[Determination of 22 mycotoxins in milk by liquid chromatography-quadrupole/orbitrap mass spectrometry].

Mycotoxins have carcinogenic, mutagenic, hepatotoxic, nephrotoxic, immunotoxic, neurotoxic, and teratogenic properties. Thus, these substances have attracted significant attention because they pose a threat to human health. As research on mycotoxins deepens, new structural analogues of mycotoxins are constantly being discovered. In this study, a method based on high performance liquid chromatography-quadrupole/orbitrap mass spectrometry was established for the simultaneous determination of 22 mycotoxins in milk. A simple, effective, and rapid pretreatment method was optimized by focusing on the solvent type, extractant volume, and extracting salt based on the characteristics of the mycotoxins and sample matrix. The analytes were extracted using 0.5% formic acid acetonitrile solution and added with sodium chloride to separate fats from water. The samples were centrifuged at 8000 r/min (4 ℃) for 5 min using a centrifuge and then concentrated using nitrogen. The dry residue was dissolved with 50% methanol aqueous solution. Twenty-two mycotoxins were separated on a ZORBAX Eclipse Plus C18 chromatographic column (100 mm×2.1 mm, 1.7 µm), and quantitative analysis was performed using the isotope internal standard method. The analytes were determined by liquid chromatography-quadrupole/orbitrap mass spectrometry in positive electrospray ionization mode. Qualitative analyses of the compounds were performed in full mass spectrometry/data-dependent tandem mass spectrometry (MS/dd-MS2) mode. Good linearities in the range of 0.5-100.0 µg/L were observed for the 22 mycotoxins, and the correlation coefficients (R2) were greater than 0.999. The limits of detection (S/N=3) and quantification (S/N=10) ranged from 0.3 to 0.5 µg/kg and from 1.0 to 1.5 µg/kg, respectively. The average recoveries of the 22 mycotoxins at three spiked levels of 1.5, 5.0, and 15 µg/kg were between 84.7% and 100.8%, with relative standard deviations (RSDs) of 1.2%-9.9%. These findings indicate that the method has high sensitivity and accuracy as well as good precision. Finally, the method was applied to the detection and analysis of mycotoxins in 25 actual commercial milk samples. The results revealed that the selected samples were not contaminated with any of the mycotoxins analyzed. Thus, the proposed method is useful as a quick preprocessing and confirmatory method for the simultaneous determination of mycotoxins in milk.

An untargeted metabolomics approach to identify markers to distinguish duck eggs that come from different poultry breeding systems by ultra high performance liquid chromatography-high resolution mass spectrometry.

Untargeted metabolomics approach based on ultra high performance liquid chromatography coupled with high resolution mass spectrometry (UHPLC-HRMS) was used to investigate the differences in cage duck eggs and sea duck eggs that from different poultry breeding system, which could help to combat fraud within the egg industry. High dimensions and complex data collected by UHPLC-HRMS were analyzed by multivariate statistical analysis. Identification model of sea duck eggs based on was established. After matching with the chemical databases, four potential markers were putatively matched. Further analysis showed that three of them were confirmed by reference standards. All these three markers (n-behenoyl-d-erythro-sphingosine, 1,2-dipalmitoyl-sn-glycero-3-phosphocholine and n-nervonoyl-d-erythro-sphingosine) have higher content in sea duck eggs. The quantitative analysis showed that the content difference of three markers in farm samples were in highly consistent with the concentration changes measured in experimental samples, which indicate that these three markers are reliable.

A holistic strategy for discovering structural analogues of drug residues in meat using characteristic structural fragments filtering by high-resolution Orbitrap mass spectrometry.

A holistic strategy for discovering structural analogs was established using characteristic structural fragments filtering by high-resolution Orbitrap mass spectrometry and successfully employed for discovering potential hazards in meat. The mass spectrometry fragmentation mechanisms of 113 compounds (including sulphonamides, tetracyclines, benzimidazoles, steroid hormones, cephalosporins, ß-blockers) were investigated and a new strategy for screening of characteristic fragment ions was proposed. To process the data acquired by two scan modes, firstly an integrated filtering strategy was conducted to facilitate the characterisation of multi-class drugs. The integrated filtering strategy was applied to reduce interference in the raw data, which could help extracting the MS1 characteristics of the homolog-type chemical substances and expand the screening of the compounds as effectively as possible. This strategy was based on a combination of nitrogen rule, neutral loss and multiple characteristic fragment ions filtering. The method was validated by rapid screening and identification of targeted compounds in spiked samples. Particularly, the successful detection of several new compounds indicated that this strategy had significant advantages over individual filtration methods and could be a promising method for screening and identifying newly homolog-type drug residues in complex samples.

[Research progress on the fragmentation mechanisms of mass spectrometry soft ionization and screening of chemical hazardous substances in food].

