Gel nail polish has surged in global popularity， becoming a dominant force in the cosmetics market due to its compelling advantages. This rapid market expansion， however， is shadowed by significant and growing safety concerns related to the essential chemical agents enabling its functionality—photoinitiators （PIs）. Classified as a Category 1B CMR substance （carcinogenic， mutagenic， or toxic to reproduction） based on robust evidence of reproductive toxicity， 2，4，6-trimethylbenzoyl diphenyl phosphine oxide （TPO） has been comprehensively banned within the European Union （EU） under Regulation （EC） No 1223/2009， effective from September 1， 2025. Compounding this challenge was the conspicuous absence of validated analytical methods. Specifically， standardized， reliable， and accessible techniques for quantifying the complex spectrum of PIs in modern gel nail polish formulations were critically lacking. This included established PIs such as the now-banned TPO and its potential substitutes， all of which were embedded within the challenging， heterogeneous matrix of these formulations. This methodological gap severely hindered effective quality control during manufacturing， robust post-market surveillance by regulators， accurate consumer exposure assessment， and the essential safety evaluation of emerging replacement PIs. Consequently， there was an immediate and pressing need to develop dedicated analytical capabilities capable of monitoring both prohibited high-risk PIs and their prospective successors within this specific product category. To address the critical absence of standardized analytical methods for PIs in cosmetics， this study developed and validated a robust high performance liquid chromatography with diode array detection （HPLC-DAD） protocol. The protocol enables the simultaneous quantification of five strategically selected PIs in gel nail polish formulations. These PIs include TPO， its structural analogues ethyl （2，4，6-trimethylbenzoyl） phenylphosphinate （TPO-L）， ［bis（4-methylphenyl） phosphinyl］ （2，4，6-trimethylphenyl） methanone （TMO）， and ［phenyl（2，4，6-trimethylbenzoyl） phosphoryl］ （2，4，6-trimethylphenyl） methanone （PB-TMBPO）， as well as the α-hydroxy ketone 1-hydroxycyclohexyl phenyl ketone （HCHPK）. This target panel encompasses both the currently dominant PIs and prime TPO replacement candidates. The optimized sample preparation involved efficient extraction of target analytes from the complex gel nail polish matrix using acetonitrile under ultrasonication， eliminating the need for derivatization. Chromatographic separation was achieved on a Kromasil 100-5-C18 column （150 mm×4.6 mm， 5 μm） maintained at 30 ℃. A binary mobile phase gradient （water/acetonitrile） was delivered at 1.0 mL/min， with an injection volume of 5 μL. Selective detection leveraged dual wavelengths： 243 nm optimized for HCHPK and 375 nm for the four acylphosphine oxides. Quantitation employed external calibration curves. Method validation demonstrated exceptional performance： All five PIs exhibited baseline separation from matrix interferences. Linear calibration curves spanned 2–600 mg/L with outstanding correlation coefficients （r≥0.999 9 for each analyte）. Method sensitivity was confirmed with limits of detection （LODs） ranging from 3.6 to 45 μg/g and limits of quantitation （LOQs） from 15 to 141 μg/g. Accuracy， assessed through spiked recovery experiments at low， medium， and high concentration levels， yielded excellent results （91.6%–100.4%）. Precision， expressed as relative standard deviation （RSD， n=6）， was consistently high （0.3%–4.3%）， affirming method robustness and reliability for routine analysis. Application of the validated method to 30 commercially available gel nail polish samples revealed pervasive PI presence. Total PI content ranged from 2.95% to 9.66% （mass fraction）. Each batch contained 1 to 3 distinct PIs. None of these PIs were listed on the product labels. Critically， TPO， which has been banned in Europe， was present in 90% of the analyzed products at significant concentrations （1.42%–6.43%， mass fraction）. HCHPK was detected in 76.7% of the samples， with levels ranging from 0.83% to 4.84% （mass fraction）. TPO-L was present in 10% of the samples （6.73%–7.17%， mass fraction）， while TMO was detected at 0.25% （mass fraction） in a single sample. These findings indicate the prevalent use of prohibited substances like TPO and other PIs in the current gel nail polish market. Enhanced regulation， substitution efforts， and further safety assessments are urgently required. This study delivers a simple， specific， rapid， and economically viable HPLC-DAD method specifically tailored for the challenging gel nail polish matrix. It effectively addresses the analytical gap for monitoring key PIs， particularly during the critical transition period following the EU TPO ban. The methodology provides robust technical support for quality control laboratories （both industrial and regulatory）， facilitates compliance verification with evolving safety regulations， enables accurate risk assessment of consumer exposure， and empowers the development of safer gel nail polish formulations through reliable PI quantification. The alarming market data generated underscores the immediate necessity for regulatory action and industry innovation toward eliminating high-risk PIs like TPO.

