Se pu = Chinese journal of chromatography最新文献

A research-project-based open instrumental-analysis experiment was designed for undergraduate teaching led by the attributes of an environmental science major. In this experiment， porous monolithic fibers are in-situ synthesized from 9-vinylanthracene and styrene （as a monomer mixture） based on the molecular characteristics of studied polycyclic aromatic hydrocarbons （PAHs）， and then used as an extractant for solid-phase microextraction （SPME）. A method for reliably monitoring PAHs in environmental water samples was developed by combining SPME with high performance liquid chromatography （HPLC）. Students designed and constructed a complete experimental instrumental-analysis process， which included preparing and characterizing the monolith fibers， optimizing the SPME conditions， preparing environmental water samples， and analysis by HPLC. Guided by teachers， undergraduates learned relevant knowledge prior to performing the experiment， improved their operating skills during the experiment， analyzed data， and wrote research reports during the latter stage of the course. Undergraduates' interest is stimulated by completing the experiment， while scientific thinking， analysis， and problem-solving abilities are concurrently improved and cultivated. The present course also lays the foundation for cultivating future high-quality environmental-science talents.

According to the Safety and Technical Specification for Cosmetics （2015）， the addition of chemical drugs to cosmetics is strictly prohibited. Anti-alopecia cosmetics are often found to contain illegal additions of prohibited drugs such as minoxidil， finasteride and other substances. Ultra-high performance liquid chromatography-tandem triple quadrupole-linear ion trap mass spectrometry （UHPLC-Q-TRAP/MS） has become a powerful technology for the simultaneous detection of illegal ingredients in cosmetics due to its advantages of rapid analysis， high sensitivity， high throughput and high selectivity. An ultra-high performance liquid chromatography-multiple reaction monitoring-information dependent acquisition-enhanced production scanning （UHPLC-MRM-IDA-EPI） method was developed to determine 13 JAK inhibitors in anti-alopecia cosmetics， including baricitinib， tofacitinib， ritlecitinib， peficitinib， abrocitinib， upadacitinib， ivarmacitinib， fedratinib， filgotinib， ruxolitinib， momelotinib， pacritinib and bozitinib. The influence of extraction solvents was investigated. Approximately 0.2 g of the sample was weighed and placed in a 50 mL graduated centrifuge tube with a cap. Then， 2 mL of 0.1% （v/v） aqueous formic acid and 10 mL of acetonitrile were added， followed by vortexing for 1 min. Subsequently， the mixture was sonicated in an ultrasonic bath for 15 min. Added 0.5 g of sodium chloride， and the mixture was centrifuged at 8 000 r/min for 8 min at 5 °C. The supernatant was transferred to another 50 mL graduated centrifuge tube with a cap. The residue was added with 10 mL of acetonitrile and the extraction procedure was repeated. After high-speed centrifugation， the supernatant was combined. The combined supernatant was added with 0.2 g of sodium chloride， and the mixture was frozen at ‒20 °C for 1 h. It was centrifuged at 8 000 r/min for 5 min at 5 °C. The acetonitrile layer was collected and filtered through a 0.22 μm organic filter membrane. The initial filtrate was discarded， and the subsequent filtrate was collected as the sample solution. A C₁₈ column was used for chromatographic separation， enabling the successful separation of the analytes within 10 min. The mobile phase consisted of 0.1% （v/v） aqueous formic acid and acetonitrile， with gradient elution applied to optimize separation efficiency. The flow rate was set at 0.3 mL/min， and the column temperature was maintained at 40 ℃ to ensure consistent performance. A fixed injection volume of 2 μL was used to guarantee reproducibility and accuracy in the analysis. This configuration enabled the rapid and reliable separation of the target compounds. For the analysis of the 13 kinds of JAK inhibitors， an ESI source operating in positive ion mode was used with MRM-IDA-EPI detection. Quantification was performed by the external standard method using matrix-matched standard solutions. Good separation of the 13 JAK inhibitors was achieved under the optimized chromatographic conditions

