for sample preparation, although other extraction and purification techniques such as solid-phase extraction or QuEChERS procedure, based on the use of sorbents for extract or clean-up step, are being applied since they allow cleaner extracts. On the other hand, new materials (molecularly imprinted polymers, mesostructured silica-based materials, metal-organic frameworks) are emerging as sorbents to develop effective extraction and purification methods that allow lower limits and matrix effects, being a future trend for the analysis of TAs.

Fluorescence-based immunochromatographic test strip for the detection of hyoscyamine

Hyoscyamine (HSM), which acts as an antagonist of the acetylcholine muscarinic receptor and can induce a variety of distinct toxic syndromes in mammals (anti-cholinergic poisoning), is hazardous to human health. Therefore, it is urgent to develop a rapid, sensitive, and cost-effective method to determine HSM. A fluorescent microsphere based immunochromatographic assay was developed for this analyte and gold nanoparticles (AuNPs) were used as a comparison. A monoclonal antibody against HSM was prepared with a 50% inhibition concentration (IC₅₀) of 1.17 ng mL^-1, with no cross-reactivity with five drugs. Under optimized conditions, the cut off limits using the fluorescence-labeled monoclonal antibody strips were 10 ng mL^-1 in 0.01 M PBS and 20 ng mL^-1 in pork, pig urine, and honey samples, and the assay could be completed within 10 min. In comparison with a AuNP immunochromatographic assay, the developed method offered a higher coupling rate and lower amounts of antibodies. This approach could be used for simple, sensitive and rapid screening, and is suitable for on-site screening applications.

Study of the occurrence of toxic alkaloids in forage grass by liquid chromatography tandem mass spectrometry

The toxic alkaloids in forage grass present a serious health hazard to humans and livestock, especially ergot alkaloids (EAs), pyrrolizidine alkaloids (PAs) and tropane alkaloids (TAs). Hence, there is a need for a simultaneous method that allows these dangerous plant toxins to be determined. A simple and effective method was developed to determine fifteen toxic alkaloids (EAs, PAs and TAs) in forage grass using the QuEChERS method and liquid chromatography tandem mass spectrometry (LC-MS/MS). The developed method was validated with average recoveries ranging from 63.10 to 102.10%, and relative standard deviations lower than or equal to 6.39% were obtained. Good linearity over the concentration range of 10-600 µg/kg dry matter (DM) was observed for the target alkaloids. The determination coefficients R² calculated for each of the matrix calibration curves were greater than 0.99. The limits of detection and quantification were 5 µg/kg DM and 10 µg/kg DM, respectively. The reproducibility of the method was verified in three laboratories: all of the mean recoveries of 15 alkaloids were higher than 60%, and the relative standard deviations in alkaloids between laboratories were all less than 14.24%. The proposed method was applied to analyse 134 forage grass samples from the meadow steppe of Inner Mongolia to monitor toxic alkaloids. A significant difference in the frequency of contamination was found between different herbage species and different regions.

High resolution mass spectrometry workflow for the analysis of food contaminants: Application to plant toxins, mycotoxins and phytoestrogens in plant-based ingredients

An analytical workflow including mass spectral library, generic sample preparation, chromatographic separation, and analysis by high-resolution mass spectrometry (HRMS) was developed to gain insight into the occurrence of plant toxins, mycotoxins and phytoestrogens in plant-based food. This workflow was applied to 156 compounds including 90 plant toxins (pyrrolizidine alkaloids, tropane alkaloids, glycoalkaloids, isoquinoline alkaloids and aristolochic acids), 54 mycotoxins (including ergot alkaloids and Alternaria toxins) and 12 phytoestrogens (including isoflavones, lignans and coumestan) in plant-based protein ingredients, cereal and pseudo-cereal products. A mass spectral library was built based on fragmentation spectra collected at 10 different collision energies in both positive and negative ionisation modes for each toxin. Emphasis was put on a generic QuEChERS-like sample preparation followed by ultra-high-pressure liquid chromatography using alkaline mobile phase allowing the separation of more than 50 toxic pyrrolizidine alkaloids. HRMS acquisition comprised a full-scan event for toxins detection followed by data-dependent MS2 for toxin identification against mass spectrum. Method performance was evaluated using fortified samples in terms of sensitivity, repeatability, reproducibility and recovery. All toxins were positively identified at levels ranging from 1 µg kg-1 to 100 µg kg-1. Quantitative results obtained by a standard addition approach met SANTE/12682/2019 criteria for 132 out of 156 toxins. Such a workflow using generic, sensitive and selective multi-residue method allows a better insight into the occurrence of regulated and non-regulated toxins in plant-based foods and to conduct safety evaluation and risk assessments when needed.