Vitamins K₁ and K₂ are both essential fat-soluble vitamins for the human body. K₁ was once used in cosmetics for its efficacy in improving dark circles by promoting periorbital circulation. However， due to its potential to cause severe allergic reactions， it is now banned in cosmetics in China and the European Union. K₂， particularly the MK-7 form， has a similar structure to K₁ but features a different side chain. It has gained attention for its skin benefits， including soothing， antioxidant， and anti-aging properties. Although there are no reports of its use in cosmetics in China yet， it has been registered three times as a new cosmetic ingredient， indicating significant market potential. Most existing methods for detecting vitamins K₁ and K₂ focus on pharmaceuticals and dietary supplements， with few studies addressing their analysis in cosmetics， especially vitamin K₂. Given the structural similarity between the two compounds， a reliable method for their simultaneous determination in cosmetic products is needed. However， cosmetic matrices are complex and often interfere with analysis. Conventional sample preparation techniques， such as liquid-liquid extraction and solid-phase extraction， are time-consuming and labor-intensive. The QuEChERS method offers a faster， simpler， and more cost-effective alternative. In this study， we selected six common types of cosmetics—water-based liquids， emulsions， creams， gels， powders， and oils， to develop and validate a simultaneous quantification method for vitamins K₁ and K₂. A QuEChERS-based sample preparation method coupled with high performance liquid chromatography （HPLC） was developed for the simultaneous quantification of vitamins K₁ and K₂ in cosmetics. To enhance specificity and confirmation capability， a complementary method using high performance liquid chromatography-tandem mass spectrometry （HPLC-MS/MS） was also established. Samples were first pre-dispersed with saturated sodium chloride solution， extracted by n-hexane under ultrasonication， and purified using QuEChERS pretreatment technique （containing 150 mg MgSO₄， 50 mg PSA， and 25 mg C₁₈）. For HPLC analysis， separation was performed on a CAPCELL PAK C₁₈ AQ column （250 mm×4.6 mm， 5 µm） using methanol-isopropanol （80∶20， volume ratito） as the mobile phase， with detection at 270 nm. For HPLC-MS/MS confirmation， an ACQUITY UPLC BEH C₁₈ column （50 mm×2.1 mm， 1.7 µm） was employed， with methanol containing 0.05% （volume fraction） formic acid and 5 mmol/L ammonium formate as the mobile phase. Electrospray ionization in positive mode （ESI⁺） and multiple reaction monitoring （MRM） were used for detection. Both HPLC and HPLC-MS/MS methods demonstrated excellent performance for the determination of vitamins K₁ and K₂. In the HPLC method， both analytes showed good linearity over the range of 0.1–50 μg/mL （r>0.999）， with limits of detection （LOD） and quantification （LOQ） of 0.3 μg/g and 1.0 μg/g， respectively. The spiked recoveries ranged from 93.2%-104.5% with RSDs below 5%. For the HPLC-MS/MS method， linearity was observed in the range of 0.005–0.5 μg/mL （r>0.999）， with LOD and LOQ values of 0.02 μg/g and 0.05 μg/g， respectively. Recoveries in this case fell within 89.4%–108.2%， accompanied by RSDs of less than 10%. The method was successfully applied to analyze 30 cosmetic samples spanning six different matrix types. Neither vitamin K₁ nor K₂ was detected in any sample. The proposed methodology is rapid， simple， sensitive， and accurate， making it suitable for routine determination of vitamins K₁ and K₂ in diverse cosmetic products. It offers reliable technical support for quality control and regulatory compliance and demonstrates the utility of QuEChERS sample preparation for the analysis of other cosmetic ingredients.

