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Chinese Journal of Chromatography
2025, Vol. 43, No. 10
Online: 08 October 2025

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Simultaneous determination of 15 bisphenols in prepared dishes by soild phase extraction purification-ultra performance liquid chromatography-tandem mass spectrometry ZHAN Ziyue, ZHANG Qi, TIAN Shuangshuang, ZHAO Ziwei, DAI Yanyu, LIU Bolin 2025, 43 (10):  1089-1099.  DOI: 10.3724/SP.J.1123.2024.11014 Abstract ( 243 )   HTML ( 35 )   PDF (1312KB) ( 209 )   Supporting Information 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， and high spiked levels were 70.9%‒105.8% and 0.6%‒9.1% （n=6）， respectively. The established method was used for the analytical determination of the 15 BPs in 30 prepared dishes samples， bisphenol A， bisphenol B， bisphenol C， bisphenol G， bisphenol S and bisphenol AF were detected in 11 samples， with bisphenol A exhibiting the highest detection rate of 16.7%， followed by bisphenol C， bisphenol G， bisphenol B， bisphenol AF， and bisphenol S， with values of 10.0%， 10.0%， 6.67%， 6.67% and 3.33%， respectively. The median contents of bisphenol G， bisphenol B， bisphenol A， bisphenol C， bisphenol S， and bisphenol AF were 4.15， 3.25， 2.68， 2.16， 1.49， and 0.47 μg/kg， respectively， with two BPs detected in 16.7% of the samples. The developed method involves simple pretreatment， is highly precise and sensitive， and is capable of accurately and qualitatively analyzing the 15 BPs in prepared dishes.

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Determination of 13 janus kinase inhibitors in anti-alopecia cosmetics by ultra-high performance liquid chromatography-tandem triple quadrupole composite linear ion trap mass spectrometry FAN Leilei, CHEN Maoqin, WANG Haibo, YANG Qiuhong 2025, 43 (10):  1100-1108.  DOI: 10.3724/SP.J.1123.2025.02008 Abstract ( 98 )   HTML ( 16 )   PDF (1554KB) ( 86 )   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. Calibration curves were constructed by plotting the peak area of quantitative ions against the compound mass concentration. These curves exhibited excellent linearity within the investigated concentration range， with r all exceeding 0.996. The limits of detection （LODs） and limits of quantification （LOQs） of the 13 JAK inhibitors were 1.5–1.7 ng/g and 9.2–10.9 ng/g. To validate accuracy and precision， two cosmetic matrices （water-soluble and cream） were tested at three levels： LOQ， 2×LOQ and 10×LOQ. Recoveries of the 13 JAK inhibitors ranged from 94.7% to 102.2% for the water-soluble matrix and from 92.4% to 99.2% for the cream matrix， with relative standard deviations （RSDs） ≤8.8%. This method is characterized by high efficiency， rapidity， accuracy， sensitivity and simplicity， making it a powerful tool for rapid risk screening and simultaneous quantitative analysis of JAK inhibitors in anti-alopecia cosmetics.

