Determination of multiple mycotoxin residues in Panax ginseng using simultaneous UPLC-ESI-MS/MS

Determination of nine bioactive phenolic components usually found in apple juice by simultaneous UPLC-MS/MS

The functional food ingredients of apple juice can significantly change during processing, transportation, and storage, thus affecting the quality of the product. A simple and derivation-free analytical method based on ultra-high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was developed and optimized for the simultaneous determination of functional food ingredients in apple juice bought in the market. Cleanup steps and chromatographic conditions were optimized to remove interference and decrease the matrix effect. The nine target analytes were separated on an Acquity UPLC system equipped with a BEH C18 column and detected by electrospray ionization source (ESI) operating in positive subsection acquisition mode under multiple reaction monitoring (MRM) conditions. The results showed that p-hydroxybenzoic acid, protocatechuate, caffeic acid, chlorogenic acid, epicatechin, phloridzin, hyperoside, procyanidin B₂, and rutin could be sufficiently separated for content determination within 6 min. In the concentration range of 20 μg/L-50 mg/L, nine standard samples exhibited a good linear fit with correlation coefficients above .985.

Current Developments of Analytical Methodologies for Aflatoxins' Determination in Food during the Last Decade (2013-2022), with a Particular Focus on Nuts and Nut Products

This review aims to provide a clear overview of the most important analytical development in aflatoxins analysis during the last decade (2013-2022) with a particular focus on nuts and nuts-related products. Aflatoxins (AFs), a group of mycotoxins produced mainly by certain strains of the genus Aspergillus fungi, are known to impose a serious threat to human health. Indeed, AFs are considered carcinogenic to humans, group 1, by the International Agency for Research on Cancer (IARC). Since these toxins can be found in different food commodities, food control organizations worldwide impose maximum levels of AFs for commodities affected by this threat. Thus, they represent a cumbersome issue in terms of quality control, analytical result reliability, and economical losses. It is, therefore, mandatory for food industries to perform analysis on potentially contaminated commodities before the trade. A full perspective of the whole analytical workflow, considering each crucial step during AFs investigation, namely sampling, sample preparation, separation, and detection, will be presented to the reader, focusing on the main challenges related to the topic. A discussion will be primarily held regarding sample preparation methodologies such as partitioning, solid phase extraction (SPE), and immunoaffinity (IA) related methods. This will be followed by an overview of the leading analytical techniques for the detection of aflatoxins, in particular liquid chromatography (LC) coupled to a fluorescence detector (FLD) and/or mass spectrometry (MS). Moreover, the focus on the analytical procedure will not be specific only to traditional methodologies, such as LC, but also to new direct approaches based on imaging and the ability to detect AFs, reducing the need for sample preparation and separative techniques.

A facile "turn-on" fluorescent aptasensor for simultaneous detection of dual mycotoxins in traditional Chinese medicine based on graphene oxide and FRET

Mycotoxin is a common sort of harmful contaminant in traditional Chinese medicine (TCM), which is in a great demand of controlling. On this account, a facile "turn-on" fluorescent aptasensor based on fluorescence resonance energy transfer (FRET) for simultaneous detection of patulin (PAT) and zearalenone (ZEN) was developed. In this study, the aptamers of PAT and ZEN were labeled by FAM and Cy3, respectively, serving as fluorescence probes. Both aptamers could adsorb on the surface of graphene oxide (GO) via π-π stacking, which will consequently result in the occurrence of FRET between the fluorophores and GO. In the absence of the targets, the fluorescence would be quenched "off". In the presence of any of the dual mycotoxins, the corresponding aptamers would interact with the targets and release from GO due to the conformational variation, leading to a fluorescence "turn-on" effect. The limit of detection of this difunctional aptasensor was 2.29 nM for PAT and 0.037 nM for ZEN, respectively. This aptasensing platform exhibited satisfactory selectivity against interferents and reliability in real TCM sample detection. To our knowledge, it is the first aptasensor based on GO and FRET that realizes simultaneous detection of dual mycotoxin in TCM. Moreover, the measurement takes merely ∼60 min, does not need complicated pretreatment, and uses only inexpensive aptamer and GO as consuming materials. To sum up, this aptasensor exhibits great potential in fast, cost-effective and reliable simultaneous detection of multiple targets, and is expected to contribute to the quality and safety control of TCM.

Establishment of a Chemiluminescence Immunoassay Combined with Immunomagnetic Beads for Rapid Analysis Of Ochratoxin A

BACKGROUND

Ochratoxins A (OTA), as the harmful mycotoxins, are toxic secondary metabolite produced by several species of Aspergillus and Penicillium. Hence, it is of vital important to establish a sensitive method to detect OTA in various grains.