Photoinitiators are indispensable components in the formulation of inks used for printing packaging materials. Residual photoinitiators on the surface of packaging materials may migrate and contaminate the contents， posing potential risks to human health. Toxicological experiments have shown that photoinitiators pose various risks， including carcinogenicity， reproductive toxicity， and dermal toxicity. However， current quality standards for pharmaceutical packaging materials， both domestically and internationally， do not impose limits on photoinitiators. This study focuses on 12 photoinitiators， which are either restricted or prohibited in certain fields such as food packaging materials. The selected medicinal composite membranes， widely employed in pharmaceutical packaging and requiring significant ink volumes， serve as representative samples. This research holds significant implications for improving the quality standards of pharmaceutical packaging materials and ensuring medication safety. While gas chromatography-mass spectrometry and ultra performance liquid chromatography-tandem mass spectrometry have been reported for photoinitiators detection， UPC²-MS/MS has not yet been reported for detecting these compounds. The principle of UPC² is based on supercritical fluid chromatography， where the mobile phase primarily consists of supercritical CO₂ with a minimal use of organic solvents， aligning with the trend of green chemistry. When coupled with MS， this method also enhances the sensitivity of detection. Therefore， a novel method based on UPC²-MS/MS was established for the determination of the 12 photoinitiator residues in medicinal composite membranes. MS conditions， makeup solution conditions （solvent， additive type， additive ratio， flow rate）， and sample pretreatments were systematically optimized. Photoinitiator residues were extracted from the medicinal composite membranes using acetonitrile by ultrasonication. The chromatographic separation was achieved on a UPC² CSH^TM Fluoro-Phenyl column （100 mm × 3.0 mm， 1.7 μm） under gradient elution using a mobile phase composed of supercritical carbon dioxide （A） and methanol （B）. Gradient elution was performed as follows： 0-1.5 min， 100%A-95%A； 1.5-2.0 min， 95%A-80%A； 2.0-3.0 min， 80%A-70%A； 3.0-4.0 min， 70%A-100%A； 4.0-5.0 min， 100%A. A methanol-water （99∶1， v/v） mixture was employed as the makeup solution to enhance MS response. The mobile phase flow rate， makeup solution flow rate， column temperature， and injection volume were respectively set at 1.5 mL/min， 0.2 mL/min， 50 ℃ and 1 μL. The automatic back pressure regulator maintained 13.79 MPa. The 12 photoinitiators were monitored in multiple reaction monitoring （MRM） mode with electrospray ionization （ESI） under positive conditions. Quantification was performed using the external standard method. The results showed that all 12 photoinitiators exhibited good linear relations

Experimental teaching， serving as a bridge between theoretical knowledge and practical competence， can deepen students' understanding of theoretical concepts， and enhance their ability to solve complex problems， thereby playing a pivotal role in cultivating elite chemistry talents for the national innovation system. By understanding the laws of higher education development and innovative talent growth， the Chemistry Experiment Teaching Center of the College of Sciences at Northeastern University has innovatively proposed a closed-loop teaching model： "Construction Supports Competitions-Competitions Nurture Teaching-Teaching Promotes Learning"， aiming at the problem of difficult barrier between scientific research and pedagogy in talent development. This model is based on the requirements for cultivating top innovative talents， leveraging the practical feedback of disciplinary competitions， and creating a dynamic feedback mechanism of "Competition Incubation→Teaching Transformation→Competency Feedback". Taking the award-winning project "Micro-Plasma Emission Spectrometer Setup and Trace Element Analysis Experiment" from the Chemistry Innovation Design Competition as an example， this study demonstrates the model's breakthrough in traditional experimental teaching. Through a 4-class-hour experimental course， students independently construct a dielectric barrier discharge （DBD） micro atomic emission spectroscopy device， combined with hydride generation （HG） introduction technology to complete trace arsenic detection. The method showed a good linear relationship in the mass concentration range of 20-500 μg/L， with a coefficient of determination （R²） of 0.997. Teaching practice shows that students deepened their understanding of principles and made the instrument structure transparent through hands-on construction， promoting the improvement of teaching quality and providing a scalable innovative paradigm for the "high-order， innovative， and challenging" curriculum reform.