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Simultaneous determination of 38 indazole amides synthetic cannabinoids and 15 metabolites in wastewater by solid phase extraction-liquid chromatography-tandem mass spectrometry YANG Zhe, JIANG Liwei, WU Yidi, JIA Rui, LYU Jianxia 2025, 43 (10):  1109-1118.  DOI: 10.3724/SP.J.1123.2024.11016 Abstract ( 123 )   HTML ( 15 )   PDF (901KB) ( 72 )   Synthetic cannabinoids （SCs）， which are significantly more potent and efficacious than natural cannabis， are among the most widely abused new psychoactive substances. The emergence of the so-called first-generation SCs was followed by other SCs that eventually led to the development of eighth-generation indole/indazole amide-based SCs. Indeed， this entire category of SCs was added to the list of controlled substances on July 1， 2021. SCs can be disguised in various ways and are commonly sold in the form of electronic cigarette oil. SCs quickly enter the bloodstream through the lungs when smoked and are eventually excreted in the forms of precursors and metabolites in urine and feces following oxidation and metabolism， and finally enter the urban sewage system. SCs abuse can be studied and evaluated by analyzing SCs and their metabolites in municipal wastewater， thereby providing a practical reference. Therefore， methods for detecting SCs and their metabolites in wastewater need to be developed.In this study， a solid phase extraction （SPE）-liquid chromatography-tandem mass spectrometry （LC-MS/MS） method was developed for the simultaneous determination of 38 indazole amide SCs and 15 metabolites in wastewater. Samples were treated using OasisⓇ MCX SPE， and multiple reaction monitoring （MRM） mode was used with mobile phases comprising （A） 0.1% formic acid aqueous solution and （B） methanol-acetonitrile （1∶1， v/v）. The following gradient-elution conditions were used： 0-8 min， 55%A-15%A； 8-15 min， 15%A； 15-16 min， 15%A-55%A； 16-18 min， 55%A. Target analytes were separated using a SHIMADZU Shim-pack GIST-HP C18 AQ column （100 mm×2.1 mm， 1.9 µm） at a column temperature of 40 ℃ and a flow rate of 0.4 mL/min. The injection volume was 10 µL. The 38 SCs and 15 metabolites were identified within 11 min using MRM mode； these analytes exhibited good linear relationships and correlation coefficients （r） exceeding 0.990 5. The limits of detection were 0.03-1.30 ng/L， and the limits of quantification were 0.11-4.30 ng/L， respectively， which meet the requirements for analyzing SCs and their metabolites in actual samples. Precisions （n=6） were determined to be 2.1%–15.5% by spiking wastewater samples with 10， 50， and 200 ng/L of the 38 SCs and 15 metabolites. Recoveries of the 38 SCs and 15 metabolites were 61.2%-129.3% by spiking wastewater samples at low （10 ng/L）， medium （50 ng/L）， and high （200 ng/L） levels. Good performance was observed when real samples were analyzed. The developed method is accurate， rapid， sensitive， and effective for the determination of the 38 SCs and 15 metabolites in wastewater， thereby satisfying monitoring and evaluation requirements.

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Rapid determination of 12 photoinitiator residues in medicinal composite membranes by ultra performance convergence chromatography-tandem mass spectrometry CAO Yunjiao, LIU Chenxi, CHEN Leilin, SHANG Yue, CHEN Xiaoli, HU Bei, FU Meng, HU Min 2025, 43 (10):  1119-1126.  DOI: 10.3724/SP.J.1123.2025.03025 Abstract ( 80 )   HTML ( 18 )   PDF (980KB) ( 64 )   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 CSHTM 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 relationships in the range of 0.1-2.0 μg/mL， with correlation coefficients （r）>0.995. The limits of detection （LODs） and quantification （LOQs） for the 12 photoinitiators were 0.03 μg/mL and 0.1 μg/mL， respectively. At 1LOQ， 2LOQ， and 10LOQ levels， the average recoveries of the 12 photoinitiators ranged from 80.7% to 119.7%， with relative standard deviations （RSDs） between 1.0% and 5.6%. Twelve batches of medicinal composite membranes were tested using this method， and six batches were found positive. The detected photoinitiators were 4-methylbenzophenone， methyl-2-benzoylbenzoate， benzophenone， and 2-isopropylthioxanthone. Among them， methyl-2-benzoylbenzoate showed the highest concentration， but it did not exceed the proposed limit. The established method is accurate， sensitive， rapid， environmentally friendly， and simple pretreatment， which is suitable for monitoring residual photoinitiators in medicinal composite membranes.