Fluorescent lateral flow immunoassay based on gold nanocluster for detection of pyrrolizidine alkaloids

An ultrasensitive and rapid fluorescent immunoassay based on a broad-spectrum monoclonal antibody (mAb) was developed to detect pyrrolizidine alkaloids (PAs) in honey samples. First, Discovery Studio software was used to analyze and predict the target hapten, and retrorsine (RTS) was selected to react with succinic anhydride (HS) for hapten synthesization. A sensitive and broad-spectrum monoclonal antibody (mAb 13E1) was obtained for nine PAs. Then, fluorescent gold nanoclusters (AuNCs) were conjugated with mAb as a label probe and used in establishing a qualitative and quantitative lateral flow immunoassay (AuNCs-LFIA) for the determination of four PAs (retrorsine, platyphylline, senecionine, integerrimine) in honey within 14 min. The limits of detection (LOD) were 0.083 μg/kg. The recovery in spiked honey samples were 87.98-119.57%, with coefficients of variation of ≤ 11.5%. A total of 45 commercial import honey samples from nine different countries were tested through AuNCs-LFIA and UPLC-MS/MS method, and satisfactory consistency (R2 = 0.995) was obtained. The rates of positive samples were 55.56% (25/45), and the average concentrations of four PAs were 3.24-46.47 μg/kg. This ultrasensitive multi-PA method provides an alternative analytical tool for evaluating the human risk posed by the consumption of PA-contaminated honey.

An essay on ecosystem availability of Nicotiana glauca graham alkaloids: the honeybees case study

BACKGROUND

Invasive plant species pose a significant threat for fragile isolated ecosystems, occupying space, and consuming scarce local resources. Recently though, an additional adverse effect was recognized in the form of its secondary metabolites entering the food chain. The present study is elaborating on this subject with a specific focus on the Nicotiana glauca Graham (Solanaceae) alkaloids and their occurrence and food chain penetrability in Mediterranean ecosystems. For this purpose, a targeted liquid chromatography electrospray tandem mass spectrometric (LC-ESI-MS/MS) analytical method, encompassing six alkaloids and one coumarin derivative, utilizing hydrophilic interaction chromatography (HILIC) was developed and validated.

RESULTS

The method exhibited satisfactory recoveries, for all analytes, ranging from 75 to 93%, and acceptable repeatability and reproducibility. Four compounds (anabasine, anatabine, nornicotine, and scopoletin) were identified and quantified in 3 N. glauca flowers extracts, establishing them as potential sources of alien bio-molecules. The most abundant constituent was anabasine, determined at 3900 μg/g in the methanolic extract. These extracts were utilized as feeding treatments on Apis mellifera honeybees, resulting in mild toxicity documented by 16-18% mortality. A slightly increased effect was elicited by the methanolic extract containing anabasine at 20 μg/mL, where mortality approached 25%. Dead bees were screened for residues of the N. glauca flower extracts compounds and a significant mean concentration of anabasine was evidenced in both 10 and 20 μg/mL treatments, ranging from 51 to 92 ng/g per bee body weight. Scopoletin was also detected in trace amounts.

CONCLUSIONS

The mild toxicity of the extracts in conjunction with the alkaloid and coumarin residual detection in bees, suggest that these alien bio-molecules are transferred within the food chain, suggesting a chemical invasion phenomenon, never reported before.

