Application of the Ultrasonic-Assisted Extraction and Dispersive Liquid–Liquid Microextraction for the Analysis of AFB1 in Egg

Surfactant-Enhanced and Automated Pretreatment Based on Immunoaffinity Magnetic Beads Coupled with Ultra-Performance Liquid Chromatography with Fluorescence Detection for the Determination of Aflatoxins in Peanut Oils

Sample pretreatment is an important step in the detection and analysis of mycotoxins. However, conventional pretreatment methods are complex, time-consuming, and labor-intensive; moreover, they generate a large amount of organic waste that pollutes the environment. An environmentally friendly and automated pretreatment method is proposed. Without extraction using organic solvents in advance, aflatoxins in peanut oil are directly cleaned and concentrated by immunomagnetic beads with the aid of a reaction solution containing surfactant Tween-20. Under optimal conditions, the proposed pretreatment method requires 40 min to simultaneously pretreat 10-24 samples without any centrifugation or filtering steps, and virtually no organic waste was produced. This pretreatment step was coupled with ultra-performance liquid chromatography-fluorescence detection to develop an effective detection method. The recovery of spiked aflatoxins in peanut oils at different concentrations ranged from 91.6 to 100.8%, and the relative standard deviation was below 5.3%. This reliable method overcomes the drawbacks of conventional methods and offers great application prospects.

Simultaneous Determination of Fifteen Polyphenols in Fruit Juice Using Ultrahigh-Performance Liquid Chromatography-Tandem Mass Spectrometry Combining Dispersive Liquid-Liquid Microextraction

Polyphenols are secondary metabolites of plants and used as effective antioxidants in dietary supplements, whose main sources are fruits, vegetables, and grains. To clarify the content and distribution of polyphenols in different fruit species samples accurately, a rapid and sensitive ultrahigh-pressure liquid chromatography-electrospray ionization-tandem mass spectrometry (UPLC-ESI-MS/MS) method combining dispersive liquid-liquid microextraction (DLLME) was developed for quantitative determination of fifteen polyphenol compounds in fruit juice. In this method, the targets were first extracted from 1 g of fruit juice sample using 10 mL of 80% ethanol solution by ultrasonic-assisted extraction (UAE). Then, 1.0 mL of UAE extracted solution, 60 μL of n-octanol and 2.0 mL of H₂O were performed in the following DLLME procedure. A C₁₈ reversed-phase column, ZORBAX SB (100 × 4.6 mm, 3.5 μm), was proposed under gradient elution with 0.1% formic acid aqueous solution and methanol mobile phases for the determination of 15 polyphenols, allowing us to obtain polyphenolic profiles in less than 23.0 min. Under the optimum conditions, the enrichment factors ranged from 162 to 194. The results showed that the 15 polyphenols had linear correlation coefficients (R²) more than 0.99. The limits of detection (LODs) were between 18.3 and 103.5 ng/g, and the average recoveries were between 96.9 and 116.3% with interday relative standard deviations (RSDs) ranging from 4.4 to 8.2% in all cases. The method was successfully applied to the analysis of real fruit juice samples and presented itself as a simple, rapid, practical, and environment-friendly technique.

Determination of aflatoxins in milk sample with ionic liquid modified magnetic zeolitic imidazolate frameworks

The ionic liquid (IL) was introduced to the synthesis system of magnetic zeolite imidazolate framework-8 (M/ZIF-8), which was benefit to the formation of binary imidazole and the co-modification of M/ZIF-8. The morphology and textural properties of ILM/ZIF-8 were characterized by SEM, TEM, BET and BJH. The crystal structural shape and size of MZIF-8 was unvaried with the interventional of IL. The ILM/ZIF-8 was applied to the concentration and determination of aflaoxins (AFB₁, AFB₂, AFG₁ and AFG₂) in milk samples based on magnetic solid phase extraction (MSPE) coupled with ultra high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). The experimental parameters of the MSPE, including amount of ILM/ZIF-8, pH, type and amount of desorption solvent, extraction time and sample volume were investigated by a univariate method and orthogonal screening. The four AFs were concentrated from the 20 mL milk when 90 mg ILM/ZIF-8 was used as magnetic adsorbent. The extraction efficiency of AFs was higher than 80.0% within 15 min. The limits of quantitative and detection were 7.5-26.7 and 2.3-8.1 ng/L, respectively. The proposed method was applied to the determination of milk samples containing trace amounts of AFs and the recoveries ranged from 79.0% to 102.5%, with RSD below 7.7%.