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Occurrence characterization of fluorinated liquid crystal monomers in indoor dust and human health exposure risks WANG Shiyuan, HUA Kai, HE Jiahao, GAO Ke, LU Liping 2025, 43 (10):  1127-1135.  DOI: 10.3724/SP.J.1123.2025.03021 Abstract ( 79 )   HTML ( 9 )   PDF (1471KB) ( 27 )   Supporting Information Fluorinated liquid crystal monomers （FLCMs） are the most widely used materials in liquid crystal display （LCD） manufacturing. They can be released into environmental media during production， use， and disposal， and are recognized as a class of novel persistent organic pollutants. Contamination of FLCMs in indoor dust is closely linked to human health； however， existing research has yet to fully elucidate their occurrence characteristics and population-differentiated health risks within this medium. This study analyzed the occurrence characteristics of FLCMs in dust from five indoor environments （laboratories， dormitories， classrooms， print shops， and cafeterias） using comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry （GC×GC-TOF MS）. Population-differentiated health risks were further evaluated by Monte Carlo simulation. The results showed that the total contents of 20 target FLCMs ranged from 3.68 to 593 ng/g （median： 85.1 ng/g）. Print shops exhibited the highest ∑FLCMs contents （206-593 ng/g）， followed by laboratories （89.0-219 ng/g） and classrooms （28.4–137 ng/g）. This differential distribution was closely associated with the number and types of electronic devices， ventilation conditions， and indoor cleaning frequency. The health risk assessment indicated that 4-［difluoro（3，4，5-trifluorophenoxy）methyl］-3，5-difluoro-4′-propylbiphenyl （tFPO-CF2-dF3B）， and 4-［trans-4-（trans-4-ethylcyclohexyl）cyclohexyl］-1-trifluoromethoxybenzene （2bcHtFMeOP） pose a higher health risk （hazard quotient （HQ）>1.00×10-6） than the other FLCMs， which is probably result of their higher fugitive contents as well as higher autotoxicity. Print stores had the highest hazard index （HI） for all age groups （median HI range： 1.88×10-5-1.60×10-4）， which was 2-6 times higher than other sites. Population difference analysis reveals that minors （especially infants and young children） are more sensitive to indoor dust FLCMs exposure， which may be due to the high exposure rate of infants and young children caused by their crawling， playing， and hand mouth contact on the ground. In addition， the results indicate that the estimated daily intakes （EDIs） of elderly people （>60 years old） is higher than that of the 18-45 and 45-60 age groups， which may be related to their longer indoor exposure time and lower cleaning frequency due to their limited mobility. It is worth noting that in the college environment group （18-45 years old）， although the exposure risk in this age group is lower than that of the sensitive population mentioned above， the related health risks cannot be ignored. In addition， it was found that the exposure risk of women in this group was slightly higher than that of men， which may be because women usually spend more time indoors and have a higher frequency of exposure. This study fills the gaps in the occurrence characteristics of FLCMs in indoor dust and population differentiated health risk assessment， providing comprehensive and detailed data support for the control and management of FLCMs pollution.

