A monolithic column based on covalent cross-linked polymer gels for online extraction and analysis of trace aflatoxins in food sample

Simultaneous determination of twelve mycotoxins in edible oil, soy sauce and bean sauce by PRiME HLB solid phase extraction combined with HPLC-Orbitrap HRMS

A solid phase extraction-high-performance liquid chromatography-tandem Orbitrap high resolution mass spectrometry (HPLC-Orbitrap HRMS) method was established for the determination of 12 mycotoxins (ochratoxin A, ochratoxin B, aflatoxin B1, aflatoxin B2, aflatoxin G1, aflatoxin G2, HT-2 toxin, sterigmatocystin, diacetoxysciroenol, penicillic acid, mycophenolic acid, and citreoviridin) in edible oil, soy sauce, and bean sauce. Samples were extracted by 80:20 (v:v) acetonitrile-water solution, purified by PRiME HLB column, separated by aQ C18 column with mobile phase consisting of 0.5 mmol/L ammonium acetate-0.1% formic acid aqueous solution and methanol. The results showed that the limits of detection (LODs) and limits of quantification (LOQs) of 12 mycotoxins were 0.12–1.2 μg/L and 0.40–4.0 μg/L, respectively. The determination coefficients of 12 mycotoxins in the range of 0.20–100 μg/L were > 0.998. The average recoveries in soy sauce and bean sauce were 78.4–106.8%, and the relative standard deviations (RSDs) were 1.2–9.7% under three levels, including LOQ, 2× LOQ and 10 × LOQ. The average recoveries in edible oil were 78.3–115.6%, and the precision RSD (n = 6) was 0.9–8.6%. A total of 24 edible oils, soy sauce and bean sauce samples were analyzed by this method. AFB1, AFB2, sterigmatocystin and mycophenolic acid were detected in several samples at concentrations ranging from 1.0 to 22.1 μg/kg. The method is simple, sensitive, and rapid and can be used for screening and quantitative analysis of mycotoxin contamination in edible oil, soy sauce, and bean sauce.

Application of calcium oxide as an efficient phase separation agent in temperature-induced counter-current homogenous liquid-liquid extraction of aflatoxins from dried fruit chips followed by high-performance liquid chromatography-tandem mass spectrometry determination

A temperature-induced counter-current homogenous liquid-liquid extraction procedure performed in a burette has been proposed for the isolation of aflatoxins B1, B2, G1, and G2 from various fruit chip samples. In this method, a homogenous solution of deionized water and cyclohexylamine is added to the solid sample and the resulted mixture is vortexed. In the following, the liquid phase is taken and passed through the burette filled with a mixture of calcium oxide (as a phase separation agent) and sand (to avoid clumping the calcium oxide). By doing so, the temperature of the solution is increased by hydration of calcium oxide and consequently, the homogenous state is broken and the aflatoxins are migrated into the resulted tiny droplets of cyclohexylamine. This phase is collected on the top of the solution owing to its low density with respect to an aqueous solution. Numerous parameters which can affect the efficiency of the suggested approach were evaluated and under the best situations, great repeatability, low limits of determination and quantification, and high extraction recoveries were acquired. In the end, the suggested approach was employed for the quantification of the selected aflatoxins in various fruit chips samples marketed in Tabriz City, Iran.

[Synthesis and application progress of covalent organic polymers in sample preparation for food safety analysis]

Food safety is closely related to human health and life. Contaminated foods may result in illness or poisoning. For example, perfluorinated compounds can concentrate in the human body, or they can be transferred to the baby during breastfeeding, thus leading to serious health risks. Phthalate esters may cause damage to the liver, lungs, and kidneys. Therefore, food safety has become a hot topic at a global level. Poisonous and harmful substances in foods are derived from the environment, planting or breeding, food contacting materials, and food processing, or due to unsuitable storage conditions. Residues of pesticides and veterinary drugs, organic pollutants, additives, heavy metals, and biotoxins often hamper food safety, causing diseases or even death. The diversity of available food species, complexity of the sample matrix, and lack of information about the source of pollutants render the direct determination of food contaminants difficult. Pretreatment is vital for the accurate analysis of trace toxins in foods. Optimal pretreatment can not only improve the extract efficiency and determination sensitivity, but also prevent instrument contamination. Pretreatment techniques have played an important role in trace determination for complex matrices. Pretreatment methods can be classified as solvent-based and adsorption-based methods. Adsorption-based techniques such as solid-phase extraction, magnetic solid-phase extraction, and solid-phase microextraction are simple and efficient, and hence, are widely used. In these pretreatment techniques, adsorbents play a key role in the extraction effect. In the last few years, metal organic frameworks, metal oxide materials, carbon nanotubes, graphene, and magnetic nanoparticles, as well as a combination of these materials, have been used as adsorbents. These materials are porous and have a large surface area; they are used to enrich trace targets and eliminate interferents. Covalent organic polymers (COPs) are a class of organic porous materials constructed from organic monomers via covalent bonding. Given their excellent characteristics such as light density, good stability, high surface area, structural controllability, and ease of modification, COPs are potential adsorbents. COPs are often synthesized by solvent thermal methods. However, these methods are time-consuming and require toxic solvents and harsh reaction conditions. As alternatives, room-temperature methods, mechanical chemical methods, microwave-assisted methods, and UV-assisted methods have been developed. This has facilitated the synthesis of a wide range of COPs. In this article, the recent applications of COPs in sample pretreatment for food safety analysis are reviewed. COPs can be used in solid-phase extraction by simple packing into columns, polymerization, or chemical bonding in the capillary. Magnetic compounds have been prepared by one-pot synthesis, in situ growth, in situ reduction, or coprecipitation methods and used in magnetic solid-phase extraction. Coatings of solid-phase microextraction fibers are fabricated by physical methods, chemical bonding, sol-gel methods, or in situ growth. Toxic and harmful substances in foods and foodstuffs are efficiently extracted by exploiting the high adsorbent capacities and specificity of COPs. Future development prospects and challenges in sample pretreatment are also discussed herein. There is increased focus on the development of simple, efficient, and environment-friendly methods to synthesize COPs with specific functions; further, high-throughput, sensitive analytical methods may be established. In the future, more specific COPs will be prepared in a cost-effective manner for widespread use in sample pretreatment.