Ethylene oxide （EO） and acetaldehyde are key components of volatile organic compounds （VOCs） emissions in the petrochemical industry. The ozone formation potential of acetaldehyde is several orders of magnitude higher than that of EO. Therefore， accurately identifying and measuring these compounds is essential for developing effective ozone control strategies. However， separating EO from acetaldehyde presents a considerable analytical challenge due to their isomeric nature and comparable volatilities. In this study， a novel analytical method based on thermal desorption-gas chromatography-mass spectrometry （TD-GC-MS） technology was developed to simultaneously collect， separate， and quantify EO and acetaldehyde. Optimization was performed on the GC column temperature program， thermal desorption temperature， and thermal desorption flow rate to achieve effective separation. Compounds were separated on a TG-624 SiIMS GC column （60 m×0.25 mm×1.4 μm） with a carrier gas flow rate of 1.2 mL/min. To separate EO from acetaldehyde， the GC column temperature was specifically optimized to enhance their differences in desorption rates from the stationary phase. The temperature was initially held at 30 ℃ for 3 min， then ramped at 5 ℃/min to 120 ℃， held for 3 min. Both full scan and selected ion monitoring modes were employed for target detection. During thermal desorption， the thermal desorption temperature was set at 180 ℃， the cold trap temperature was set at -30 ℃ for capturing desorbed targets， and the secondary desorption flow rate was set at 16 mL/min with the corresponding split ratio of 12.3. The method’s performance was evaluated under optimized experimental conditions. Within the range from 1 to 10 ng/tube， the method showed strong linearity with correlation coefficients above 0.99 for EO and acetaldehyde. Method detection limits were determined to be 0.16 ng/tube for EO and 0.21 ng/tube for acetaldehyde. Thermal desorption efficiencies for both targets exceeded 95% with samples spiked at 2 and 10 ng/tube. Recovery efficiencies spiked at 2， 5 and 10 ng/tube ranged from 80.3% to 106.8%， with relative standard deviations ranging from 4.5% to 9.2%. This method was applied to VOCs samples collected from aftertreatment exhaust streams of two petrochemical units， where different concentrations of EO and acetaldehyde were detected. This study thus established a reliable method for the simultaneous collection， identification and quantification of EO and acetaldehyde in petrochemical emission matrices. Furthermore， this method can also be used for monitoring these compounds in diverse emission sources and ambient air， thereby providing essential data to support the management and control of reactive VOCs.

In the context of an increasingly severe global public health situation， diseases caused by bacteria and viruses have become a global threat， severely impacting human health worldwide. Rapid and accurate pathogen detection is crucial for preventing infectious diseases and plays a vital role in safeguarding public health through effective preventive measures. Against this backdrop， the development of efficient， simple， low-cost and widely applicable detection methods has become a key research direction in public health. As a novel detection platform， paper-based microfluidic devices （μPADs） open new pathways for pathogen detection due to their unique design and integrated properties， showing significant potential in medical diagnostics and beyond. Their low cost and ease of use make them particularly appealing for point-of-care pathogen testing， a field in which they are gaining increasing attention. These devices are user-friendly， require no complex equipment， and are easy to transport and store. This article provides an in-depth exploration of μPADs， discussing comprehensive material design considerations for microfluidic applications. It will also examine advanced fabrication techniques and innovative detection technologies in detail. Furthermore， practical detection cases for specific pathogens such as Escherichia coli （E. coli） and norovirus will be presented to demonstrate the significant advantages of these devices in applications. As scientific research advances， μPADs are expected to play an increasingly significant role and poised to greatly enhance global public health efforts. Their inherent simplicity and affordability make them ideally suited for regions with limited access to sophisticated laboratory infrastructure. They enable convenient on-site testing， which significantly reduces both time expenditure and operational costs. Furthermore， their portability makes them suitable for deployment in disaster relief scenarios and remote fieldwork. Rapid pathogen identification is crucial for effective outbreak containment. To advance this goal， μPADs can be integrated with high-sensitivity sensors and intelligent data processing modules. Advancements in material science have facilitated the development of highly sensitive and stable paper-based substrates for diverse applications. Simultaneously， nanotechnology enables the fabrication of miniaturized components. Meanwhile， bioengineering has contributed to highly sensitive detection probes. These probes can detect pathogens even at very low concentrations. In conclusion， continuous technological advancements are positioning μPADs at the forefront of diagnostic innovation. As research and development progresses， their role in global public health is anticipated to expand considerably. This progress offers considerable promise for enhancing global disease surveillance and response capabilities. The potential is largely due to the inherent simplicity of μPADs， which makes them accessible worldwide. Their low cost， portability， and ease of operation by personnel with minimal training make them particularly advantageous in low-resource settings and provide a robust platform for rapid， on-site diagnostic testing. The modular design of these devices facilitates extensive customization and scalability. This enables them to be tailored for the detection of a broad spectrum of pathogens. The technology is also readily scalable for mass production， facilitating widespread distribution. These attributes collectively make it a versatile and indispensable tool for global health initiatives. The integration of these devices with mobile technology represents a significant leap forward， enabling real-time digital tracking and monitoring of disease outbreaks. This capability significantly enhances rapid response and epidemic containment efforts. Furthermore， the collected data can also be leveraged for broader public health surveillance and epidemiological studies. The potential of this technology to revolutionize point-of-care diagnostics is immense. μPADs can deliver accurate results within minutes， a stark contrast to the hours or days required by conventional laboratory methods. This rapid turnaround time facilitates faster clinical decision-making and intervention， ultimately leading to improved patient outcomes. Moreover， μPADs hold considerable promise for the rapid detection of novel or emerging pathogens. As research and development continue unabated， the functional capabilities of μPADs are anticipated to expand significantly. Future iterations may incorporate cutting-edge detection methodologies and advancements in nanotechnology to further enhance sensitivity and accuracy. Such enhancements will further solidify the pivotal role of μPADs in global public health surveillance and infectious disease control strategies. Ultimately， μPADs hold immense potential to save lives worldwide by enabling rapid pathogen detection and effectively curbing the transmission of infectious diseases.