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Serum levels of polycyclic aromatic hydrocarbons and health risk assessment among children and adolescents WANG Lipan, DENG Zhiyong, SHI Shiyu, WANG Huawei, LIU Kang’an, LI Xiang, ZHANG Mingye, MEI Surong 2025, 43 (10):  1136-1144.  DOI: 10.3724/SP.J.1123.2025.07015 Abstract ( 74 )   HTML ( 5 )   PDF (593KB) ( 38 )   Supporting Information Polycyclic aromatic hydrocarbons （PAHs） are a class of persistent organic pollutants that are widely present in various environmental media such as air， soil， and water. They are highly environmentally stable and are mainly derived from combustion processes and industrial emissions. Although numerous studies have shown that PAHs are carcinogenic， mutagenic， and neurotoxic， their exposure levels and associated health risks in specific populations require further study. Children and adolescents are in a critical stage of growth and development， with immature physiological and immune systems， making them more sensitive to PAHs than adults. Hence， their internal exposure levels to PAHs and the associated health risks warrant particular attention. However， most of the existing studies have focused on adults， and there are relatively few studies on PAHs exposure in children and adolescents. Therefore， a total of 1 096 children and adolescents aged 6-18 years in a city located in western China were investigated. The concentrations of 12 PAHs in serum samples were simultaneously determined by solid-phase extraction coupled with gas chromatography-tandem mass spectrometry （SPE-GC-MS/MS）， and the effects of demographic characteristics， lifestyles， socioeconomic factors， and dietary habits on the concentrations of PAHs in serum were investigated using multiple linear regression models. The total estimated daily intake （TEDI） of PAHs was calculated based on their serum concentrations， and the hazard quotient （HQ） was derived using the reference dose （RfD） to evaluate non-carcinogenic health risk. Meanwhile， carcinogenic risk was evaluated based on the benzo［a］pyrene equivalent （BaPeq） concentrations. The results showed that six PAHs were detected in the serum of more than 50% of children and adolescents， in descending order， with anthracene （Ant） （87.2%）， phenanthrene （Phe） （76.3%）， fluorene （Flu） （69.3%）， acenaphthene （Acp） （62.1%）， pyrene （Pyr） （54.3%）， and acenaphthylene （AcPy） （53.7%）. Phe showed the highest median mass concentration of 3.03 ng/mL. Age was positively associated with serum concentrations of all six PAHs （AcPy： β=0.097， 95% CI： 0.033–0.160； Acp： β=0.103， 95% CI： 0.032–0.174； Ant： β=0.056， 95% CI： 0.016–0.097； Flu： β=0.085， 95% CI： 0.009–0.162； Phe： β=0.098， 95% CI： 0.029–0.167； Pyr： β=0.136， 95% CI： 0.078–0.195）； overweight and obese participants exhibited lower levels of AcPy （β=–0.538， 95% CI： –1.022– –0.053） and Acp （β=–0.566， 95% CI： –1.104– –0.028）； lower PAHs levels were also found in children and adolescents from families with higher maternal education； higher frequency of vegetable intake was positively associated with Acp （β=0.088， 95% CI： 0.012–0.165）， while higher milk intake was inversely associated with AcPy （β=–0.072， 95% CI： –0.145– –0.000）， Acp （β=–0.087， 95% CI： –0.167– –0.007） and Phe （β=–0.095， 95% CI： –0.173– –0.017）； the use of water cooler jug was positively linked to serum levels of Ant （β=0.462， 95% CI： 0.149–0.774） and Phe （β=0.898， 95% CI： 0.367–1.428）. HQ values for Pyr were all less than 1， indicating that the level of Pyr exposure in the serum is insufficient to pose a significant non-carcinogenic health risk. The carcinogenic risk assessment revealed that Ant and Phe were the major individual compounds contributing to the carcinogenic risk posed by PAHs exposure in children and adolescents， accounting for 85% of the total BaPeq concentration. In summary， exposure to PAHs is common among children and adolescents in this region. Age， body mass index （BMI）， maternal education level， and diet may be the main factors influencing serum PAHs concentrations. The overall non-carcinogenic risk among the studied population was low， and Ant and Phe were identified as the individual compounds with the greatest carcinogenic potential. These findings highlight the need for strengthened monitoring and targeted health interventions regarding long-term， low-dose PAHs exposure in children and adolescents.

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Simultaneous detection of 34 pesticide and metabolite residues in vegetables and fruits using improved QuEChERS-gas chromatography-tandem mass spectrometry with carboxylated multi-walled carbon nanotubes ZHANG Xinzhong, WANG Xuemei, CHEN Jun, ZHANG Zhen, DING Hui, DU Xinzhen, LU Xiaoquan 2025, 43 (10):  1145-1153.  DOI: 10.3724/SP.J.1123.2025.02001 Abstract ( 91 )   HTML ( 14 )   PDF (1063KB) ( 52 )   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 demonstrated low limits of detection （LODs） and quantification （LOQs）， ranging from 0.023 to 0.817 μg/kg and 0.077 to 2.696 μg/kg， respectively. At three spiked concentration levels （low， medium， and high）， the recoveries for the 34 pesticides and metabolites ranged from 78.9% to 104.5%， with relative standard deviations （RSDs） of 1.0% to 7.8%. Additionally， matrix effects were evaluated for six types of fruits and vegetables at a spiked mass concentration of 0.2 μg/mL. The results indicated significant differences in matrix effects among the sample matrices. Chives exhibited the strongest matrix effect， followed by chili peppers and celery. Bananas， grapes， and peaches were the least affected. Overall， strong matrix effects were observed in over 20% of the analyte-matrix combinations， with vegetables generally exhibiting a stronger influence than fruits. The evaluation confirmed significant differences in matrix effects for the target pesticides and metabolites across the various sample matrices. Consequently， a matrix-matched calibration method was employed for accurate quantification to correct for these effects. The developed method demonstrates high purification efficiency， accuracy， and reproducibility， rendering it highly suitable for the simultaneous determination of multiple pesticide and metabolite residues in fruits and vegetables.

