Organic ultraviolet absorbers （OUVAs） are a class of emerging contaminants that have garnered significant attention in recent years. In response to the characteristics of high detection frequency and low concentrations of OUVAs in water bodies， this study established an analytical method based on solid phase extraction （SPE） coupled with ultra-high performance liquid chromatography-tandem mass spectrometry （UHPLC-MS/MS） for the simultaneous determination of 16 OUVAs （nine UV stabilizers and seven UV filters） in drinking water. The 500 mL water sample was pretreated with 25 mg ascorbic acid， acidified to pH 2-3， and spiked with 1 mL of 5 μg/L mixed internal standard working solution. Target compounds were enriched and concentrated using an HLB solid phase extraction cartridge （200 mg/6 mL）. Separation was achieved on an Acquity Premier BEH C₁₈ column （100 mm×2.1 mm， 1.7 μm） using a gradient elution with methanol and 2 mmol/L ammonium acetate aqueous solution as the mobile phases. Detection was performed using electrospray ionization in positive mode and multiple reaction monitoring （MRM）， with quantification carried out by the internal standard method. The precision and accuracy of the established method were evaluated using drinking water as the matrix. The results showed that all 16 OUVAs exhibited good linearity within their respective mass concentration ranges， with correlation coefficients （r） greater than 0.992. The method detection limits （MDL， S/N=3） were 0.03-5 ng/L， and the method quantification limits （MQL， S/N=10） were 0.1-15 ng/L. At spiked levels of 5， 20 and 50 ng/L， the recoveries of the target analytes ranged from 75.0% to 130.6%， with relative standard deviations （RSDs） ranging from 0.9% to 12.9% （n=6）. A total of seven source water samples and seven drinking water samples were analyzed using this method. The results showed that two OUVAs， 2-hydroxy-4-methoxybenzophenone （UV-9） and octocrylene （OC） were detected. In source water， the mass concentrations of UV-9 ranged from <MQL to 13.4 ng/L， while OC mass concentrations ranged from 5.0 to 32.23 ng/L. In drinking water， UV-9 was detected at 0.4 ng/L， and OC mass concentrations ranged from <MQL to 13.2 ng/L. This method is suitable for the trace analysis of 16 OUVAs in drinking water， demonstrating good accuracy and precision. It effectively improves the detection efficiency of OUVAs in water and can be used for the environmental monitoring and analysis of OUVAs in drinking water in China.

p-Phenylenediamine compounds （PPDs） are widely used as anti-aging agents and antioxidants in rubber industry. However， environmental concerns have arisen regarding the toxicity of their quinone derivatives （PPD-Qs）. Fine particulate matter （PM_2.5） serves as a crucial vector enabling PPDs and PPD-Qs to enter the human body via respiratory exposure pathway. Therefore， accurate monitoring of PPDs and PPD-Qs in PM_2.5 is essential. In this research， a high performance liquid chromatography-tandem mass spectrometry （HPLC-MS/MS） approach was established to quantify seven PPDs and seven PPD-Qs in PM_2.5. Samples were collected on quartz fiber filters with a diameter of 90 mm. The filter was cut into strips and subsequently spiked with 2 ng of 6PPD-d₅ and 6PPD-Q-d₅ internal standards. The target compounds were extracted with 10 mL of acetonitrile containing 1% （volume fraction） ammonia solution and 20 μmol/L glutathione （GSH）， and purified via a modified QuEChERS pretreatment method. Specifically， after salting out with 0.5 g of NaCl and 1.0 g of MgSO₄， the supernatant was subjected to dispersive solid-phase extraction for cleanup. In this process， 0.5 g of MgSO₄， 100 mg of octadecylsilane （C₁₈）， and 100 mg of N-propylethylenediamine （PSA） were employed as sorbents. Subsequently， 5 mL of the cleaned-up supernatant was evaporated to near dryness and then redissolved in 0.2 mL of a methanol-water mixture （1∶1， volume ratio） for instrumental determination. The compounds were separated on a Waters ACQUITY UPLC HSS T₃ column（100 mm×2.1 mm，1.8 μm） with mobile phases consisting of a 5 mmol/L ammonium formate aqueous solution containing 0.1% formic acid and methanol. Identification and quantification of the compounds were carried out under positive electrospray ionization in multiple reaction monitoring mode. The results indicated that all analytes exhibited good linear relationships within the range of 0.05-20.0 ng/mL， with correlation coefficients （r） exceeding 0.999. The method detection limits （MDLs） and method quantification limits （MQLs） of the compounds were within the ranges of 0.003-0.07 pg/m³ and 0.01-0.2 pg/m³， respectively. At three spiked levels of low， medium and high， the recoveries of the compounds were in the range of 66.3% to 119.0% ， and the relative standard deviations （RSDs） ranged from 1.5% to 13.2% （n=6）. Ultimately， the developed method was employed for the analysis of PPDs and PPD-Qs in PM_2.5 samples collected from Baotou during January and February 2025. The results indicated that seven PPDs and five PPD-Qs were detected， with mass concentrations ranging from 2.26 to 251.2 pg/m³ and 2.36 to 105.4 pg/m³， respectively. The proposed method is characterized by its simplicity， environmental friendliness and accuracy， making it suitable for the rapid quantitative analysis of PPDs and PPD-Qs in PM_2.5.

