Enhanced spectrofluorimetric determination of aflatoxin M1 in liquid milk after magnetic solid phase extraction

Dispersive Magnetic Solid-Phase Extraction as a Novelty Sample Treatment for the Determination of the Main Aflatoxins in Paprika

Dispersive magnetic solid-phase extraction (DMSPE) technique is proposed as a new sensitive and effective sample treatment method for the determination of aflatoxins in paprika samples. DMSPE was followed by ultrahigh-performance liquid chromatography and high-resolution mass spectrometry detection (UHPLC-HRMS) using a non-targeted acquisition mode for the detection of main aflatoxins (aflatoxin G1, G2, B1 and B2) and derivatives. DMSPE was based on the use of magnetic nanocomposite coated with polypyrrole (PPy) polymer and the main experimental parameters influencing the extraction efficiency in adsorption and desorption steps have been studied and optimized. Analyses were performed using 250 µL magnetic PPy nanocomposite into the sample solution, adsorbing the analytes in 30 min and desorbing them with ethyl acetate (2 mL) in 15 min. The method has been validated, obtaining quantification limits between 3.5 and 4.7 µg kg-1 and recoveries between 89.5-97.7%. The high recovery rate, wide detection range and the use for the first time of the reusable Fe3O4@PPy nanomaterial in suspension for solid food matrices, guarantee the usefulness of the method developed for adequate control of aflatoxins levels in paprika. The proposed methodology was applied for the analysis of 31 samples (conventional and organic) revealing the absence of aflatoxins in the samples.

Solid-phase extraction techniques based on nanomaterials for mycotoxin analysis: An overview for food and agricultural products

Mycotoxin contamination is a globally concerned problem for food and agricultural products since it may directly or indirectly induce severe threats to human health. Sensitive and selective screening is an efficient strategy to prevent or reduce human and animal exposure to mycotoxins. However, enormous challenges exist in the determination of mycotoxins, arising from complex sample matrices, trace-level analytes, and the co-occurrence of diverse mycotoxins. Appropriate sample preparation is essential to isolate, purify, and enrich mycotoxins from complicated matrices, thus decreasing sample matrix effects and lowering detection limits. With the cross-disciplinary development, new solid-phase extraction strategies have been exploited and integrated with nanotechnology to meet the challenges of mycotoxin analysis. This review summarizes the advance and progress of solid-phase extraction techniques as the methodological solutions for mycotoxin analysis. Emphases are paid on nanomaterials fabricated as trapping media of SPE techniques, including carbonaceous nanoparticles, metal/metal oxide-based nanoparticles, and nanoporous materials. Advantages and limitations are discussed, along with the potential prospects. This article is protected by copyright. All rights reserved.

A Review: Sample Preparation and Chromatographic Technologies for Detection of Aflatoxins in Foods

As a class of mycotoxins with regulatory and public health significance, aflatoxins (e.g., aflatoxin B1, B2, G1 and G2) have attracted unparalleled attention from government, academia and industry due to their chronic and acute toxicity. Aflatoxins are secondary metabolites of various Aspergillus species, which are ubiquitous in the environment and can grow on a variety of crops whereby accumulation is impacted by climate influences. Consumption of foods and feeds contaminated by aflatoxins are hazardous to human and animal health, hence the detection and quantification of aflatoxins in foods and feeds is a priority from the viewpoint of food safety. Since the first purification and identification of aflatoxins from feeds in the 1960s, there have been continuous efforts to develop sensitive and rapid methods for the determination of aflatoxins. This review aims to provide a comprehensive overview on advances in aflatoxins analysis and highlights the importance of sample pretreatments, homogenization and various cleanup strategies used in the determination of aflatoxins. The use of liquid-liquid extraction (LLE), supercritical fluid extraction (SFE), solid phase extraction (SPE) and immunoaffinity column clean-up (IAC) and dilute and shoot for enhancing extraction efficiency and clean-up are discussed. Furthermore, the analytical techniques such as gas chromatography (GC), liquid chromatography (LC), mass spectrometry (MS), capillary electrophoresis (CE) and thin-layer chromatography (TLC) are compared in terms of identification, quantitation and throughput. Lastly, with the emergence of new techniques, the review culminates with prospects of promising technologies for aflatoxin analysis in the foreseeable future.