Okadaic acid （OA） is a fatty acid polyether biotoxin that poses risks to human health and the ecological environment. Determining the concentrations of OA in seawater not only allows for early warnings of potential toxin accumulation in marine organisms， but also helps clarify the actual impacts of OA on marine ecosystems. However， OA exists in seawater at extremely low concentrations， and the matrix has a high salt content. Thus， adequate sample pretreatment is necessary prior to high performance liquid chromatography-tandem mass spectrometry （HPLC-MS/MS） analysis. Film-based solid-phase extraction （F-SPE） has attracted considerable attention in sample pretreatment. Unlike conventional solid-phase extraction （SPE）， which relies on large quantities of adsorbent particles， F-SPE uses a thin film， thereby addressing common issues in SPE applications such as high column pressure， column clogging， and adsorbent leakage. Currently， most such films are prepared by modifying polymer film skeletons with a certain amount of adsorbent particles. Nonetheless， these adsorbent particles have inherent limitations， including insufficient adsorption capacity or irreversible adsorption， leading to poor extraction performance for specific targets. Therefore， developing new types of films with high extraction efficiency is highly significant， as it can facilitate the wider application and popularization of this technology. Covalent organic frameworks （COFs） are porous crystalline materials with adjustable pore size， high specific surface area， and excellent stability. COF films can not only inherit the high permeability of films， but also possess strong COF adsorption capacity. In this work， a COF film （TPB-BTCA） was synthesized through the liquid-liquid interface synthesis method under mild reaction conditions， and characterized in detail. The Fourier-transform infrared （FT-IR） spectrum， X-ray diffraction （XRD） pattern， and X-ray photoelectron （XPS） spectrum verify the successful preparation of the TPB-BTCA film using a Schiff base reaction. The scanning electron microscopy （SEM） images and water contact angle testing show the prepared TPB-BTCA film is a hydrophilic heterogeneous film with specific morphologies， which is beneficial to a more thorough and rapid contact between the film and the sample solution. The nitrogen adsorption-desorption experiment demonstrates the TPB-BTCA film has a high surface area （1 261.6 m²/g） and porosity （0.6 cm³/g）， providing sufficient and easily accessible sites to adsorb these OA molecules. Subsequently， the TPB-BTCA film-based F-SPE method was used for the extraction of OA in seawater. At the same time， the influence of potential factors on the extraction efficiency was also investigated， including the sample loading volume， the pumping speed for loading， the eluent type， the volume of the eluent， the pumping speed for elution， and the salt concentration. Under the optimal conditions， the TPB-BTCA film exhibited excellent extraction performance for OA. Finally， a new method for the detection and analysis of OA was established by combining F-SPE technology with HPLC-MS/MS instrument. The developed method has a wide linear range （0.8–500.0 pg/mL） with good linearity （r=0.999 0）， low limit of detection （0.2 pg/mL） and satisfactory precision （RSDs≤6.4%， n=5）. Meanwhile， seven seawater samples were used to evaluate the feasibility of the developed method for detecting OA in actual samples. Ultra-trace amounts of OA were detected in two seawater samples with concentrations of 5.4 pg/mL and 61.8 pg/mL， respectively. Compared with the reported HPLC-MS/MS methods， the developed method only requires a single layer of film to process large-volume （100 mL） seawater samples and achieve the lowest detection limit. This may be due to the advantages of the TPB-BTCA film， such as high permeability， high porosity， and high specific surface area， which enable it to efficiently extract OA from seawater. In conclusion， this study not only provides an effective analytical method for detecting ultra-trace OA in seawater， but also demonstrates the application potential of COF films in sample pretreatment.

