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

Comprehensive tropane alkaloids analysis and retrospective screening of contaminants in honey samples using liquid chromatography-high resolution mass spectrometry (Orbitrap)

A wide-scope analytical method was developed and validated for the determination of tropane alkaloids (TAs) in honey samples. A simple and fast extraction procedure, using a mixture of methanol/water/formic acid (75/25/0.4, v/v/v) as extraction solvent, followed by a clean-up with graphitized black carbon (GBC) and magnesium sulphate was optimized, and compounds were analysed by liquid chromatography coupled to high resolution mass spectrometry (LC-HRMS-Orbitrap). Validation of the proposed method provided adequate linearity (R² > 0.99), trueness (recoveries 71-120%) and precision (relative standard deviation, RSD ≤ 20.1%), with limits of quantitation (LOQs) at 20 µg/kg (except anisodamine and scopolamine at 40 µg/kg) and a significant matrix effect (≤-50%). Nineteen honey samples were analysed, but only one was positive, containing 27 µg/kg of scopolamine. Additionally, a post-targeted screening was performed, and 47% of samples were contaminated with different herbicides, insecticides and veterinary drugs. Therefore, the proposed analytical method is a powerful tool for both targeted TAs and post-targeted contaminant analyses.

Straightforward Determination of Pyrrolizidine Alkaloids in Honey through Simplified Methanol Extraction (QuPPE) and LC-MS/MS Modes

Contamination of honey with toxic pyrrolizidine alkaloids (PAs) and their N-oxides (PANOs) was assessed by dilution with acidic methanol and analysis through liquid chromatography (LC) coupled with tandem mass spectrometry (MS/MS) in three different modes. The hybrid linear trap/triple quadrupole (LC-QTRAP) instrument was used in precursor ion scan (PIS), enhanced product ion scan (EPI), and multiple reaction monitoring (MRM) mode. The parent ions from ions at m/z 120 or 138 amus, characteristic of all the toxic PAs and PANOs in the sample were first scanned by PIS. Then, the presence of each contaminant at specific retention times through its MS2 spectrum was confirmed by EPI. Finally, they were quantified in the MRM mode. The method was validated: recoveries 86-111%, relative standard deviation (RSD) <20%, at 20 and 40 μg/kg, except retrorsine, which showed a RSD of 30% at 20 μg/kg. Honey samples were analyzed and five of them showed levels of 40 μg/kg for the sum (PAs + PANOs). This approach allows the simultaneous determination of PAs and PANOs in honey, even if their chemical standards are not available.

Screening 89 Pesticides in Fishery Drugs by Ultrahigh Performance Liquid Chromatography Tandem Quadrupole-Orbitrap Mass Spectrometer

Multiclass screening of drugs with high resolution mass spectrometry is of great interest due to its high time-efficiency and excellent accuracy. A high-scale, fast screening method for pesticides in fishery drugs was established based on ultrahigh performance liquid chromatography tandem quadrupole-Orbitrap high-resolution mass spectrometer. The target compounds - were diluted in methanol and extracted by ultrasonic treatment, and the extracts were diluted with MeOH-water (1:1, v/v) and centrifuged to remove impurities. The chromatographic separation was performed on an Accucore aQ-MS column (100 mm × 2.1 mm, 2.6 μm) with gradient elution using 0.1% formic acid in water (containing 5 mmol/L ammonium formate) and 0.1% formic acid in methanol (containing 5 mmol/L ammonium formate) in Full Scan/dd-MS2 (TopN) scan mode. A screening database, including mass spectrometric and chromatographic information, was established for identification of compounds. The screening detection limits of methods ranged between 1–500 mg/kg, the recoveries of real samples spiked with the concentration of 10 mg/kg and 100 mg/kg standard mixture ranged from 70% to 110% for more than sixty compounds, and the relative standard deviations (RSDs) were less than 20%. The application of this method showed that target pesticides were screened out in 10 samples out of 21 practical samples, in which the banned pesticide chlorpyrifos were detected in 3 out of the 10 samples.