Alkaloids represent a class of naturally-occurring nitrogen-containing compounds widely distributed across diverse plant species. Owing to their well-documented potential to induce adverse effects on human health， certain alkaloids are explicitly prohibited from being used in cosmetic formulations. The escalating global popularity of essential oil-based cosmetics， which commonly incorporate complex botanical extracts， presents a potential avenue for the inadvertent introduction of these prohibited substances. Consequently， the development of robust， sensitive， and efficient analytical methods for their monitoring is of utmost significance for consumer safety and regulatory compliance. This study devises a reliable， high-throughput approach for the simultaneous determination of 13 prohibited alkaloids in essential oil-based cosmetics. It integrates optimized QuEChERS sample preparation with ultra performance liquid chromatography-tandem mass spectrometry （UPLC-MS/MS）. The sample preparation procedure was meticulously designed to maximize efficiency and minimize analyte loss. Chromatographic separation was accomplished on a Waters ACQUITY UPLC HSS T3 column （100 mm × 2.1 mm， 1.8 μm） maintained at a constant temperature of 30 ℃. The mobile phase was composed of （A） acetonitrile and （B） 0.1% （volume fraction） formic acid aqueous solution. A gradient elution program was implemented at a stable flow rate of 0.3 mL/min according to the following profile： an initial 5， a linear increase to 15 （0-2 min）， a rapid rise to 70 （2-4.5 min）， followed by an immediate reversion to the initial 5 （4.5-5.5 min）， which was maintained for re-equilibration until 7.0 min. The injection volume was 5 µL. Detection and quantification were conducted using a triple quadrupole mass spectrometer equipped with an electrospray ionization （ESI） source operating in positive ion mode （ESI⁺）. Data acquisition was carried out in the multiple reaction monitoring （MRM） mode to ensure superior specificity and sensitivity. For each of the 13 alkaloids， two specific ion transitions were monitored： one for quantitative analysis and the other for confirmatory identification. The method was rigorously validated in accordance with accepted analytical guidelines. All 13 target alkaloids displayed excellent linearity within a mass concentration range of 0.2 to 50 ng/mL， with correlation coefficients （R²） consistently exceeding 0.99. The limits of detection （LODs） and limits of quantification （LOQs）， determined with acceptable accuracy and precision， ranged from 1 µg/kg to 4 µg/kg and 2 µg/kg to 10 µg/kg， respectively. Method accuracy and precision were assessed through recovery tests at three spiking levels， with six replicates at each level. The mean recoveries for all analytes ranged from 83.9% to 119.1%， with associated relative standard deviations （RSDs） all being ≤7.3%， validating the method’s high reliability and repeatability. Systematic evaluation indicated that the matrix effects for the 13 analytes were negligible； hence， the solvent calibration curve was adopted for quantitative analysis. The practical applicability of the validated method was demonstrated through the analysis of 50 batches of commercially available essential oil-based cosmetics. This market survey encompassed 15 products specifically marketed for infants or children and 35 products intended for adult use. As a result， none of the 13 target prohibited alkaloids were detected in any of the tested samples above their respective LOQs. A particularly notable accomplishment of this work is the successful development of a sensitive and reliable quantification strategy for oleandrin， a potent cardiotoxic alkaloid for which standardized detection methods in complex cosmetic matrices such as essential oils have been conspicuously absent. In conclusion， this study successfully establishes a simple， rapid， sensitive， and robust QuEChERS-UPLC-MS/MS method. It is comprehensively validated and clearly well-suited for the routine screening， risk monitoring， and quality control of 13 prohibited alkaloids in a wide array of essential oil-based cosmetics. The method offers reliable technical support for regulatory bodies to enforce safety standards and for manufacturers to ensure the safety and compliance of their products， thereby effectively contributing to the protection of consumer health.