OBJECTIVE

Herein a novel highly sensitive chemiluminescence immunoassay was developed to determination of ochratoxin A in wheat, corn, and poultry feed.

METHODS

The immunomagnetic beads were used as solid phase carrier and separator in the competitive chemiluminescence method, the monoclonal antibodies anti-OTA coated on immunomagnetic beads were applied as the capturing antibody, in which OTA would compete with Ochratoxin A-alkaline phosphatase (OTA-ALP) in binding with OTA antibodies.

RESULTS

The proposed method exhibited good linearity (R2 ≥ 0.999), adequate OTA recovery rate (83.60% to 102.50%), and good repeatability. The sensitivity of the proposed method was 2.05 pg/mL. In addition, the method was highly selective, it did not have cross-reaction with other mycotoxin (e.g., AFB1, DON, ZEN). Furthermore, the developed method was applied in the analysis of wheat, corn and two animal feeds successfully, the results obtained by the chemiluminescence method showed the high correlation with those obtained by HPLC method (correlation coefficient 0.9958) when testing each extract by both methods.

CONCLUSIONS

This strategy shows great potential application for other toxic and harmful mycotoxin detection.

HIGHLIGHTS

A novel highly rapid and sensitive chemiluminescence immunoassay was established to quantitation for ochratoxin A.

Reduced graphene oxide-zinc oxide nanocomposite as dispersive solid-phase extraction sorbent for simultaneous enrichment and purification of multiple mycotoxins in Coptidis rhizoma (Huanglian) and analysis by liquid chromatography tandem mass spectrometry

In the current study, a robust dispersive solid-phase extraction (dSPE) strategy using reduced graphene oxide-zinc oxide (rGO-ZnO) nanocomposite as the sorbent was proposed for separation, purification and enrichment of 12 mycotoxins in Coptidis rhizoma (Huanglian). The targeted mycotoxins included aflatoxin B1, aflatoxin B2, aflatoxin G1, aflatoxin G2, aflatoxin M1, alternariol-methylether, mycophenolic acid, ochratoxin A, penitrem A, nivalenol, zearalenone and zearalanone. The rGO-ZnO nanocomposite was successfully synthesized through hydrothermal process by a modified Hummers method, and further characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), FTIR spectroscopy, ultraviolet-visible spectroscopy and X-ray diffraction (XRD). Several key parameters affecting the performance of the dSPE approach were extensively investigated, and after optimization, acetonitrile/water/formic acid (80/19/1, v/v/v) as the extraction solution, 2% acetonitrile as the adsorption solution, 15 mg rGO-ZnO as the sorbent, n-hexane as the washing solution, and methanol/formic acid (99/1, v/v) as the desorption solution presented an excellent purification and enrichment efficiency. Under the optimal dSPE procedure followed by analysis with ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS), adequate linearity (R2 ≥ 0.991), high sensitivity (limit of quantification in the range of 0.09-0.41 µg kg-1), acceptable recovery (70.3-105.7%) and satisfactory precision (RSD 1.4-15.0%) were obtained. The analysis of 12 selected mycotoxins was also carried out in real Coptidis rhizoma (Huanglian) samples for applicability evaluation of the established method.

Mycotoxin Contamination Concerns of Herbs and Medicinal Plants

Plants and medicinal herbs that are available on the market do not always meet quality and safety standards. One particular concern is the risk of contamination with mycotoxins. Aflatoxins and ochratoxin A are the most frequently described mycotoxins in herbal products and have repeatedly been reported to occur at concentrations which exceed regulatory levels set by the European Union (EU). Possible solutions include enforcing existing limits, and for the new materials, establishing tighter limits and mandate the growth of medicinal plants in EU member countries under more strict conditions.

Nanobody-alkaline phosphatase fusion-mediated phosphate-triggered fluorescence immunoassay for ochratoxin a detection

Ochratoxin A (OTA) is a kind of mycotoxin that seriously harms the health of humans and animals. In this study, a nanobody-alkaline phosphatase fusion-mediated phosphate-triggered fluorescence immunoassay (Nb-AP-mediated PT-FIA) was developed for detecting OTA. Based on the constructed phosphate-triggered fluorescence sensing system for Nb-AP and the optimal working conditions, the Nb-AP-mediated PT-FIA has a half maximal inhibition concentration (IC₅₀) of 0.46 ng/mL, a limit of detection (IC₁₀) of 0.12 ng/mL, and a linear range (IC_20-80) of 0.2-1.26 ng/mL, respectively. The recovery experiment indicated acceptable accuracy and precision of the Nb-AP-mediated PT-FIA, and the results were validated by high performance liquid chromatography with fluorescence detector. Thus this proposed method is applicable to sensitive, rapid, and low-cost detection of OTA and other toxic analytes with low molecular weight in food and environment.