Pyrrolizidine alkaloids and beehive products: A review

Pyrrolizidine alkaloids (PA) are secondary metabolites of plants, which are mostly found in the genus Senecio, Echium, Crotalaria, and Eupatorium. The presence of 1,2-unsaturated PA in foods is a concern to food regulators around the world because these compounds have been associated to acute and chronic toxicity, mainly in the liver. The intake foods with PA/PANO usually occur through accidental ingestion of plants and their derivatives, besides to products of vegetal-animal origin, such as honey. PA/PANO are transferred to honey by their presence in nectar, honeydew, and pollen, which are collected from the flora by bees. In addition to honey, other beekeeping products, such as pollen, royal jelly, propolis, and beeswax, are also vulnerable to PA contamination. In this context, this review provides information about chemical characteristics, regulation, and toxicity, as well as summarizes and critically discusses scientific publications that evaluated PA in honeys, pollens, royal jelly, and propolis.

Technical Overview of Orbitrap High Resolution Mass Spectrometry and Its Application to the Detection of Small Molecules in Food (Update Since 2012)

Food safety and quality issues are becoming increasingly important and attract much attention, requiring the development of better analytical platforms. For example, high-resolution (especially Orbitrap) mass spectrometry simultaneously offers versatile functions such as targeted/non-targeted screening while providing qualitative and quantitative information on an almost unlimited number of analytes to facilitate routine analysis and even allows for official surveillance in the food field. This review covers the current state of Orbitrap mass spectrometry (OMS) usage in food analysis based on research reported in 2012-2019, particularly highlighting the technical aspects of OMS application and the achievement of OMS-based screening and quantitative analysis in the food field. The gained insights enhance our understanding of state-of-the-art high-resolution mass spectrometry and highlight the challenges and directions of future research.

Simultaneous quantification of three tropane alkaloids in goji berries by cleanup of the graphene/hexagonal boron nitride hybrids and ultra-high-performance liquid chromatography tandem mass spectrometry

A modified quick, easy, cheap, effective, rugged and safe method was established for simultaneous determination of atropine, anisodamine, and scopolamine in goji berries by using ultra-high-performance liquid chromatography with tandem mass spectrometry. The graphene/hexagonal boron nitride hybrids were prepared and first applied as a cleanup adsorbent. Compared to classical cleanup adsorbent (C₁₈ ), the graphene/hexagonal boron nitride hybrids as adsorbent had better extraction efficiency for the detection of analytes. Under the optimal conditions, the proposed analytical method achieved satisfactory linearity (R²  > 0.995), and obtained desirable recoveries ranged from 77.4 to 94.0% with the relative standard deviation of 1.2-6.1% at the concentration levels of 3.2-13.4 µg/kg. The limits of quantitation of atropine, anisodamine, and scopolamine were, respectively, 3.2, 4.6, and 4.5 µg/kg with linearity ranged from 3.2 to 25.4 µg/kg. The modified quick, easy, cheap, effective, rugged, and safe sample preparation with ultra-high-performance liquid chromatography and tandem mass spectrometry method was successfully applied to evaluate the safety of goji berries collected from 30 plant areas in China, suggesting its applicability and suitability for the routine analysis of three tropane alkaloids in goji berries.

Development of a new LC-MS method for accurate and sensitive determination of 33 pyrrolizidine and 21 tropane alkaloids in plant-based food matrices

Setting of maximum limits for a number of plant alkaloids is under discussion in the EU. The novel method developed and optimized in this study enables simultaneous determination of 21 tropane alkaloids (TAs) and 33 pyrrolizidine (PAs) together with their N-oxides (PANOs). For analysis of aqueous-methanolic extract, reversed phase ultra-high-performance liquid chromatography and tandem mass spectrometry (RP-U-HPLC-MS/MS) was employed. The method was validated for frequently contaminated matrices (i) sorghum, (ii) oregano, and (iii) mixed herbal tea. The recoveries at two spiking levels were in the range of 82-115%, 80-106%, and 78-117%, respectively, and repeatabilities were less than 19% for all analyte/matrix combinations. As regards the achieved limits of quantification (LOQ), their values were in the range of 0.5-10 μg kg^-1. The crucial problem encountered during method development, co-elution of multiple groups of isomeric alkaloids, was overcome by subsequent sample separation in the second chromatographic system, hydrophilic interaction liquid chromatography (HILIC), providing different separation selectivity. Lycopsamine, echinatine, and indicine (co-elution group 1) and N-oxides of indicine and intermedine (co-elution group 2), which could not be resolved on the commonly used RP column, were possible to separate fully by using the HILIC system.