A supercritical fluid chromatography （SFC） method coupled with UV detection was developed for the separation of linagliptin and its S-enantiomer. The method was validated and successfully applied to detect the S-enantiomer in real pharmaceutical samples. The separation of the enantiomer was investigated using six different chromatographic columns， and different cosolvents were studied. Chromatographic conditions， including column temperature， backpressure， and flow rate， were optimized. The DAICEL CHIRALPAK AD-H column （250 mm×4.6 mm， 5 μm） was used for separation. Supercritical CO₂ served as mobile phase A， and ethanol-isopropanol （1∶1， volume ratio） containing 0.25% diethanolamine and 0.25% trifluoroacetic acid was used as mobile phase B. Isocratic elution was carried out at a ratio of A∶B=73∶27 （volume ratio） with a flow rate of 1.5 mL/min. The column temperature was set at 40 ℃， back pressure at 15 MPa， injection volume at 6 μL， and detection wavelength at 220 nm. Under these conditions， linagliptin and its S-enantiomer were separated with a resolution of 3.1 and good peak shapes. Both linagliptin and its S-enantiomer exhibited good linearity in the concentration range of 2–90 μg/mL， with correlation coefficients of 0.999　7 and 0.999　9 （n=8）， respectively. The limit of detection （LOD） for both was 0.8 μg/mL （S/N=3）， and the limit of quantification （LOQ） for both was 2 μg/mL （S/N=10）. The average recoveries of the S-enantiomer spiked at low， medium， and high concentrations in active pharmaceutical ingredients and tablets were 97.4% （RSD=1.1%， n=9） and 101.6% （RSD=1.2%， n=9）， respectively. S-Enantiomer was not detected in three batches of active pharmaceutical ingredients or in three batches of tablets from two different manufacturers. This study represents the first application of SFC for the separation of linagliptin and its S-enantiomer. The method is environmentally friendly， sensitive， and highly efficient， offering good repeatability of peak area. It provides a solid foundation for the quality control of linagliptin and the inclusion of the SFC method in pharmaceutical quality standards， while also offering a useful approach for the rapid separation and impurity control of other chiral drugs.