Bisphenols （BPs）， which include bisphenol A and its analogs （such as bisphenol S， bisphenol AF， and bisphenol B）， are chemical substances that are synthesized artificially. BPs are used in epoxy resins and polycarbonate plastics and are widely found in food packaging and beverage containers. BPs are endocrine disruptors； hence， they can disrupt the natural hormonal activities of the human body， impact the neurological development of children， and affect intestinal microbial communities in the body， leading to obesity. Consequently， BPs pose threats to human health. The prepared dishes are usually using plastic packaging （containers， films， tubes， etc.）； consequently， BPs migrate from the packaging material to the food in the container is hot topic of wide concern. To address this issue， an efficient， simple and accurate method for the simultaneous determination of the 15 BPs content levels in prepared dishes using ultra performance liquid chromatography-tandem mass spectrometry （UPLC-MS/MS） was developed. The effects of the extraction solvent and its proportion， the amount of weighed matrix， and type of purifying agent on the responses and recoveries of the 15 BPs were investigated under the optimized MS conditions with the aim of determining the optimal sample-preparation conditions. The prepared dishes samples were crushed and evenly mixed， after which an internal standard solution containing a mixture of bisphenols was added and dispersed using 2.0 mL of ultrapure water. Acetonitrile （8.0 mL） was subsequently added， and the sample was extracted using vortex ultrasonication， centrifuged at 10 000 r/min for 10 min， and a 3.0-mL aliquot of the centrifuged supernatant was cleaned using a Captiva EMR-Lipid clean-up column， after which the purified liquid was subjected to UPLC-MS/MS. Analyses of response values， separation effects， and chromatographic peak shapes revealed that the Waters ACQUITY HSS T₃ column （100 mm×2.1 mm， 1.8 μm） optimally separated the 15 target BPs at a column temperature of 40 ℃， a flow rate of 0.2 mL/min， and an injection volume of 2.0 μL. A Waters ACQUITY BEH C₁₈ column （50 mm×2.1 mm， 1.7 μm） was used to trap and eliminate interference from exogenous BPs in the piping components. Gradient elution was performed using methanol and 0.01% （v/v） aqueous ammonia as mobile phases. Data were collected in electrospray negative-ion （ESI^-） and multiple reaction monitoring （MRM） modes， and quantified using the isotope internal standard method. The 15 BPs exhibited good linear relationships within their respective linear ranges under the optimized experimental conditions， with correlation coefficients （R²） greater than 0.999 0. The limits of detection （LODs） and limits of quantification （LOQs） were in the range of 0.01-0.45 μg/kg and 0.03-1.50 μg/kg， respectively. The recoveries and relative standard deviations （RSDs） of the 15 BPs in matrix sample of prepared dishes at low， medium

