Automated hollow-fiber liquid-phase microextraction coupled with liquid chromatography/tandem mass spectrometry for the analysis of aflatoxin M₁ in milk

HPLC-FLD determination of aflatoxins M1 and M2 in raw cow milk samples using in-syringe gas-controlled density tunable solidification of a floating organic droplet-based dispersive liquid-liquid microextraction method

Herein, an in-syringe gas-controlled density tunable solidification of a floating organic droplet-based dispersive liquid-liquid microextraction method was employed for the extraction of aflatoxin M1 and M2 from cow milk samples prior to their quantification with high-performance liquid chromatography equipped with a fluorescence detector. In this method, after precipitating the proteins of the sample using a zinc sulfate solution, the supernatant phase was transferred into a barrel of a glass syringe, with the end closed with a septum containing a mixture of menthol, phenylacetic acid DES (as the extraction solvent), and chloroform (as a density modifier). After that, an inert gas was bubbled into the syringe. In this manner, chloroform was evaporated and fine droplets of extractant were released, which extracted the analytes during their passing. Finally, the syringe was placed in an ice bath and the obtained solidified drop was injected into the separation system after diluting with a mobile phase. Under the best analysis conditions, low limits of detection (1.45 and 1.86 ng L-1 for AFM1 and AFM2, respectively) and quantification (4.83 and 6.21 ng L-1 for AFM1 and AFM2, respectively), high extraction recovery (75 and 70% for AFM1 and AFM2, respectively), and good precision (relative standard deviations ≤ 4.8%) were obtained by employing the approach reported in this study. In the end, this method was successfully employed to determine AFM1 and AFM2 in raw cow milk samples collected from Tabriz, Iran.

Solid supports and supported liquid membranes for different liquid phase microextraction and electromembrane extraction configurations. A review

Liquid phase microextraction (LPME) and electromembrane microextraction (EME) can be considered as two of the most popular techniques in sample treatment today. Both techniques can be configurated as membrane-assisted techniques to carry out the extraction. These supports provide the required geometry and stability on the contact surface between two phases (donor and acceptor) and improve the reproducibility of sample treatment techniques. These solid support pore space, once is filled with organic solvents, act as a selective barrier acting as a supported liquid membrane (SLM). The SLM nature is a fundamental parameter, and its selection is critical to carry out successful extractions. There are numerous SLMs that have been successfully employed in a wide variety of application fields. The latter is due to the specificity of the selected organic solvents, which allows the extraction of compounds of a very different nature. In the last decade, solid supports and SLM have evolved towards "green" and environmentally friendly materials and solvents. In this review, solid supports implemented in LPME and EME will be discussed and summarized, as well as their applications. Moreover, the advances and modifications of the solid supports and the SLMs to improve the extraction efficiencies, recoveries and enrichment factors are discussed. Hollow fiber and flat membranes, including microfluidic systems, will be considered depending on the technique, configuration, or device used.

Determination of aflatoxin B1 by novel nanofiber-packed solid-phase extraction coupled with a high performance liquid chromatography-fluorescence detector

A novel analytical proposal based on nanofiber-packed solid-phase extraction coupled with high performance liquid chromatography-fluorescence detector (HPLC-FLD) has been successfully developed for determining aflatoxin B1 (AFB1) in foods. Four types of nanofibers, including polystyrene (PS) nanofibers, polypyrrole (PPY) nanofibers, polystyrene-acrylic resin (PS-AR) nanofibers, and polystyrene-polyvinyl pyrrolidone (PS-PVP) nanofibers, were fabricated by electrospinning and utilized to prepare a home-made extraction device. In this study, the factors of different fibers, namely, fiber dosage, pH of extraction solution, type of salt ion, concentration of salt ion, and volume of the eluent were optimized. Under optimized conditions, the method showed good linearity in the range of 0.1-40 ng mL^-1 with a correlation coefficient greater than 0.999 and good inter-day accuracy (90.8-112.7% recovery) and precision (1.8-3.6% intra-day RSDs, 2.6% inter-day RSD), and the limit of detection (LOD) was 0.05 ng mL^-1. Due to its cost-effective, time-saving, environmentally friendly, and simple performance, it has the potential to be utilized to determine aflatoxins in complicated matrices.