Organic phosphate esters （OPEs） and phthalate esters （PAEs） are two classes of synthetic compounds widely incorporated into various industrial and consumer products as flame retardants and plasticizers. Both exhibit multi-organ cumulative toxicity. In this study， an ultra performance liquid chromatography-tandem mass spectrometry （UPLC-MS/MS） method was developed for the determination of 22 OPEs and their diester metabolites （mOPEs） and 11 phthalate ester metabolites （mPAEs） in whole blood. The whole blood samples were extracted with 0.1% formic acid-acetonitrile by liquid-liquid extraction for protein precipitation， and then purified by HMR S-micro BIO 96-well solid phase extraction column. The filtrate was blown to near dryness with nitrogen， and reconstituted with 0.1% formic acid-acetonitrile solution. The target compounds were detected by UPLC-MS/MS. A Ghost Trap DS-HP chromatographic column （30 mm×2.1 mm） was used as the background ghost peak trap column， and an ACQUITY UPLC^® BEH C18 chromatographic column （150 mm×2.1 mm， 1.7 μm） was used as the analytical column. Methanol and 0.5 mmol/L ammonium acetate were used as mobile phase for gradient elution. Electrospray ionization （ESI） was used for MS detection， with both positive and negative ion scanning in the multiple reaction monitoring （MRM） mode. Isotope internal standard method was used for quantification. The results showed that 33 target compounds could be separated within 15 min， and good linear relationships were observed for all target compounds across their respective mass concentration ranges （r=0.993 3-0.999 8）. The limits of detection were 0.003-0.31 ng/mL and the limits of quantification were 0.01-1.02 ng/mL. The spiked recoveries of 33 targets in whole blood samples ranged from 60.5% to 138.3%， with relative standard deviations （RSDs） from 1.6% to 11.0%. The detection rates of tris-（2-chloroisopropyl）phosphate （TCiPP）， triphenyl phosphate （TPHP）， 2-ethylhexyl diphenyl （EHDPP）， mono（2-ethyl-5-hydroxyhexyl） phthalate （MEHHP）， mono-n-butyl phthalate （MNBP） and mono-n-octyl phthalate （MOP） were 100% in 14 whole blood samples， and the highest detection amount of TPHP was 10.04 ng/mL. The developed method is simple to operate， sensitive， accurate， requires small sample volumes， and is cost-effective on reagents. It is suitable for human biomonitoring， and provides a theoretical basis for monitoring organic phosphate and phthalic ester substances in the population.

Carbonyl compounds （CCs） are a pivotal class of oxygenated volatile organic compounds in ambient air， which are mainly derived from natural emissions， primary emissions from anthropogenic sources， and secondary formation due to atmospheric oxidation. Various classes of CCs have different impacts on human health， and play critical roles in atmospheric photochemical reactions， ozone production， and the formation of secondary organic aerosols. At present， the number of CCs in ambient air determined by traditional methods is limited， especially for high molecular weight monocarbonyl compounds （HMW-MCs） and dicarbonyl compounds （DCs）. If more CCs can be accurately determined， it will be beneficial for the study of atmospheric oxidation mechanisms and the formulation of pollution control strategies.In this study， an analytical method was developed that enables simultaneous determination of the 40 CCs in ambient air with a single injection， utilizing high-performance liquid chromatography-triple quadrupole mass spectrometry. First， the 16 CCs-2，4-dinitrophenylhydrazine （DNPH）-derivatized single standards were prepared using purified DNPH crystals in the laboratory. Second， the remaining 24 commercial CCs-DNPH-derivatized hybrid standards were purchased. Finally， all the above standards were mixed in a certain proportion to prepare the 40 CCs-DNPH-derivatized hybrid standards for later use. The sample collection procedures （sampling flow rate and sampling duration）， the pretreatment methods （elution volume and constant volume）， the chromatographic analysis conditions （chromatographic column， the concentration of ammonium acetate， etc.） and the mass spectrometry analysis conditions （ion source parameters， fragmentation voltage， collision energy， etc.） were optimized. Ambient air samples were collected using DNPH cartridges （at a flow rate of 1 L/min， for 4 h）， eluted with 4 mL of acetonitrile and diluted to a final volume of 5 mL （the acetonitrile naturally flowed through the DNPH cartridges in the opposite direction to the sampling direction） in a vacuum drying chamber， and then filtered through a 0.22 μm organic filter membrane and transferred to 1.5 mL brown sample bottles prior to instrumental analysis. Chromatographic separation was performed using a Sepax BR-C18 column （250 mm×4.6 mm， 5 μm） with mobile phases consisting of 1.0 mmol/L ammonium aqueous solution and acetonitrile under gradient elution conditions. The analysis was performed at a column temperature of 50 ℃ with an injection volume of 5 μL. The target analytes were identified using negative electrospray ionization （ESI^-） and multiple reaction monitoring （MRM） modes and quantified using the external standard method. The results showed that the 40 CCs exhibited good linearities within the mass concentration range of 2.5–200 μg/L， with the determination coefficients （R²） exceeding 0.997 8. The method detection limits and method quantification limits were established within the ranges of 0.001–0.03 μg/m³ and 0.005–0.12 μg/m³， respectively. The blank spiked recoveries of the target