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Determination of trace polychlorinated biphenyls in environmental water samples by solid-phase microextraction-gas chromatography-tandem mass spectrometry using carbon nanotube composite microspheres materials SONG Xinli, ZHU Shuqi, WU Yuxin, ZHONG Liyan, LIU Yuqing 2025, 43 (10):  1154-1161.  DOI: 10.3724/SP.J.1123.2025.01004 Abstract ( 75 )   HTML ( 9 )   PDF (1489KB) ( 22 )   Polychlorinated biphenyls （PCBs） pose serious threats to the environment and human health because they are among the most common and persistent organic pollutants globally. In this study， six PCBs were extracted from environmental water samples using multiwalled carbon nanotubes （MWCNTs） on polystyrene （PS） microspheres as the solid-phase microextraction （SPME） coating material for gas chromatography-tandem mass spectrometry （GC-MS/MS）. This coating material is highly stable and exhibited a high extraction efficiency. 2，2′，5，5′-Tetrachlorobiphenyl （PCB-52）， 2，2′，4，5，5′-pentachlorobiphenyl （PCB-101）， 2，3′，4， 4′，5-pentachlorobiphenyl （PCB-118）， 2，2′，3，4，4′，5′-hexachlorobiphenyl （PCB-138）， 2，2′，4，4′，5，5′-hexachlorobiphenyl （PCB-153） and 2，2′，3，4，4′，5，5′-heptachlorobiphenyl （PCB-180） were chosen as target analytes. The main extraction factors were optimized using a single-factor optimization method， which led to the following optimum extraction conditions： adsorption time， 50 min； agitation speed， 600 r/min； pH， 6； NaCl concentration， 1.5 mol/L； desorption temperature， 280 °C； and desorption time， 4 min. GC coupled with triple quadrupole mass spectrometry was used to quantify PCBs in water samples. The chromatographic separation system was equipped with a TG-5 SILMS column （30 m×0.25 mm×0.25 μm）， with electron impact ionization and multi-reaction monitoring modes used during mass spectrometry. Five batches of MWCNT@PS were used as SPME coating materials， which were determined to have relative standard deviations （RSD） of less than 8.8% for the six PCBs. The reusability of the MWCNT@PS coating was also investigated； RSD of the recoveries of 2.8%–9.3% were obtained after ten SPME cycles with the same coating. These results reveal that the MWCNT@PS coating materials are highly stable and reusable in SPME applications， with good results obtained under the optimal conditions. The established method exhibited linearity in the range of 0.03–1 000 ng/L for PCB-52 and PCB101， 0.07–1 000 ng/L for PCB118， PCB138， and PCB 153， and 0.10–1 000 ng/L for PCB-180， with correlation coefficients of 0.993-0.998. Limits of detection and quantification （LODs and LOQs， respectively） of 0.01–0.03 and 0.03–0.10 ng/L were determined for the developed method. The intra- and inter-day precisions exhibited RSDs of 1.64%–8.16% and 2.83%–8.41%， respectively， at 2 ng/L， 3.31%–7.19% and 3.79%–9.12%， respectively， at 10 ng/L， and 2.70%–9.38% and 4.04%–8.56%， respectively， at 100 ng/L. The established method was used to determine six PCBs in barreled drinking water， rainwater， and three environmental river water samples. No PCBs were found in barreled drinking water， rain water and river water. Satisfactory recoveries of 82.4%-113.2% were achieved at low， medium， and high levels. Accordingly， the MWCNT@PS-composite-coating-material-based SPME-GC-MS/MS method is accurate and effective. This study revealed that MWCNT@PS composites provide a good avenue for the rapid and sensitive detection of PCBs in water samples.