Aquatic food products contain interfering substances， such as fats and proteins， which affect the analysis and detection of target compounds by significantly reducing detection efficiency and contaminating detection instruments. Effectively removing interfering substances is a key step in the field of food quality testing. To reduce the influence of interfering substances in aquatic products， this study established a detection method for 54 veterinary drug residues in carp by using magnetic one-step purification combined with high performance liquid chromatography-triple quadrupole/composite linear ion trap mass spectrometry （HPLC-QTRAP-MS/MS）. The purification process uses solvothermally synthesized spherical magnetite as the magnetic material. This material is strongly magnetic and enables impurities to be efficiently separated and collected. Additionally， a metal-organic framework material with an amino-rich surface （ZIF-67） was self-assembled to serve as the purifying agent. ZIF-67 is particularly effective at removing polar impurities during the magnetic one-step purification process. Scanning electron microscopy confirmed the successful synthesis of both materials， ensuring their structural integrity and suitability for the intended application.Acetonitrile was chosen as the extraction solvent owing to its excellent solubilizing properties. Furthermore， formic acid was added to enhance the extraction efficiencies of acidic veterinary drugs. Anhydrous sodium sulfate was used to remove water from the matrix， thereby further improving the purity of the extract. The extract underwent magnetic one-step purification following centrifugation， which effectively removed interfering substances while preserving the target compounds. Chromatographic separation was achieved using the C₁₈ RRHD column （15 cm×4.6 mm， 2.7 µm）， with 5 mmol/L ammonium acetate solution （containing 0.2% formic acid） and 0.2% formic acid in methanol used as mobile phases. HPLC-QTRAP-MS/MS was then used to separate and determine the analytes， with data collected in multiple reaction monitoring （MRM） mode. The 54 veterinary drugs were quantitatively analyzed using matrix-matched standard curves， thereby ensuring accurate quantification even for complex matrices. Various parameters that affect the purification fillers were investigated to optimize the purification process. Octadecyl-bonded silica gel （C₁₈） was used as an auxiliary purification material as it is known to effectively remove non-polar impurities. Combining 60 mg of ZIF-67 with 50 mg of C₁₈ yielded the best purification results. All 54 compounds exhibited weak matrix effects after pretreatment and purification， with a value of only 18.11% recorded for the compound that exhibited the most significant matrix effect. The 54 veterinary drugs exhibited excellent linear relationships between response and concentration in the 0.5–50.0 µg/L range， with all coefficients of determination （r²） above 0.99. Detection and quantification limits of 0.5–1.0 and 1.0–2.0 µg/kg were recorded， respectively. The performance of the method was evaluated by spiking blank carp matrix samples at three concentrations （2.0， 5.0， and 20.0 µg/kg）. The recovery rates of the spiked samples ranged between 81.34% and 109.85%， and intra-day and inter-day relative standard deviations were less than 10%. The rapidity and accuracy of the developed method were assessed through comparisons with existing veterinary-drug detection methods， which revealed that the developed method is more sensitive and repeatable. Furthermore， the feasibility of the established detection method was verified by testing commercial aquatic products. No target veterinary drugs were detected in actual samples， which highlights the reliability of the developed method. In conclusion， the method developed in this study provides an effective means of monitoring veterinary drugs in carp. It meets the requirements of economy， simplicity， and efficiency while exhibiting high sensitivity and reproducibility. The developed approach represents a significant advancement in the field of aquatic food safety testing and is expected to ensure more accurate and reliable detection of veterinary drug residues.