Rapid identification and determination of pyrrolizidine alkaloids in herbal and food samples via direct analysis in real-time mass spectrometry

Pyrrolizidine alkaloids (PAs) are naturally occurring plant toxins associated with severe liver damage if excessive ingestion. Herein, a novel analytical strategy on utilizing direct analysis in real-time mass spectrometry (DART-MS) was developed, and applied in analysis of six representative PAs. The calibration curves in the range of 10-1000 ng·mL^-1 were established, and relative standard deviations (RSDs) were less than 10%. The limits of detection (LODs) and limits of quantitation (LOQs) were 0.55-0.85 ng·mL^-1 and 1.83-2.82 ng·mL^-1, respectively. The feasibility of method was indicated by analysing real samples including Gynura japonica, drug tablets, granules, and fresh cow's milk. Moreover, the results of DART-MS were in good agreement with those observed by high performance liquid chromatography mass spectrometry (HPLC-MS), but consumed less time without chromatographic separation. This research provides a facile fashion for safety assessment of herbal and food products containing PAs and presents promising applications in food, pharmaceutical and clinical analysis.

Determination of tropane alkaloids in cereals, tea and herbal infusions: Exploiting proficiency testing data as a basis to derive interlaboratory performance characteristics of an improved LC-MS/MS method

Monitoring of tropane alkaloids is regulated in the European Union in cereal-based foods for infants and young children, tea and herbal infusions. The European Commission's Joint Research Centre (JRC) developed an improved LC-MS/MS analytical method using a pentafluorophenyl column, validated it and conducted two proficiency tests targeting these food categories. A subset of the data gathered from laboratories that used the JRC method was additionally exploited to derive interlaboratory performance characteristics. The method showed fit-for-purpose figures of merit. The LOQs for atropine and scopolamine were around 0.4 and 1.2 µg/kg in cereal products, and in tea and herbal infusions, respectively. Uncertainties varied from 15 to 25%. The reproducibility varied from 11 to 38% for scopolamine and from 17 to 44% for atropine at levels ranging from 0.18 to 18.8 and 1.2-54.0 µg/kg, respectively. Recoveries ranged from 71 to 96%. These performance parameters render the method a good candidate for standardisation.

Interpol review of controlled substances 2016-2019

This review paper covers the forensic-relevant literature in controlled substances from 2016 to 2019 as a part of the 19th Interpol International Forensic Science Managers Symposium. The review papers are also available at the Interpol website at: https://www.interpol.int/content/download/14458/file/Interpol%20Review%20Papers%202019.pdf.

A novel approach for fast and simple determination pyrrolizidine alkaloids in herbs by ultrasound-assisted dispersive solid phase extraction method coupled to liquid chromatography-tandem mass spectrometry

Pyrrolizidine alkaloids (PAs) are secondary plant metabolites witch can contaminate food, especially herbs. Due to the fact that alkaloids have a strong adverse effect on human health, it is necessary to use sensitive and selective detection methods. In present study a modified method based on LC-MS/MS was developed and validated for the simultaneous determination of thirty pyrrolizidine alkaloids and their corresponding N-oxides (PANOs) in herbs samples. Sample extraction was based on ultrasound-assisted dispersive solid phase extraction and clean-up using graphene. Method validation showed that the proposed method hold good recoveries (61-128 %) for PAs/PANOs with RSD <15 %. Limits of quantification has been set at 1 μg kg^-1 level for all targeted alkaloids. The optimized method yielded a small matrix effect (-20-20 %) for most PAs/PANOs. The uncertainty associated with the analytical method was not higher than 38 %. The method is operationally simple, time-saving, and can be applied to the analysis of real herb samples.