Technical Notes

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Quantitative determination of tetrodotoxin in poisoned biological samples by two-dimensional liquid chromatography-tandem mass spectrometry FANG Li, QIU Fengmei, WANG Yuchao 2025, 43 (10):  1162-1169.  DOI: 10.3724/SP.J.1123.2024.11026 Abstract ( 126 )   HTML ( 8 )   PDF (1082KB) ( 48 )   Tetrodotoxin （TTX） is a powerful small-molecule neurotoxin primarily produced by specific marine endosymbiotic bacteria and can be enriched during symbiosis with aquatic organisms such as pufferfish， gastropods， and blue-ringed octopuses. TTX prevents sodium ions from entering nerve cells， which affects neuromuscular conduction and leads to progressive paralysis and even death due to respiratory failure. Poisoning ascribable to the ingestion of TTX-containing seafood has occurred occasionally in some coastal areas of China. The early identification of toxins and the administration of symptomatic detoxification therapies can improve the resuscitation success rates of poisoned patients. The concentration of TTX in clinical biological samples reflects the degree of patient poisoning and their prognosis. A method was established for the determination of the TTX in poisoned biological samples by two-dimensional liquid chromatography-tandem mass spectrometry （2D-LC-MS/MS）. A human plasma or urine sample （100 μL） was accurately pipetted into a 2-mL centrifuge tube， sequentially added a 10 mg/L kasugamycin solution （10 μL； internal standard）， ultrapure water （150 μL）， and 0.5% （v/v） acetic acid in acetonitrile （250 μL） as the extraction solvent， after which the mixture was subjected to vortex mixing at 2 200 r/min for 10 min and centrifugation for 10 min at 15 000 r/min and 4 ℃. The supernatant was roughly separated using a first-dimensional reverse-phase C18 column （Hypersil Gold C18， 50 mm×2.1 mm， 1.9 μm）. The target fraction was then transferred to a hydrophilic liquid chromatography column （Acquity UPLC BEH Amide， 150 mm×3.0 mm， 1.7 μm） via a six-way switching valve for second-dimensional separation and analysis using positive electrospray ionization and selected reaction monitoring （SRM） modes. Kasugamycin served as the internal standard for TTX quantitation， using matrix-matched calibration combined with the internal standard method. TTX exhibited good linearity in the 0.2-40.0 μg/L range （equivalent to 1.0-200.0 μg/L in biological samples）， with a correlation coefficient exceeding 0.999 4. The TTX in human plasma and urine samples exhibited matrix effects of 80.9% and 98.9%， respectively， with LODs and LOQs of 0.3 and 1.0 μg/L， respectively， determined for both sample types， based on three- and ten-times signal-to-noise ratios， respectively. The TTX in human plasma and urine exhibited intra-day recoveries of 84.4%–98.4% and 84.4%–96.9%， respectively， with inter-day recoveries of 87.7%–96.2% and 84.8%–95.7%， respectively， at spiked levels of 2.0， 10.0， 50.0， and 200.0 μg/L. Intra-day relative standard deviations （RSDs） of 3.2%–7.2% and 2.9%–5.7% were recorded for TTX in human plasma and urine， respectively， with inter-day RSDs of 2.3%–3.2% and 1.0%–7.5%， respectively. The intra-day and inter-day RSDs of both sample types were determined to be lower than 7.5%. The method is accurate， fast， avoids complicated pretreatment steps， and was successfully used to detect TTX in food-poisoning scenarios.

Teaching Research

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Construction and practice of the “Construction Supports Competitions-Competitions Nurture Teaching-Teaching Promotes Learning” closed-loop innovative teaching mode： a case study of micro-plasma emission spectrometer setup and trace element analysis experiment XUE Wanyi, KE Di, ZHANG Xiao, ZHOU Xiaodong, YANG Ruining, CHAO Qingcen, CHEN Mingli, MENG Hao, YANG Ting 2025, 43 (10):  1170-1176.  DOI: 10.3724/SP.J.1123.2025.04005 Abstract ( 102 )   HTML ( 8 )   PDF (879KB) ( 44 )   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.

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Design and practice of undergraduate instrumental analysis experiment： analysis of polycyclic aromatic hydrocarbons in environmental water by solid-phase microextraction- liquid chromatography LIU Jun, WU Jiangyi, LI Jintao, CHEN Nengwang, HUANG Xiaojia 2025, 43 (10):  1177-1183.  DOI: 10.3724/SP.J.1123.2024.11024 Abstract ( 172 )   HTML ( 12 )   PDF (1167KB) ( 88 )   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.