In this study， an online solid-phase extraction-ultra performance liquid chromatography-tandem mass spectrometry （online SPE-UPLC-MS/MS） method was established to rapidly screen and determine 51 per- and polyfluoroalkyl substances （PFASs） in raw and drinking water. Ammonium formate and 24 PFAS internal standards were added to each sample. The ammonium formate concentration in the sample was 2 mmol/L after mixing， and the contents of the PFAS internal standards ranged between 2.5 and 50 ng/L. Each sample was filtered through a 0.22-μm cellulose acetate filter， and a 5-mL aliquot was injected and adsorbed using an HLB online solid-phase extraction column and rinsed with 2 mmol/L ammonium formate. Acetonitrile and 2 mmol/L aqueous ammonium formate were used as mobile phases. Separation was performed on a BEH C₁₈ chromatographic column with gradient elution. Electrospray ionization source negative ion mode and multiple reaction monitoring mode were used for detection， with quantification performed using the internal standard method. The method was validated by determining accuracies and precisions for the 51 PFASs using raw water and drinking water as matrices. Excellent linear relationships within their respective ranges were observed， with correlation coefficients （r²）>0.995. The method exhibited limits of detection （LODs， S/N=3） and quantification （LOQs， S/N=10） of 0.03–1.5 and 0.1–5.0 ng/L， respectively. The PFASs were spiked at levels of 1， 10 and 50 ng/L， with spiked recoveries of 60.2%–126.9% and 60.4%–122.6% obtained for raw- and drinking-water samples， respectively， along with corresponding relative standard deviations （RSDs， n=6） of 0.3%-17.9% and 0.4%-17.7%， respectively. The developed method was used to determine PFAS residues in raw and drinking water， with perfluoroalkyl carboxylic acids， perfluoroalkyl sulfonic acids， and perfluoroalkyl ether acids detected at relatively high rates with contents of 0.1–209.7 and 0.1–63.6 ng/L in raw water and drinking water， respectively. Compared to offline solid-phase extraction methods， the developed method requires fewer samples， is more convenient from a sample-collection perspective， and uses lower quantities of internal standards. It also analyzes rapidly and is highly sensitive and reproducible. Only 20 min was required to determine the 51 PFASs at the ng/L level， from online enrichment to detection. The developed method is suitable for the trace determination of various types of PFAS， such as perfluoroalkyl carboxylic acids， perfluoroalkyl sulfonic acids， perfluoroalkyl ether acids， fluorotelomers， and fluoroalkyl sulfonamides， in raw and drinking water， thereby effectively boosting the detection efficiency for perfluoroalkyl substances in water in a manner that has substantial practical applications value.

Per- and polyfluoroalkyl substances （PFASs） are widely utilized in various industrial applications. Their persistence in ecosystems raises significant global environmental health concerns. Numerous studies have confirmed the toxicity of PFASs to human endocrine and immune systems. The carcinogenic risks associated with PFASs exposure increasingly alarm public health authorities worldwide. As a result， regulatory policies have been implemented to restrict both the production and environmental release of PFASs. In China， the GB 5749-2022 standard establishes stringent limits for PFASs concentrations in drinking water， capping levels of perfluorooctane sulfonic acid （PFOS） at 40 ng/L and perfluorooctanoic acid （PFOA） at 80 ng/L. Effective monitoring of PFASs requires advanced analytical techniques that exhibit exceptional sensitivity. Ultra-high performance liquid chromatography-tandem mass spectrometry （UHPLC-MS/MS） has emerged as the preferred technique for detecting these substances due to its superior selectivity and low detection limits. However， complex environmental matrices necessitate optimized sample pretreatment strategies to enhance analysis accuracy. Efficient extraction methods must effectively address matrix interference while ensuring analyte enrichment. Dispersive membrane extraction （DME） presents distinct advantages for the pretreatment of PFASs； its operational simplicity is complemented by high enrichment capabilities and efficient mass transfer. The selection of extraction materials critically influences DME performance parameters. Metal-organic frameworks （MOFs） are porous materials composed of organic ligands and metal clusters， featuring tunable pores， high surface areas， and rapid mass transfer. These unique properties enable their current use in sample pretreatment for environmental analysis. This study integrates DME with UHPLC-MS/MS utilizing cationic MOF membranes， enabling simultaneous detection of eight different PFASs within seawater matrices. Optimized parameters ensure reliable quantification of trace-level contaminants throughout this process. The experimental design assessed various parameters， including types of organic solvents （methanol and acetonitrile）， ammonium acetate concentrations in the aqueous phase （0.1， 0.5， 1.0， 2.0， and 5.0 mmol/L）， as well as ion source voltages （-2 500， -3 500， and -4 500 V）， all of which influenced detection efficacy. Chromatographic separation was performed using an ACQUITY UPLC BEH C18 column （100 mm×2.1 mm， 1.7 μm）. Gradient elution combined 1 mmol/L ammonium acetate with acetonitrile for optimal results. Detection was conducted utilizing electrospray ionization （ESI） in negative ion scanning mode coupled with multiple reaction monitoring （MRM）. The results indicated that all eight PFASs could be effectively separated within a timeframe of 12 min， exhibiting favorable peak shapes and high response values. Under optimal conditions， the