Hazardous chemicals in food are an important cause of food safety problems. Mass spectrometry is an effective tool for the qualitative and quantitative analysis of these substances. In this paper, the fragmentation mechanisms for several chemical hazardous substances, including pesticides, veterinary drugs, mycotoxins, and other chemical pollutants classified by structural analogs, are reviewed. For each class of compounds, we summarize the characteristic fragments and neutral loss generated by cleavage in the mass spectrometry analysis. We also summarize the mechanisms applied to screen and discover new structural analogs in food. This review can help researchers analyze and confirm the structure of compounds and provide a theoretical basis for the discovery of new structural analogs in food.

[Advances in markers reflecting technological conditions in the liquid milk processing].

The trade volume of imported dairy products is increasing with the increase of per capita consumption of dairy products, thus it is the great significant thing to control the quality of dairy products from other countries. The investigation finds that the proline content of imported liquid milk ultra high temperature instantaneous sterilization (UHT) milk (commonly known as normal temperature milk) is significantly higher than that of domestic UHT milk, that a risk of overheating and adding reconstituted milk exists for the imported UHT milk. Although it is currently unable to regulate the source and processing technology of imported dairy products, some certain indicators that reflect the process conditions are often used to monitor the quality of dairy products in the field of heat treatment process control of dairy products. Proline is produced during the processing of dairy products and is a marker that reflects the processing conditions. This paper briefly describes the research status of nine markers used to evaluate in the processing of dairy products at home and abroad, with the aim of providing a theoretical basis for improving the regulatory system for the processing of dairy products in China, and to protect consumer rights.

[Determination of 20 ß -blockers and metabolites in animal-origin foods by ultra performance liquid chromatography-quadrupole electrostatic field orbitrap mass spectrometry].

In this study, ultra performance liquid chromatography-quadrupole electrostatic field orbitrap mass spectrometry was used to establish a high-throughput screening method for 20 ß -blockers and their metabolites in foods of animal origin. The sensitivity and applicability of the established method were improved by optimizing the instrument and pretreatment conditions. The samples were purified by high speed centrifugation at low temperature, and the compounds were separated by a C8 column. Qualitative and quantitative analyses of the compounds were performed in full MS/dd-MS2 (data-dependent MS2) mode. Twenty compounds showed a good linear relationship in the range 0.1-10 µg/L, with correlation coefficients (r2) greater than 0.99. The limits of detection (LODs) ranged from 1 to 5 µg/kg, while the limits of quantification (LOQs) ranged from 2 to 10 µg/kg. The average recoveries were 60.37%-100.84%, with relative standard deviations less than 10%. The method is operationally simple and has good reproducibility and high accuracy, which are essential for ß -blockers and metabolite residue screening in foods of animal-origin.

Analysis of 27 ß-Blockers and Metabolites in Milk Powder by High Performance Liquid Chromatography Coupled to Quadrupole Orbitrap High-Resolution Mass Spectrometry.

This paper presents an application of high performance liquid chromatography coupled with quadrupole orbitrap high-resolution mass spectrometry (HPLC-Q-Orbitrap HRMS) for the analysis of 27 ß-blockers and metabolites in milk powder. Homogenized milk power samples were extracted by acetonitrile and purified by using Oasis PRiME HLB solid-phase extraction cartridges. The Ascentis® C8 chromatographic column was used to separate the analytes. The quantification was achieved by using matrix-matched standard calibration curves with carazolol-d7 and propranolol-d7 as the internal standards. The results show an exceptional linear relationship with the concentrations of analytes over wide concentration ranges (0.5⁻500 µg kg-1) as all the fitting coefficients of determination r² are > 0.995. All the limits of detection (LODs) and quantitation (LOQs) values were within the respective range of 0.2⁻1.5 µg kg-1 and 0.5⁻5.0 µg kg-1. Overall average recoveries were able to reach 66.1⁻100.4% with the intra- and inter-day variability under 10%. This method has been successfully applied to the screening of ß-blockers and metabolites in commercial milk powders. At the same time, the corresponding characteristic fragmentation behavior of the 27 compounds was explored. The characteristic product ions were determined and applied to the actual samples screening.

A high-throughput screening method of bisphenols, bisphenols digycidyl ethers and their derivatives in dairy products by ultra-high performance liquid chromatography-tandem mass spectrometry.