Quantification and confirmation of four aflatoxins using a LC-MS/MS QTRAP system in multiple reaction monitoring, enhanced product ion scan, and MS3 modes

A simple, rapid, and efficient liquid chromatography tandem mass spectrometry (LC-MS/MS) method, operated in electrospray ionization and quadrupole linear ion trap modes, has been developed for the identification and structural characterization of aflatoxins in peanuts and its derivative products or bean sauce. Samples (5 g) were extracted with acetonitrile/water/formic acid (79:20:1, v/v). After centrifugation and dilution, the extracts were separated on a C18 analytical column by gradient elution (acetonitrile/0.2% formic acid) and analyzed by UPLC-MS/MS. External calibration was used for qualification. The developed multiple reaction monitoring-information-dependent acquisition-enhanced product ion method enabled quantification and confirmation of the analytes in a single run. Enhanced product ion mode was used for qualitative analysis, while multiple reaction monitoring mode was used for quantitative analysis. An in-house library was constructed for identification. Calibration curves showed good linearity with correlation coefficients (r) higher than 0.994. Limits of detection were determined to be below 0.26 µg kg^-1 for most analytes. The recoveries for those substances were in the acceptable range of 80.2%-119.1%. A new LC-MS³ method was established for further confirmation. One pickled pepper peanut was found to contain aflatoxins B1, B2, and G1 with contents of 90.93, 26.64, and 1.92 µg kg^-1, respectively.

Fluorometric lateral flow immunoassay for simultaneous determination of three mycotoxins (aflatoxin B1, zearalenone and deoxynivalenol) using quantum dot microbeads

A fluorometric lateral flow immunoassay (LFA) is described for the simultaneous determination of the mycotoxins aflatoxin B₁ (AFB₁), zearalenone (ZEN) and deoxynivalenol (DON). The method is based on the use of CdSe/SiO₂ quantum dot microbeads (QBs) with a mean diameter of 106 nm. These have strong red luminescence (with excitation/emission peaks at 365/622 nm) which results in enhanced sensitivity. The QBs binding with monoclonal antibodies (mAbs) as the signal probes can react specifically with AFB₁, ZEN and DON, respectively. There is an inverse correlation between the fluorescence signal intensity of test line and the analyte content, which can realize the quantitative analysis of analytes within 15 min. The limits of detection in solution are 10, 80 and 500 pg mL^-1 for AFB₁, ZEN and DON, respectively. Besides, the average recoveries from spiked feed range from 85.5 to 119.0%, and the relative standard deviations are less than 16.4% for both intra- and inter-day assays. The method was used to analyze naturally contaminated feedstuff, and this resulted in a good agreement with data obtained by LC-MS/MS. Graphical abstractSchematic representation of a fluorometric method for the simultaneous determination of three mycotoxins. Quantum dot microbeads (QBs) binding with monoclonal antibodies (mAbs) are signal probes. There is an inverse correlation between the fluorescence intensity of test line and the analyte concentration.

Development of an economic ultrafast liquid chromatography with tandem mass spectrometry method for trace analysis of multiclass mycotoxins in Polygonum multiflorum

Rapid, economic, and highly effective determination of multiple mycotoxins in complex matrices has given huge challenges for the analytical method. In this study, an economic analytical strategy based on sensitive and rapid ultrafast liquid chromatography coupled to hybrid triple quadrupole/linear ion trap mass spectrometry technique was developed for the determination of seven mycotoxins of different chemical classes (aflatoxin B₁ , B₂ , G₁ , and G₂ , ochratoxin A, T-2 toxin, and HT-2 toxin) in Polygonum multiflorum. Target mycotoxins were completely extracted using a modified quick, easy, cheap effective, rugged, and safe method without additional clean-up steps. The types of extraction solvents and adsorbents for the extraction procedure were optimized to achieve high recoveries and reduce coextractives in the final extracts. Due to significant matrix effects for all analytes (≤68.9% and ≥110.0%), matrix-matched calibration curves were introduced for reliable quantification, exploring excellent linearity for the seven mycotoxins with coefficients of determination >0.9992. The method allowed high sensitivity with limit of detection in the range of 0.031-2.5 μg/kg and limit of quantitation in the range of 0.078-6.25 μg/kg, as well as satisfactory precision with relative standard deviations lower than 8%. Recovery rates were between 74.3 and 119.8% with relative standard deviations below 7.43%. The proposed method was successfully applied for 24 batches of P. multiflorum samples, and six samples were found to be positive with aflatoxin B₁ , B₂ , G₁ , or ochratoxin A. The method with significant advantages, including minimum analytical time, low time and solvent consumption, and high sensitivity, would be a preferred candidate for economic analysis of multiclass mycotoxins in complex matrices.