eight PFASs demonstrated strong linearity across their respective concentration ranges； the correlation coefficients （r²） were all not less than 0.990 7. Recoveries of PFASs at spiking levels of 10， 50， and 100 ng/L ranged from 50.4% to 116.4%， while intra-day and inter-day relative standard deviations （RSDs） varied from 1.0% to 19.2% and from 2.2% to 19.5%， respectively. The method’s limits of detection （LODs） ranged from approximately 0.07 ng/L to 0.49 ng/L， whereas the limits of quantification （LOQs） varied from around 0.22 ng/L to 1.63 ng/L. Jiaozhou Bay serves as a typical semi-enclosed bay along the Pacific coast where terrestrial runoff converges nutrients alongside diverse organic/inorganic pollutants that pose potential health risks for aquatic organisms inhabiting these waters. This method was utilized for the detection of the eight PFASs in the surface seawater of Jiaozhou Bay， and seven types were successfully identified. Among these， potassium 11-chloroeicosafluoro-3-oxaundecane-1-sulfonate （Minor F-53B） exhibited the highest detection concentration， with an average mass concentration of 17.11 ng/L. When compared to the 2018 detection results of PFASs in the surface seawater of Jiaozhou Bay， the average mass concentration of perfluorooctanoic acid （PFOA） has significantly decreased. Additionally， potassium 9-chlorohexadecafluoro-3-oxanonane-1-sulfonate （F-53B）， one of the newly emerging PFASs， was detected in the surface seawater of Jiaozhou Bay， which may be attributed to the recent shift in PFASs production. The widespread use of these new PFASs may introduce environmental risks. These risks resemble those of traditional PFASs and require urgent attention. In summary， this method is operationally straightforward， rapid， and highly sensitive； it is suitable for analyzing the eight PFASs in seawater. This approach can provide a valuable data foundation and scientific basis for research and analysis concerning PFASs in environmental water bodies.

Cow’s milk protein allergy （CMPA） has become a common public health concern and hypoallergenic formula （partially or extensively hydrolyzed formula） is considered as an alternative during infancy. Alcalase and papain are widely used in industrial production of hydrolysates， as they can modify or destroy the linear and conformational epitopes of cow’s milk allergens （CMAs）， thus leading to decreased allergenicity. However， despite considerable emphasis has been laid on the manufacturing technique and nutritional value of hypoallergenic formulas， whether there are traces of CMAs in hypoallergenic formulas， remains unknown. Consequently， the need for a quantitative method of detecting multiple CMAs at a time is rising. Traditionally， enzyme-linked immunosorbent assay （ELISA）-based methods have proved to be advantageous with a wide availability of commercial kits for CMAs detection. Moreover， polymerase chain reaction （PCR）， as one of DNA-based methods， has shown exceptional specificity and high sensitivity. However， they both may encounter false-positive results and high-throughput detection is challenging. In the past two decades， mass spectrometry （MS）-based proteomic technology has advanced， including improvements in computational capability， algorithm model， as well as mass spectrometric platforms. MS is gaining more and more attention in the field of food allergen detection， allowing multiplex allergen detection with high sensitivity， accuracy and selectivity in a single run. In this study， an analytical method was developed for the simultaneous quantitation of six CMAss （namely， α-lactalbumin， β-lactoglobulin， αS1-casein， αS2-casein， β-casein， and κ-casein） in hypoallergenic formulas using ultra-high performance liquid chromatography-tandem mass spectrometry （UHPLC-MS/MS）. Proteins of spiked hypoallergenic formula were extracted with ammonium bicarbonate and digested with trypsin. After digestion， the samples were purified with a C₁₈ spin column， and analyzed by UHPLC-MS/MS （AB SCIEX Triple Quad 6500⁺）. Separation was achieved on a Waters ACQUITY UPLC Peptide CSH C₁₈ column （150 mm×2.1 mm， 1.7 μm）. The mobile phase consisted of 0.1% formic acid aqueous solution and 0.1% formic acid in acetonitrile， and the flow rate was 0.3 mL/min. The sample injection volume was 10 μL， and the column temperature was set to 40 ℃. Mass spectrometer was operated in positive electrospray ionization （ESI⁺） mode， and multiple reaction monitoring （MRM） mode was adopted. Precursor ions and product ions of marker peptides were predicted by the Skyline software. Mass spectrometric parameters such as declustering potential （DP） and collision energy （CE） were also optimized. Afterwards， by taking allergen epitopes and mass spectrometric responses into consideration， six peptides were retained for quantitative analysis. Calibration curves were constructed with good linearity in the range of 0.05-500 mg/kg， and correlation coefficients （r²） greater than 0.99. The limits of detection （LODs） were 0.05-5.0 mg/kg， and limits of quantification （LOQs） were 0.1-10.0 mg/kg， respectively. The recoveries of the developed method in incurred hypoallergenic formulas ranged from 74.8% to 93.4%. The intraday and interday accuracies ranged from -25.09% to -6.09% and from -24.0% to -5.41%， with precisions between 1.08%-5.05% and 1.35%-4.85%， respectively. Screening of commercial hypoallergenic formula samples confirmed existence of CMAs in three partially hydrolyzed formulas （pHF） and two extensively hydrolyzed formulas （eHF）， with contents ranging from 0.48 to 27.36 mg/kg. The analytical method proposed in this study exhibited high sensitivity， high-throughput capability， and can be used to monitor traces of CMAs in hypoallergenic formulas.