Detection Methods for Aflatoxin M1 in Dairy Products

Mycotoxins are toxic compounds produced mainly by fungi of the genera Aspergillus, Fusarium and Penicillium. In the food chain, the original mycotoxin may be transformed in other toxic compounds, reaching the consumer. A good example is the occurrence of aflatoxin M1 (AFM1) in dairy products, which is due to the presence of aflatoxin B1 (AFB1) in the animal feed. Thus, milk-based foods, such as cheese and yogurts, may be contaminated with this toxin, which, although less toxic than AFB1, also exhibits hepatotoxic and carcinogenic effects and is relatively stable during pasteurization, storage and processing. For this reason, the establishment of allowed maximum limits in dairy products and the development of methodologies for its detection and quantification are of extreme importance. There are several methods for the detection of AFM1 in dairy products. Usually, the analytical procedures go through the following stages: sampling, extraction, clean-up, determination and quantification. For the extraction stage, the use of organic solvents (as acetonitrile and methanol) is still the most common, but recent advances include the use of the Quick, Easy, Cheap, Effective, Rugged, and Safe method (QuEChERS) and proteolytic enzymes, which have been demonstrated to be good alternatives. For the clean-up stage, the high selectivity of immunoaffinity columns is still a good option, but alternative and cheaper techniques are becoming more competitive. Regarding quantification of the toxin, screening strategies include the use of the enzyme-linked immunosorbent assay (ELISA) to select presumptive positive samples from a wider range of samples, and more reliable methods-high performance liquid chromatography with fluorescence detection or mass spectroscopy-for the separation, identification and quantification of the toxin.

A miniaturized solid-phase extraction adsorbent of calix[4]arene-functionalized graphene oxide/polydopamine-coated cellulose acetate for the analysis of aflatoxins in corn

A calix[4]arene-functionalized graphene oxide/polydopamine-coated cellulose acetate adsorbent was fabricated for the pre-concentration of aflatoxins. The highly porous developed adsorbent does not produce the high backpressure that normally occurs in particle-packed cartridges and its large surface area helps to improve adsorption. The highly efficient adsorption of aflatoxins by the hybrid adsorbent is facilitated via hydrogen bonding and hydrophobic and π-π interactions. Polymerization time, amount of calix[4]arene-functionalized graphene oxide, type and volume of desorption solvent, sample pH, sample volume, and sample flow rate were optimized. The linearity of aflatoxin B1 was in the range of 0.01-10.0 μg/kg, aflatoxin B2 was in the range of 0.02-10.0 μg/kg and aflatoxin G1 and aflatoxin G2 were in the range of 0.050-10.0 μg/kg. The limits of detection were 0.01 μg/kg for aflatoxin B1, 0.02 μg/kg for aflatoxin B2 and 0.05 μg/kg for aflatoxin G1 and aflatoxin G2. The developed calix[4]arene-functionalized graphene oxide/polydopamine-coated cellulose acetate adsorbent was successfully utilized for the analysis of aflatoxins from corn samples and the extraction efficiency was satisfactory with obtained recoveries from 83.0 to 106.7%. Moreover, fabricated adsorbent is easy to prepare, inexpensive, and can be reused.

Magnetic Solid Phase Extraction Applied to Food Analysis

Magnetic solid phase extraction has been used as pretreatment technique for the analysis of several compounds because of its advantages when it is compared with classic methods. This methodology is based on the use of magnetic solids as adsorbents for preconcentration of different analytes from complex matrices. Magnetic solid phase extraction minimizes the use of additional steps such as precipitation, centrifugation, and filtration which decreases the manipulation of the sample. In this review, we describe the main procedures used for synthesis, characterization, and application of this pretreatment technique which were applied in food analysis.

Developments in mycotoxin analysis: an update for 2013-2014

This review highlights developments in the determination of mycotoxins over a period between mid-2013 and mid-2014. It continues in the format of the previous articles of this series, emphasising on analytical methods to determine aflatoxins, Alternaria toxins, ergot alkaloids, fumonisins, ochratoxins, patulin, trichothecenes and zearalenone. The importance of proper sampling and sample preparation is briefly addressed in a dedicated section, while another chapter summarises new methods used to analyse botanicals and spices. As LC-MS/MS instruments are becoming more and more widespread in the determination of multiple classes of mycotoxins, another section is focusing on such newly developed multi-mycotoxin methods. While the wealth of published methods during the 12 month time span makes it impossible to cover every single one, this exhaustive review nevertheless aims to address and briefly discuss the most important developments and trends.

Spectrofluorimetric determination of zearalenone using dispersive liquid–liquid microextraction coupled to micro-solid phase extraction onto magnetic nanoparticles

A new and sensitive method using dispersive liquid–liquid microextraction (DLLME) coupled to micro-solid phase extraction (μ-SPE) onto magnetic nanoparticles was developed for spectrofluorimetric determination of zearalenone (ZEN) in corn samples.