With the rapid advancement of industrialization， agricultural intensification， and urbanization， issues pertaining to environmental pollution and food safety have become increasingly prominent. The use of pesticides plays a vital role in augmenting agricultural yield and quality， thereby serving as a foundational element of modern agriculture. However， improper or excessive application can lead to pesticide residues， which pose a significant threat to ecological systems and human health. Therefore， it is essential to enhance the surveillance of pesticide residue levels and to pioneer novel， efficient analytical methodologies. Sample pretreatment constitutes a crucial stage in the detection pipeline. Consequently， the development of rapid， green， and efficient sample pretreatment techniques has advanced significantly and gained widespread application in recent years. To effectively monitor pesticide residues in fruits and vegetables while reducing matrix interference， we established a high-throughput method for detecting 34 pesticides and their metabolites. This method utilizes a modified QuEChERS approach with carboxylated multi-walled carbon nanotubes （MWCNTs-COOH） as a clean-up sorbent， followed by analysis with gas chromatography-tandem mass spectrometry （GC-MS/MS）. The detection conditions for 34 pesticide and metabolite residues in fruits and vegetables were established through the optimization of the pretreatment process， chromatographic conditions， and mass spectrometry parameters. Specifically， fruit and vegetable samples were homogenized and extracted using a commercial QuEChERS EN extraction kit. Following shaking and centrifugation， the supernatant was transferred to a purification tube containing 10 mg of MWCNTs-COOH. Subsequently， this supernatant was evaporated to near-dryness under a gentle stream of nitrogen， reconstituted in ethyl acetate containing an internal standard， and filtered through a 0.22 μm nylon membrane filter. The target substances were separated on a HP-5MS UI quartz capillary column （30 m×0.25 mm×0.25 μm） with a programmed temperature gradient， detected by GC-MS/MS in multiple reaction monitoring （MRM） mode， and quantified using a matrix-matched internal standard calibration method. A full scan was performed across an m/z range of 45-500. Retention times and characteristic fragment ions were identified using the NIST mass spectral library. The most intense fragment ion was selected as the precursor ion. Parameters including dwell time and collision energy were then optimized to select the optimal product ion for each transition. Acetonitrile was selected as the optimal extraction solvent， and 10 mg was determined to be the optimal dosage of MWCNTs-COOH for purification. Under the optimized conditions， all 34 pesticides and metabolites demonstrated good linearities within their respective concentration ranges， with correlation coefficients （R²） greater than 0.997 4. The method demonst

Isoxazoline drugs （ISOs） are a class of five-membered heterocyclic compounds containing N and O atoms. They can inhibit γ-aminobutyric acid gated chloride channels and are widely used in the treatment of parasitic diseases in poultry. The intake of animal-derived foods by humans is an important way to come into contact with ISOs. Excessive use of ISOs can lead to their residues in animal-derived foods， thereby threatening human health and causing neurotoxicity and hepatotoxicity. To address the safety issues caused by ISO residues in animal-derived foods， an ultra-high performance liquid chromatography-quadrupole/linear ion trap mass spectrometry （UHPLC-Q/Trap MS） analytical method for four novel ISOs （fluralaner， sarolaner， afoxolaner， lotilaner） in bovine-origin foods （including milk， beef and bovine liver） was established. The sample was first extracted with acetonitrile and then purified with PRiME HLB solid phase extraction （SPE） column. Using 5 mmol/L ammonium acetate aqueous solution and acetonitrile as the mobile phase， after separation by Shim-pack GIST C18-AQ （100 mm×2.1 mm， 2.7 μm） chromatography column， the analysis was carried out in the multi-reaction monitoring （MRM） mode by information-dependent acquisition （IDA）， enhanced product ion scanning （EPI） and spectral library retrieval， and quantification was performed using the external standard method. The results showed that the four ISOs had good linear relationships within their respective mass concentration ranges. The correlation coefficients （r） were all ≥0.993 6， and the limits of detection （LODs） and quantification （LOQs） were 0.2-0.5 μg/kg and 0.5-1.0 μg/kg， respectively. Under the low， medium and high spiked levels （1， 2 and 10 μg/kg）， the recoveries of the four ISOs ranged from 67.6% to 118.9%， and the relative standard deviations （RSDs） ranged from 2.0% to 20.0%. In addition， in this study， qualitative screening and analysis of the target compounds were conducted through MRM-IDA-EPI combined with spectral library retrieval. Dual qualitative analysis of the target compounds was carried out based on information such as retention time and EPI fragment ions， which improved the accuracy of qualitative analysis and effectively eliminated the interference of false positive results. This method features low LODs and good recoveries. It is also simple and rapid to operate， with high sensitivity and accuracy. It can achieve qualitative and quantitative analysis of new ISOs residues in bovine-origin foods. This study can provide technical support for food safety agencies to implement preventive measures against new ISOs in animal foods.