analytes at low， middle， and high concentration levels （0.05， 0.1， and 0.2 μg） ranged from 75.2% to 119.0%， while the relative standard deviations （RSDs， n=7） ranged from 0.4% to 4.2%. This analytical method was applied to the monitoring of ambient samples in the Pearl River Delta region. Except for 2-furaldehyde and isophorone， 38 CCs were effectively detected. Among these， formaldehyde， acetaldehyde and nonanal consistently showed higher concentrations across all sampling sites. Overall， the concentrations of low molecular weight monocarbonyl compounds （LMW-MCs） were moderately higher than those of HMW-MCs， and substantially higher than those of DCs. Compared with conventional methods， this method effectively overcame the limitations in existing approaches regarding the limited variety and detection difficulties of DCs and HMW-MCs. Additionally， it also improved the chromatographic resolution of target analytes which have similar retention times and the same ion pairs. Overall， this method was simple and rapid， offering excellent sensitivity， precision， and chromatographic resolution. It was suitable for the determination of the abovementioned 40 CCs in ambient air．

Current undergraduate environmental chemistry curricula often suffer from a disconnect between sample preparation and large-scale instrumental analysis， making it difficult to cultivate students’ systematic analytical capabilities. Furthermore， the experimental content predominantly focuses on conventional water quality parameters and traditional pollutants like heavy metals， lacking training in monitoring and remediation technologies for new pollutants， which creates a significant gap with national strategic needs. To address this issue， this study designed an integrated comprehensive experiment that combines material synthesis， sample pretreatment， and large-scale instrumental analysis， targeting typical new pollutants， such as organic ultraviolet filters （OUVFs） from pharmaceuticals and personal care products. A magnetic covalent organic framework （MCOF） was synthesized via a reflux heating method. Students were guided to apply it as the sorbent in magnetic solid-phase extraction （MSPE）. Owing to its facile magnetic separation， the rapid enrichment of OUVFs was achieved within 8 min， followed by quantitative determination of seawater samples using ultra-high performance liquid chromatography-tandem mass spectrometry （UHPLC-MS/MS）. Through a three-stage teaching module encompassing “pre-class preview， in-class experiment， and post-class discussion”， the experiment emphasizes enhancing students’ independent exploration abilities in adsorbent synthesis and characterization， optimization of enrichment parameters， and data analysis. Teaching practice has shown that this design not only enabled students to deeply understand the complex sample pretreatment process and the mechanism of multi-factor synergistic effects， but also significantly enhanced their comprehensive innovation and practical abilities in solving new pollutant monitoring problems.

In analytical chemistry， separation and enrichment steps serve not only as critical stages in the analytical workflow， but also as core technologies that determine the accuracy， reliability， and applicability of analytical methods. However， in conventional experimental instruction， this step is frequently overlooked owing to time constraints and an overemphasis on instrumental techniques， leading to fragmented knowledge structures and hindering the development of integrated analytical thinking that connects theory with practice. To address this issue， this study， based on the “knowledge-ability-practice” three-dimensional integrated teaching objective， innovatively establishes a “positive-negative case-based teaching” model， using the solid-phase microextraction （SPME） of six nitrogen-containing pesticides from environmental water samples as the instructional case. By comparing fibers coated with non-polar polydimethylsiloxane （PDMS） and strongly polar polyacrylate （PA）， and employing high performance liquid chromatography with ultraviolet detection （HPLC-UV）， this study systematically investigates the matching relationship between analyte polarity and coating properties. In the positive case， the PDMS coating demonstrates superior extraction performance for weakly polar pesticides based on the “like dissolves like” principle， with a linear coefficient of determination R²≥0.993 7 and detection limits ranging from 0.019 to 0.17 μg/L. In contrast， in the negative case， the PA coating shows weaker extraction efficiency due to differences in the extraction mechanism， yielding detection limits between 0.066 to 1.069 μg/L. Based on spiked recovery tests conducted on actual river water samples from Lanzhou （recoveries： 81.5% to 117%）， a multi-dimensional evaluation system of “knowledge internalization， competency enhancement， and practical literacy” is established accordingly. Teaching feedback demonstrates that the students show a marked improvement in their understanding of the core principles， and their innovative thinking and problem-solving skills are effectively cultivated. The “contrasting-case-based” pedagogical approach effectively bridges theory and experiment while stimulating students’ investigative thinking. The study provides a replicable and scalable practical model for the reform of analytical chemistry experimental teaching， which holds significant value in cultivating high-caliber talents with rational method selection and problem-solving abilities.