Organic acids are important components of dry tobacco and significantly affect its sensory properties. Therefore， determining the organic-acid composition and content in tobacco is greatly significant for evaluating its quality. Organic acids in tobacco are classified according to volatility as either volatile， semi-volatile， or non-volatile， with semi-volatile and non-volatile organic acids typically methylated for identification purposes. However， volatile acids cannot be determined in this manner owing to their low molecular weights. Therefore， a comprehensive， efficient， and accurate method for rapidly and simultaneously determining volatile， semi-volatile， and non-volatile organic acids in tobacco needs to be established. Herein， an innovative gas-chromatography–mass-spectrometry-based （GC-MS-based） isopropyl-esterification method was developed for simultaneously determining 29 volatile， semi-volatile， and non-volatile organic acids in tobacco. The developed method provides esterified small-molecule acids of lower volatility than those obtained using classical methylation and avoids interference from byproducts obtained via the esterification reaction. Experimental conditions and GC parameters were optimized， which ultimately led to 10% sulfuric acid in isopropanol （containing 0.1 g/mL p-toluenesulfonic acid） as the esterification reagent， with the reaction performed for 3 h at 70 °C and 500 r/min. The mixture was then cooled to room temperature， 10 mL of deionized water and 2 mL of n-hexane were added， and the mixture was vortexed for 30 s （4×）， after which the supernatant was collected for analysis. The DB-FASTFAME （30 m×0.25 mm×0.25 μm） and DB-5MS （30 m×0.25 mm×0.25 μm） chromatographic columns were compared， with the former finally selected for GC-MS separation and quantitative detection. All method-validation experiments were subsequently performed under the established instrumental and derivatization conditions. The 29 organic acids exhibited good linearities within the detection range， with all correlation coefficients （r²） exceeding 0.99. All recoveries at three spiked levels ranged from 81.8% to 118.7%. The intra-day repeatabilities （RSD， n=6） ranged from 0.5% to 8.1%， and the inter-day repeatabilities （RSD， n=6） ranged from 0.9% to 8.2%. The limits of detection （S/N=3） were 0.01-49.02 μg/g， and the limits of quantification （S/N=10） were 0.03-163.41 μg/g， respectively. Comparative experimental results revealed that the developed method is highly consistent with the classical methylation-based derivatization method for the detection of semi- and non-volatile organic acids in tobacco. Furthermore， the new method is able to simultaneously determine volatile organic acids that cannot be analyzed using the classical methylation method. Therefore， the developed method is more widely applicable for determining acids in tobacco. The newly developed method was used to determine three types of tobacco sample： flue-cured tobacco， cigar tobacco， and burley tobacco， with all 29 organic acids successfully detected. Cigar tobacco leaves were found to contain significantly more volatile organic acids than flue-cured tobacco， especially 3-methylvaleric acid； they also contain less semi-volatile organic acids and more non-volatile organic acids than flue-cured tobacco. The developed method is simple， accurate， and suitable for the large-scale simultaneous determination of volatile， semi-volatile， and non-volatile organic acids in tobacco； it also provides additional technical support for the study of organic acids in tobacco and evaluating tobacco quality.