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Alternaria
Published in Dongyou Liu, Laboratory Models for Foodborne Infections, 2017
Alicia Rodríguez, Andrea Patriarca, Mar Rodríguez, María Jesús Andrade, Juan José Córdoba
Mycotoxin determination has been traditionally carried out by thin-layer chromatography (TLC), gas chromatography (GC), and mainly high-performance liquid chromatography (HPLC), usually with ultraviolet (UV) detection, although fluorescence and electrochemical detection have also been used for certain toxins. Atmospheric pressure chemical ionization (APCI), LC-mass spectroscopy (MS), and LC-MS/MS have been applied to the determination and confirmation of AOH and AME identity at sub ng/mL levels.33,38 Several multimycotoxin methods have been recently developed, many of which include the detection of Alternaria toxins, most of them based on LC-MS/MS systems. A multimethod for detection of 33 mycotoxins (including AOH and AME) in various food matrices has been developed by Spanjer et al.,39 based on LC-MS/MS using an electrospray ionization interface (ESI) for detection and MS/MS with multiple reaction monitoring (MRM). Rasmussen et al.40 developed a method for simultaneous detection of 27 mycotoxins (including AOH, AME, TeA, and altersetin) in maize silage. A simple pH-buffered sample extraction has been developed based on the QuEChERS method, and the detection is made by LC-MS/MS without further cleanup. Wang et al.41 developed an LC-MS/MS method for detecting 17 mycotoxins (including AOH and AME) with application in traditional Chinese medicine products, using a MultiPurification Column for cleanup.
Aflatoxins
Published in Dongyou Liu, Handbook of Foodborne Diseases, 2018
María J. Andrade, Elena Bermúdez, Alicia Rodríguez, Mar Rodríguez, Juan J. Córdoba
For analysis of aflatoxin synthesis by the foodborne Aspergillus strains, accurate and sensitive analytical methods for their detection are continuing to be developed due to their carcinogenicity. The evaluation of aflatoxin production comprises sample pretreatment methods (toxin extraction and clean-up procedures) and the qualitative or quantitative analysis of the mycotoxins.94–96 Clean-up procedures are normally necessary when a complex matrix is involved95; however, the QuEChERS-based approaches are widely used for extraction of aflatoxins from foods.97 This extraction technique includes soaking the sample prior to extraction, which allows a better extraction with the organic solvent,98 and acidification of the solvents that facilitates the isolation of these mycotoxins.97,99 After pretreatment methods, aflatoxins should be separated from coextracted impurities that could interfere in their analysis. Aflatoxins are low mass polar compounds that contain natural UV absorption and fluorescence properties. These characteristics make easy their separation from food constituents and other compounds using liquid separation chromatographic techniques instead of other chromatographic-based techniques.94,96 Specifically, the natural or induced fluorescence, after the derivatization process,100 of these compounds has traditionally allowed their detection by thin-layer chromatography relying on evaluating fluorescent spots observed under a long wavelength UV light.94 In fact, the designation of aflatoxins types “B” and “G” relied on their respective blue and green fluorescence colors. This low-cost and rapid analytical technique allows the screening of high amounts of samples yielding qualitative or semiquantitative results by visual inspection.95 Currently, the use of high-performance liquid chromatography (HPLC) coupled to a fluorescence detector is being used as the method of choice in official analysis.94,96,101,102 It has been widely used to detect and quantify aflatoxins in figs, maize, and other foodstuffs.101–104 Although quantification of aflatoxins by HPLC is mainly conducted by fluorescence detection, new methods coupled to mass spectrometry (MS) detector are published.96,105 The coupling of HPLC to MS via atmospheric pressure ionization techniques, such as electrospray ionization or atmospheric pressure chemical ionization, has favored the advent of new methods for single mycotoxin or single mycotoxin groups (such as aflatoxins).105 The advantage of LC-MS or LC-MS/MS consists in the detection limits, the confirmation provided by online mass spectral fragmentation patterns, and the ability to filter out by mass any impurities in spectrophotometric detectors.94–96 Although gas chromatography is not a common technique used for aflatoxin separation, this technique coupled to a MS detector has been used for aflatoxin analysis by some authors.106,107 Another interesting technique for separating aflatoxins from foods and other coextracted impurities can be capillary electrophoresis, particularly micellar electrokinetic capillary chromatography with laser-induced fluorescence detection.96
Analyzing pesticides and metal(loid)s in imported tobacco to Saudi Arabia and risk assessment of inhalation exposure to certain metals
Published in Inhalation Toxicology, 2022
Mohammed A. Al Mutairi, Hatim A. Al Herbish, Rakan S. Al-Ajmi, Hatim Z. Alhazmi, Reham A. Al-Dhelaan, Abdullah M. Alowaifeer
Extraction was carried out using the QuEChERS method. Briefly, 2 g of crushed tobacco was weighed and placed in a 50 ml polypropylene tube, then 10 ml of cold distilled water was added, and the tube was mixed uniformly for 1 min. The tube was left to stand to moisten pulverized tobacco powder. After 10 min, acetonitrile was added, and the tube was vortexed for 1 min, then placed into a −18 °C refrigerator for 10 min. Afterward, 4 g of MgSO4 salt was added, and the tube was shaken for 2 min and centrifuged at 4000 rpm for 5 min. Then, 6 ml of the supernatant was transferred to a dispersive SPE tube (855 mg MgSO4/150 mg CUPSA/45 mg CUCARB), and the tube was vortexed for 2 min. The SPE tube was centrifuged at 4000 rpm for 5 min, and the filtrate was collected and filtered through a 0.20 um filter. Samples were transferred into a 2 ml vial for the analysis on the GC and LC.
Simultaneous analysis of mycotoxins in corn flour using LC/MS-MS combined with a modified QuEChERS procedure
Published in Toxin Reviews, 2018
Maryam Amirahmadi, Shahram Shoeibi, Hossein Rastegar, Mehdi Elmi, Amin Mousavi Khaneghah
In the present study, the modified QuEChERS procedure was used for sample preparation. To choose a suitable extraction solvent, different mixtures of water/organic compositions (ACN and MeOH) at various ratios were examined. By using the methanol/water as solvent especially in the case of aflatoxin B1, some unfavorable peak shapes were observed, while the most suitable results were acquired by using ACN as the organic solvent. After evaluation of several ratios, the optimum result corresponded to H2O/ACN (20:80), which offered satisfactory recoveries for all target mycotoxins except OTA. This poor accuracy and precision of OTA recovery could be attributed to the ionic affinity of the primary and/or secondary amines and support carboxyl groups between OTA and PSA, which results in absorption of OTA by PSA (Tamuura et al.2011).
Monitoring of pesticides residues in soil samples from the southern districts of Jordan in 2016/2017
Published in Toxin Reviews, 2021
Mohammed H. Kailani, Tawfiq M. Al-Antary, Mahmoud A. Alawi
There is no modification from the QuEChERS method which is mentioned above. Therefore, detection limits, trueness, and precision studies were performed for verification of extraction method and LC-MS/MS instruments performance. The detection limit, which was derived from the analysis of 10 independent sample blanks fortified at lowest concentration that gave acceptable recoveries (between 70% and 120%) and precision (RSD < 20%), were determined for each sample (European Commission DG-SANTE 2017). For recovery and precision studies, three different concentrations were used at 0.01, 0.1, and 0.5 mg/kg. Pesticide-free sand samples were spiked six times at these concentrations. The results were used to determine the recovery and relative standard deviation (RSD).