A simple and universal analytical method based on ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) for high throughput screening of 21 bisphenols, bisphenols digycidyl ethers and their derivatives in dairy products was developed. Response Surface Methodology (RSM) was used to optimize sample preparation conditions based on a quick, easy, cheap, effective, rugged and safe (QuEChERS) method. The analytes were extracted by using 15 mL acetonitrile with 1% acetic acid, and the extracts were further purified by using 190 mg of C18 and 390 mg of PSA. The extracts were analyzed by UHPLC-MS/MS with electrospray ionization (ESI) source. Linearity was assessed by using matrix-matched standard calibration and good correlation coefficients (r2 > 0.99) were obtained. The limits of quantitation (LOQs) for the analytes ranged from 0.02 to 5 µg kg-1. The extraction recoveries were in a range of 88.2%-108.2%. Good method reproducibility in terms of intra- and inter-day precision was observed, yielding relative standard deviations (RSDs) less than 8.9% and 9.9%, respectively. The validation method results revealed that the proposed method was sensitive and reliable. Finally, this method was successfully applied to dairy product analysis.

Engineering Cyclodextrin Clicked Chiral Stationary Phase for High-Efficiency Enantiomer Separation.

The separation of racemic molecules is of crucial significance not only for fundamental research but also for technical application. Enantiomers remain challenging to be separated owing to their identical physical and chemical properties in achiral environments. Chromatographic techniques employing chiral stationary phases (CSPs) have been developed as powerful tools for the chiral analysis and preparation of pure enantiomers, most of which are of biological and pharmaceutical interests. Here we report our efforts in developing high-performance phenylcarbamated cyclodextrin (CD) clicked CSPs. Insights on the impact of CD functionalities in structure design are provided. High-efficiency enantioseparation of a range of aryl alcohols and flavanoids with resolution values (Rs) over 10 were demonstrated by per(3-chloro-4-methyl)phenylcarbamated CD clicked CSP. Comparison study and molecular simulations suggest the improved enantioselectivity was attributed to higher interactions energy difference between the complexes of enantiomers and CSPs with phenylcarbamated CD bearing 3-chloro and 4-methyl functionalities.

Synthesis and evaluation of a new Rhodamine B and Di(2-picolyl)amine conjugate as a highly sensitive and selective chemosensor for Al3+ and its application in living-cell imaging.

A new Rhodamine B derivative (RBDPA), namely, N(1)-(2-(3',6'-bis(diethylamino)-3-oxospiro[isoindoline-1,9'-xanthen]-2-yl)ethyl)-N(4),N(4)-bis(pyridin-2-ylmethyl)succinamide, was designed, synthesized and structurally characterized to develop a chemosensor. The studies show that RBDPA exhibits high sensitivity and selectivity toward Al(3+) among many other metal cations in an ethanol/H2O (1:1, v/v, pH=7.2, HEPES buffer, 0.1mM) solution. Fluorescence microscopy experiments further demonstrate that RBDPA can be used as a fluorescent probe to detect Al(3+) in living cells.

A new Rhodamine B-based 'on-off' chemical sensor with high selectivity and sensitivity toward Fe(3+) and its imaging in living cells.

A new fluorescent chemosensor based on a Rhodamine B and pyrrole conjugate (RBPY) has been designed and synthesized. UV-vis absorption and fluorescence spectroscopic studies show that RBPY exhibits a high selectivity and sensitivity toward Fe(3+) among many other metal cations in a MeOH/H2O solution (3:2, v/v, pH 7.10, HEPES buffer, 0.1mM) by forming a 1:1 complex with Fe(3+). Furthermore, results reveal that the formation of the RBPY-Fe(3+) complex is fully reversible in the presence of sulfide anions and could also be used as an efficient sensor for S(2-). Importantly, fluorescence microscopy experiments further demonstrated that RBPY can be utilized as a fluorescent probe for the detection of Fe(3+) in human liver (L-02) cells.

RBAP, a rhodamine B-based derivative: synthesis, crystal structure analysis, molecular simulation, and its application as a selective fluorescent chemical sensor for Sn2+.

A new fluorescent chemosensor based on a Rhodamine B and a benzyl 3-aminopropanoate conjugate (RBAP) was designed, synthesized, and structurally characterized. Its single crystal structure was obtained and analyzed by X-ray analysis. In a MeOH/H2O (2:3, v/v, pH 5.95) solution RBAP exhibits a high selectivity and excellent sensitivity for Sn2+ ions in the presence of many other metal cations. The binding analysis using the Job's plot suggested the RBAP formed a 1:1 complex with Sn2+.

China's food safety regulation and mass spectrometry.

Food safety is essential to people's health and people's livelihood. To ensure that food safety is an important current strategy of the governments, both regulation and standardization are important support for implementing this strategic initiative effectively. The status and prospects of China's food laws, regulations, and standards system are introduced. China now has established a complete law regime providing a sound foundation and good environment for keeping the health of people, maintaining the order of social economy and promoting the international trade of food. At the same time, it is undoubtedly important to strengthen standardization and improve the food safety standards system. In the administration of food safety, mass spectrometry is becoming more and more important and many analytical methods developed in China are based on its application.