This paper designs an experimental scheme to meet the undergraduate experimental teaching requirements of the Pharmaceutical Engineering major. The content focuses on the detection of bifenthrin pesticide residue in tea by QuEChERS-GC-MS. The experimental contents include sample pretreatment， single-factor screening and response surface methodology optimization of QuEChERS experimental conditions， establishment of a GC-MS analysis method， determination of bifenthrin pesticide residues in tea samples， and experimental data processing. It aims to cultivate students’ ability to comprehensively apply modern analytical techniques to solve practical problems. Through this experiment， students can master the basic principles and operational skills of GC-MS instruments and equipment， and understand the complete process of pesticide residue analysis in real samples， and recognize the importance of sample pretreatment for the analysis of trace components in complex systems. Under the QuEChERS experimental conditions screened in the single-factor experiment， the recovery rate of bifenthrin in the tea samples was 85.9%. Under the QuEChERS experimental conditions optimized by the response surface methodology， the recovery rate of bifenthrin in tea samples can reach 90.33%. Among the 38 tea samples， bifenthrin was detected in 12 samples， with the maximum detected value of 0.911 mg/kg. None of them exceeded the maximum residue limit of bifenthrin in tea stipulated in the National Food Safety Standard GB 2763-2021. This teaching design involves learning relevant content before the experiment， training operational skills during the experiment， and conducting data analysis after the experiment. It can not only stimulate students’ interest in learning， but also cultivate their rigorous scientific thinking. It enables students to proactively face problems， actively analyze them and try to solve them throughout the entire learning process.

Microfluidic technology， an emerging micro-nano technology， facilitates the precise manipulation of trace liquids via diverse microstructures. It is distinguished by its miniaturization and cost-effectiveness. Among the synthetic materials employed for microfluidic chips， polydimethylsiloxane （PDMS）， a polymer material， has emerged as the optimal choice for fabricating microfluidic chips. This preference stems from its straightforward manufacturing process， high transparency， outstanding chemical stability， and biocompatibility. Biosensors developed by integrating aptamers， which serve as specific biological receptors， into PDMS microfluidic chips are termed PDMS microfluidic aptasensors. These aptasensors capitalize on the distinctive advantages of aptamers as biological recognition elements in conjunction with microfluidic technology. Microfluidic technology transforms the interactions between biomolecules into readable signals that are readily processed and reported， thereby offering sensing methods characterized by high specificity and sensitivity. This advancement significantly propels the development of point-of-care testing （POCT） for biomarkers， enabling extensive applications in areas such as cancer screening and pathogen detection， and achieving rapid， accurate， and portable testing. The attributes of PDMS microfluidic aptasensors encompass low cost， minimal consumption， short processing time， and disposability. These features effectively curtail the consumption of samples and reagents and shorten the testing duration in the POCT realm. Moreover， optimizing microchannel designs， aptamer immobilization methods， and signal amplification strategies can further enhance the performance of PDMS microfluidic aptasensors and expand their detection range. This paper elaborately expounds on the definition and development of microfluidic technology， the application research of PDMS materials and their preparation processes in microfluidic chip manufacturing， as well as the development and processing of PDMS microfluidic aptasensors. It also enumerates the applications of optical， electrochemical， and dual-mode PDMS microfluidic aptasensors based on dual detection modes in the field of biomarker POCT， thus providing theoretical support for the future development and application of novel microfluidic aptasensors.