Determination of Selected Pyrrolizidine Alkaloids in Honey by Dispersive Liquid-Liquid Microextraction and Ultrahigh-Performance Liquid Chromatography-Tandem Mass Spectrometry

The contamination of honey with hepatotoxic pyrrolizidine alkaloids (PAs) is an actual concern for food safety. This study reports the first application of dispersive liquid-liquid microextraction (DLLME) in the determination of five relevant PAs, and the relative N-oxide derivatives (PANOs), in honey. The effects of different experimental parameters (pH, ionic strength, type and volume of DLLME solvents) affecting the extraction efficiency were carefully investigated and optimized. PAs were extracted from honey (diluted solution 10% w/v at pH 9.5) by injecting a mixture of chloroform and isopropyl alcohol. A reduction step (zinc powder in acidic aqueous solution) before DLLME was performed to convert PANOs in PAs and to obtain the total PA levels. Both sample preparation protocols (DLLME and Zn-DLLME) showed negligible matrix effects on PA signal intensity in honeys of different botanical origins. The overall recoveries of DLLME and Zn-DLLME ranged from 71 to 102% and from 63 to 103%, respectively, with a good precision (standard deviations in the range from 1 to 12%). The attained method quantification limits stayed between 0.03 and 0.06 μg kg^-1, and the linear response range extended to 25 μg kg^-1. Additionally, the proposed method provides results comparable to those of the SPE protocol in the analysis of real samples. An analysis of retail honeys revealed PA residues in all analyzed samples, with a maximum level of 17.5 μg kg^-1 (total PAs). Globally, the proposed method provides a sensitive and accurate determination of analytes and offers numerous advantages, such as simplicity, low cost, and a high sample throughput, which make it suitable for screening and quality control programs in food chain and occurrence studies.

Simultaneous Determination and Risk Assessment of Pyrrolizidine Alkaloids in Artemisia capillaris Thunb. by UPLC-MS/MS Together with Chemometrics

Pyrrolizidine alkaloids (PAs) are natural toxins found in some genera of the family Asteraceae. However, it has not been reported whether PAs are present in the widely used Asteraceae plant Artemisia capillaris Thunb. (A. capillaris). The purpose of this study was to establish a sensitive and rapid UPLC-MS/MS method together with chemometrics analysis for simultaneous determination and risk assessment of PAs in A. capillaris. The developed UPLC-MS/MS method was validated and was confirmed to display desirable high selectivity, precision and accuracy. Risk assessment was conducted according to the European Medicines Agency (EMA) guideline. Chemometrics analysis was performed with hierarchical clustering analysis and principal component analysis to characterize the differences between PAs of A. capillaris. Finally, PAs were found in 29 out of 30 samples and at least two were detected in each sample, besides, more than half of the samples exceeded the EMA baseline. Nevertheless, the chemometrics results suggested that the PAs contents of A. capillaris from different sources varied significantly. The method was successfully applied to the detection and risk evaluation of PAs-containing A. capillaris for the first time. This study should provide a meaningful reference for the rational and safe use of A. capillaris.

Direct injection high performance liquid chromatography coupled to data independent acquisition mass spectrometry for the screening of antibiotics in honey

The targeted analysis of veterinary drug residues in honey traditionally involves a series of extraction and purification steps prior to quantification with high performance liquid chromatography coupled to high resolution or tandem mass spectrometry. These steps, designed to separate the target analytes from interferences, are generally time-consuming and costly. In addition, traditional cleanup steps are likely to eliminate other compounds whose analysis could prove decisive in current or future assessment of the honey sample. Alternatively, direct injection without complex sample preparation steps has been introduced for the fast analysis of trace compounds in environmental and food matrices. The aim of this study was to develop a rapid method for the targeted analysis of 7 key veterinary drug residues in honey based on direct injection high performance liquid chromatography coupled to quadrupole time-of-flight, while simultaneously recording data-independent MS/MS (e.g. All Ions MS/MS data) for future re-examination of the data for other purposes. The new method allowed for the detection of the target residues at levels approximately 20-100 times lower than current regulatory limits, for a total analysis time of about 45 min. The recoveries (103-119%), the linearity (R ≥ 0.996) and the repeatability (RSD ≤ 7%) were satisfactory. The method was then applied to 35 honey samples from the Canadian market. Residues of tylosin A, tylosin B, sulfamethazine and sulfadimethoxine were detected in 6, 9, 6 and 23% of the samples respectively, at levels below the regulatory limits in Canada. The possibility of adding a hydrolysis step to study sulfonamides in honey was tested, which provided good results for this family of compounds but lead to degradation of some of the other analytes. Finally, the non-targeted identification of several compounds was demonstrated as a proof of concept of future re-examination of All Ions MS/MS data. This paper illustrates the capacity of this novel method to combine targeted and non-targeted screening of chemical residues in honey.