Evaluation of the tubing material and physical dimensions on the performance of extraction columns for on-line sample preparation-LC-MS/MS

Nowadays, high analytical throughputs are required considering an increasing demand for faster, simple and improved methods to analyze contaminants in a considerable number of samples. Generally, these compounds are present in complex matrices in contact with a high number of interferents becoming their determination difficult at low concentration. In this context, on-line extraction techniques arose to improve the extraction as well as separation power, while minimizing errors related to human sample manipulation. This paper describes a study regarding the development and optimization of columns used as an extraction device in multidimensional liquid chromatography. The main goals were the evaluation of the material used as column body as well as the investigation of the tube dimensions (internal diameter and length) in the extraction performance. Firstly, several tube materials were tested (steel, fused silica, PEEK, among others) being steel whose reported the best performance and was consequently chose for further studies. The investigation about the effects of the columns physical dimensions revealed a linear relationship between performance and the amount of sorbent utilized as extractive phase. However, when different columns with same amount of sorbent were tested results suggests that both i.d. and lengths play an important role in extraction efficiency. The longest columns with lower internal diameter showed the best results favoring the radial as well as axial analytes diffusion into the extraction column. After evaluation of these column variables, applications were carried out employing several different analytes belonging to various chemical classes and practical utilization, in order to reinforce the versatility as well as the robustness of this proposed study.

Developments in mycotoxin analysis: an update for 2017-2018

This review summarises developments that have been published in the period from mid-2017 to mid-2018 on the analysis of various matrices for mycotoxins. Analytical methods to determine aflatoxins, Alternaria toxins, ergot alkaloids, fumonisins, ochratoxins, patulin, trichothecenes, and zearalenone are covered in individual sections. Advances in sampling strategies are discussed in a dedicated section, as are methods used to analyse botanicals and spices, and newly developed comprehensive liquid chromatographic-mass spectrometric 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 the presented methodologies.

Current status and future trends on automated multidimensional separation techniques employing sorbent-based extraction columns

Determination of target analytes present in complex matrices requires a suitable sample preparation approach to efficiently remove the analytes of interest from a medium containing several interferers while at the same time preconcentrating them aiming to improve the output signal detection. Online multidimensional solid-phase separation techniques have been widely used for the analysis of different contaminants in complex matrices such as food, environmental, and biological samples, among others. These online techniques usually consist of two steps performed in two different columns (extraction and analytical column), the first being employed to extract the analytes of interest from the original medium and the latter to separate them from the interferers. The extraction column in multidimensional techniques presents a relevant role since their variations as building material (usually a tube), sorbent material, modes of application, and so on can significantly influence the extraction success. The main features of such columns are subject of constant research aiming improvements directly related to the performance of the separation techniques that utilize multidimensional analysis. The present review highlights the main features of extraction columns online coupled to chromatographic techniques, inclusive for in-tube solid-phase microextraction, online solid phase and turbulent flow, aiming the determination of analytes present at very low concentrations in complex matrices. It will critically describe and discuss some of the most common instrumental set up as well as comments on recent applications of these multidimensional techniques. Besides that, the authors have described some properties and enhancements of the extraction columns that are used as first dimension on these systems, such as type of column material (poly (ether ether ketone), fused silica, stainless steel, and other materials) and the way that the extractive phase is accommodated inside the tubing (filled and open tubular). Practical applications of this approach in fields such as environment, food, and bioanalysis are also presented and discussed.