Herbal medicine for the treatment of chronic rhinosinusitis: A systematic review and meta-analysis

Objectives: Chronic rhinosinusitis (CRS) is a disease with a high prevalence and a high socioeconomic burden. This study aimed to conduct a comprehensive systematic review to update the evidence on the use of herbal medicine (HM) for CRS treatment.

Methods: A total of 14 electronic databases for randomized controlled trials (RCTs) evaluating the effects of HM on the treatment of CRS were searched for articles published before July 2021. The primary outcome was CRS severity post-treatment, measured with the Visual Analogue Scale (VAS) and Total Effective Rate (TER). The risk of bias of the included studies and the quality of evidence of the main findings were assessed using the Cochrane Collaboration’s risk of bias tool and the Grading of Recommendations, Assessment, Development, and Evaluations tool.

Results: A total of 80 RCTs were included. Compared to placebo, HM significantly improved CRS severity as measured by TER and VAS. When HM was compared with conventional treatment (CT) as monotherapy or adjuvant therapy, CRS severity measured by TER and VAS, quality of life, Lund-Kennedy endoscopy score, Lund-Mackay computed tomography score, and nasal mucociliary function were significantly improved in the HM group. No serious adverse events associated with HM were reported. The risk of bias was generally unclear, and the quality of evidence ranged from moderate to low.

Conclusion: This review found some limited clinical evidence that HM or HM combined with CT may be more effective and safer than CT alone in treating CRS. However, the methodological quality of the included studies was generally low, and the quality of the evidence needs to be improved.

Combination of solvent extraction with deep eutectic solvent based dispersive liquid-liquid microextraction for the analysis of aflatoxin M1 in cheese samples using response surface methodology optimization

A new extraction procedure based on combination of a solvent extraction and deep eutectic solvent based dispersive liquid-liquid microextraction has been introduced for the extraction of aflatoxin M₁ from cheese samples. In this method, acetonitrile, deionized water, and n-hexane are added onto the sample and vortexed. Owning to different affinities of the substances in cheese toward the mentioned solvents, an efficient and selective extraction of the analyte is done in the acetonitrile phase. After centrifugation, the acetonitrile phase is removed and mixed with a new hydrophobic deep eutectic solvent prepared from N,N-diethanol ammonium chloride and carvacrol as an extraction solvent. The mixture is injected into deionized water, and a cloudy solution is obtained. Eventually, an aliquot of the organic phase is injected into high-performance liquid chromatography-fluorescence detection. After optimizing the effective parameters with the response surface methodology and a quadratic model, limits of detection and quantification were 0.74 and 2.56 ng/kg, respectively. The obtained extraction recovery and enrichment factor were 94% and 94, respectively. Also, intra- (n = 6) and interday (n = 4) precisions were less than or equal to 8.6% at a concentration of 5 ng/kg. The suggested method was applied to determine aflatoxin M₁ in different cheese samples.

Evaluation of Two Fully Automated Setups for Mycotoxin Analysis Based on Online Extraction-Liquid Chromatography-Tandem Mass Spectrometry

Mycotoxins are secondary metabolites of fungi species widely known for their potentially toxic effects on human health. Considering their frequent presence in crops and their processed food, monitoring them on food-based matrices is now an important topic. Within such a context, the sample preparation step is usually mandatory before the chromatographic analysis, due to the complexity of matrices such as nuts, cereals, beverages, and others. For these reasons, we herein present the evaluation of two greener setups, based on the automation and miniaturization of the sample preparation step for mycotoxin analysis in different beverages. Firstly, we describe an analytical method based on a multidimensional assembly, coupling a lab-made microextraction column (508 µm i.d. × 100 mm) to a UPLC–MS/MS for the analysis of ochratoxin A in beverages. This configuration used a synthesized sorbent phase containing C18-functionalized graphene–silica particles, which exhibited excellent extraction performance, as well as being reusable and cheaper than commercially available extractive phases. Sequentially, a second setup, based on a multidimensional capillary LC coupled to MS/MS, was assessed for the same purpose. In this case, a graphene oxide-based capillary extraction column (254 µm i.d. × 200 mm) was used as the first dimension, while a C18 analytical capillary column performed the mycotoxin separation in beverages. Although this second one has similarities with the first, we focused mainly on the benefits related to the link between a miniaturized/automated sample preparation device with a capillary LC–MS/MS system, which made our analysis greener. Additionally, the chromatographic efficiency could even be enhanced.