Simultaneous determination of pesticides, mycotoxins, tropane alkaloids, growth regulators, and pyrrolizidine alkaloids in oats and whole wheat grains after online clean-up via two-dimensional liquid chromatography tandem mass spectrometry

In this study, a two-dimensional liquid chromatography tandem mass spectrometry method was developed and validated for the determination of pesticide residues and contaminants in whole wheat grains and oats. The samples were extracted with a mixture of acetonitrile and water and were injected into the two-dimensional LC-MS/MS system without any further clean-up or sample preparation. Samples were analyzed with four different matrix matched calibrations. Matrix effects were evaluated by comparing analyte signals in the respective matrix matched standard with the neat solvent standards. The final method was validated according to the current Eurachem validation guide and SANTE document. The number of successfully validated analytes throughout all three validation levels in oats and wheat, respectively, were as follows: 330 and 316 out of 370 pesticides, 6 and 13 out of 18 pyrrolizidine alkaloids and 7 out of 9 regulated mycotoxins. Moreover, both plant growth regulators mepiquat and chlormequat as well as the tropane alkaloids atropine and scopolamine met the validation criteria. The majority of pesticides showed limits of detection below 1 µg kg^-1, pyrrolizidine alkaloids below 0.7 µg kg^-1, tropane alkaloids below 0.2 µg kg^-1, growth regulators below 0.7 µg kg^-1 and mycotoxins below 8 µg kg^-1 in both matrices.

A modified QuEChERS method coupled with liquid chromatography-tandem mass spectrometry for the simultaneous detection and quantification of scopolamine, L-hyoscyamine, and sparteine residues in animal-derived food products

We developed a modified Quick, Easy, Cheap, Effective, Rugged, and Safe (CEN QuEChERS) extraction method coupled with liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI⁺/MS-MS) to identify and quantify residues of three botanical alkaloids, namely, scopolamine, L-hyoscyamine, and sparteine, in animal-derived foods, including porcine muscle, egg, and milk. A combination of ethylenediaminetetraacetic acid disodium buffer and acetonitrile acidified with 0.5% trifluoroacetic acid was used as an extraction solvent, whereas QuEChERS (CEN, 15662) kits and sorbents were applied for cleanup procedures. The proposed method was validated by determining the limits of quantification (LOQs), with values of 1-5 µg/kg achieved for the target analytes in various matrices. Linearity was estimated from matrix-matched calibration curves constructed using six concentration levels ranging from 1- to 6-fold increases in the LOQs of each analyte, and the correlation coefficients (R² ) were ≥0.9869. Recoveries (at three concentration levels of 1-, 2-, and 3-fold increases in the LOQ) of 73-104% were achieved with relative standard deviations (RSDs) ≤7.7% (intra-day and inter-day precision). Ten types of each matrix procured from large markets were evaluated, and all tested samples showed negative results. The current protocol is simple and versatile and can be used for routine detection of plant alkaloids in animal food products.

Identification of Ligularia Herbs Using the Complete Chloroplast Genome as a Super-Barcode

More than 30 Ligularia Cass. (Asteraceae) species have long been used in folk medicine in China. Morphological features and common DNA regions are both not ideal to identify Ligularia species. As some Ligularia species contain pyrrolizidine alkaloids, which are hazardous to human and animal health and are involved in metabolic toxification in the liver, it is important to find a better way to distinguish these species. Here, we report complete chloroplast (CP) genomes of six Ligularia species, L. intermedia, L. jaluensis, L. mongolica, L. hodgsonii, L. veitchiana, and L. fischeri, obtained through high-throughput Illumina sequencing technology. These CP genomes showed typical circular tetramerous structure and their sizes range from 151,118 to 151,253 bp. The GC content of each CP genome is 37.5%. Every CP genome contains 134 genes, including 87 protein-coding genes, 37 tRNA genes, eight rRNA genes, and two pseudogenes (ycf1 and rps19). From the mVISTA, there were no potential coding or non-coding regions to distinguish these six Ligularia species, but the maximum likelihood tree of the six Ligularia species and other related species showed that the whole CP genome can be used as a super-barcode to identify these six Ligularia species. This study provides invaluable data for species identification, allowing for future studies on phylogenetic evolution and safe medical applications of Ligularia.

Pyrrolizidine Alkaloids: Chemistry, Pharmacology, Toxicology and Food Safety

Pyrrolizidine alkaloids (PA) are widely distributed in plants throughout the world, frequently in species relevant for human consumption. Apart from the toxicity that these molecules can cause in humans and livestock, PA are also known for their wide range of pharmacological properties, which can be exploited in drug discovery programs. In this work we review the current body of knowledge regarding the chemistry, toxicology, pharmacology and food safety of PA.

Pyrrolizidine Alkaloids in Honey: Determination with Liquid Chromatography-mass Spectrometry Method

INTRODUCTION

Pyrrolizidine alkaloids (PAs) are probably the most widespread toxins of natural origin. More than 6,000 plant species produce these toxic compounds. Bees can forage on flowers of plants producing PAs, which leads to contamination of honey with the toxic compounds. To determine the contamination of honey with PAs, a sensitive method based on liquid chromatography coupled with mass spectrometry has been developed.

MATERIAL AND METHODS

PAs were extracted with 0.05 M sulphuric acid and purified with MCX cartridges. A solvent mixture consisting of ethyl acetate, methanol, acetonitrile, ammonia, and triethylamine (8:1:1:0.1:0.1, v/v) was used to wash alkaloids from the cartridges. After evaporation the residues were reconstituted in water and methanol mixture and subjected to LC-MS analysis.

RESULTS

The developed method was validated according to SANTE/11945/2015 requirements. The recovery was from 80.6% to 114.5%. The repeatability ranged from 2.3% to 14.6%, and the reproducibility was from 4.9% to 17.7%.

CONCLUSIONS

A new method for the determination of PAs in honey has been developed and validated. All evaluated parameters were in accordance with the SANTE/11945/2015 guidance document. Out of 50 analysed honey samples, 16 (32%) were positive for the content of at least one PA.

Multiclass screening of >200 pharmaceutical and other residues in aquatic foods by ultrahigh-performance liquid chromatography-quadrupole-Orbitrap mass spectrometry

A quick screening method of more than 200 pharmaceutical and other residues in aquatic foods based on ultrahigh-performance liquid chromatography-quadrupole-Orbitrap mass spectrometry (UHPLC-Q/Orbitrap MS) was established. In this method, after the addition of 200 μL of 1 M EDTA-Na₂, 2 g of each sample homogenate was extracted successively with 10 mL of acetonitrile and 10 mL of ethyl acetate. The extracts were combined, dried under nitrogen flow, and redissolved in 0.1% formic acid in acetonitrile/water (4:6, v/v) for analysis. The prepared samples were analyzed by UHPLC- Q/Orbitrap MS system in Full MS/ddMS² (full-scan data-dependent MS/MS) mode. Compound identification was performed through comparison of the sample data with the database for standard chemicals, including the retention time, precursor ion, product ions, and isotope pattern for all 206 compounds. Five different aquatic food matrices (carp, shrimp, crab, eel, and mussel) spiked with the analytes at 1, 10, and 50 ng/g were evaluated to assess recoveries, precision, matrix effects, stability, and detection limits using the method. UHPLC analyses required 25 min, and 178-200 analytes met identification criteria at 50 ng/g depending on the matrix. Furthermore, practical application of this method for real samples displayed strong screening capability. Graphical abstract A quick screening method of >200 pharmaceutical and other residues in aquatic foods based on ultrahighperformance liquid chromatography-quadrupole-Orbitrap mass spectrometer was established. Fivedifferent aquatic food matrices, including carp, shrimp, crab, eel and mussel, were studied to evaluatescreen limit at 1, 10 and 50 μg·kg-1 level. Results suggest the high reliability, high time-efficiency and goodsimplicity of the method.

Application of QuEChERS for Determining Xenobiotics in Foods of Animal Origin

The use of pesticides and veterinary drugs results in the appearance of residues of xenobiotics in foods. Thus, several methods have been developed for monitoring them; however, most are tedious and expensive. By contrast, the QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) methodology involves a microextraction that yields small samples and has been applied for the analysis of various xenobiotics including pesticides, antibiotics, and mycotoxins. QuEChERS has shown advantages over other techniques including fast sample preparation, reduced needs for reagents and labware, and versatility. This approach allows the simultaneous determination of pesticides with various polarities and volatilities and can be easily modified for the analysis of a wide range of xenobiotics in various matrices including animal products rich in fat. Nevertheless, to attain high recoveries, the extraction, cleanup, and concentration steps have to be optimized according to the target compounds and matrix. Hence, QuEChERS is a promising and environmentally friendly methodology for the high-throughput routine analysis of xenobiotics in animal products. This review focuses on the application of QuEChERS to foods of animal origin and describes recent developments for the optimization of the analysis of veterinary drugs, pesticides, polycyclic aromatic hydrocarbons, and other compounds of concern.