Palladium Nanoparticles-Based Fluorescence Resonance Energy Transfer Aptasensor for Highly Sensitive Detection of Aflatoxin M₁ in Milk

A highly sensitive aptasensor for aflatoxin M₁ (AFM₁) detection was constructed based on fluorescence resonance energy transfer (FRET) between 5-carboxyfluorescein (FAM) and palladium nanoparticles (PdNPs). PdNPs (33 nm) were synthesized through a seed-mediated growth method and exhibited broad and strong absorption in the whole ultraviolet-visible (UV-Vis) range. The strong coordination interaction between nitrogen functional groups of the AFM₁ aptamer and PdNPs brought FAM and PdNPs in close proximity, which resulted in the fluorescence quenching of FAM to a maximum extent of 95%. The non-specific fluorescence quenching caused by PdNPs towards fluorescein was negligible. After the introduction of AFM₁ into the FAM-AFM₁ aptamer-PdNPs FRET system, the AFM₁ aptamer preferentially combined with AFM₁ accompanied by conformational change, which greatly weakened the coordination interaction between the AFM₁ aptamer and PdNPs. Thus, fluorescence recovery of FAM was observed and a linear relationship between the fluorescence recovery and the concentration of AFM₁ was obtained in the range of 5–150 pg/mL in aqueous buffer with the detection limit of 1.5 pg/mL. AFM₁ detection was also realized in milk samples with a linear detection range from 6 pg/mL to 150 pg/mL. The highly sensitive FRET aptasensor with simple configuration shows promising prospect in detecting a variety of food contaminants.

Determination of aflatoxin M1 in milk and dairy products using high performance liquid chromatography-fluorescence with post column photochemical derivatization

The determination of aflatoxin M₁ in milk using high performance liquid chromatography with photochemical post-column derivatization and fluorescence detection is described. The samples were first extracted and clean-up using the immunoaffinity AFLATEST column originally targeted for aflatoxins B₁, B₂, G₁ and G₂. The separation of aflatoxin M₁ were performed using C18 Hypersil gold (150mm×4.6mm, 5μm) column at 40°C under isocratic elution. Fluorescence detector (FLD) was set at 360nm and 440nm as excitation and emission, respectively. The use of methanol to replace acetonitrile as the mobile phase resulted in ∼67% peak area enhancement of AFM₁. The limit of detection (LOD) and quantification (LOQ) of the analytical method after post-column derivatization without evaporation/reconstitution with mobile phase was 0.0085μgL^-1 and 0.025μgL^-1 respectively. However, LOD and LOQ improved to 0.002 and 0.004μgL^-1 respectively with the addition of evaporation/reconstitution step. The method was statistically validated, showing linear response (R²>0.999), good recoveries (85.2-107.0%) and relative standard deviations (RSD) were found to be ≤7%. The proposed method was applied to determine AFM₁ contamination in various types of milk and milk products. Only 2 samples were contaminated with aflatoxin M₁ (10% incidence). However, the contamination level is below the Malaysian and European legislation limits.

Developments in mycotoxin analysis: an update for 2015-2016

This review summarises developments in the determination of mycotoxins over a period between mid-2015 and mid-2016. Analytical methods to determine aflatoxins, Alternaria toxins, ergot alkaloids, fumonisins, ochratoxins, patulin, trichothecenes and zearalenone are covered in individual sections. Advances in proper sampling strategies are discussed in a dedicated section, as are methods used to analyse botanicals and spices and newly developed liquid chromatography mass spectrometry based multi-mycotoxin methods. This critical review aims to briefly discuss the most important recent developments and trends in mycotoxin determination as well as to address limitations of presented methodologies.