Pesticides are ubiquitous to human life but their residues are indispensable micropollutants that threaten human health. In recent years， the global use of pesticides has increased significantly in recent years， and their environmental profiles have become increasingly complex as different generations of pesticides have appeared on the market. The residues of various legacy and emerging pesticides are omnipresent in both the environment and food medias. Consequently， developing rapid and sensitive detection technologies for analyzing multiple residues is imperative. Sample pretreatment， particularly adsorbent selection and innovation， is indispensable in this regard. So far， a wide range of hybrid nanomaterials have been used for the enrichment or adsorption of pesticide residues. While traditional solid-phase-extraction-based （SPE-based） sorbents are widely used， they lack specific interactions and are poorly selective. Normal carbon materials （e.g.， graphene oxide and carbon nanotubes）， which have large surface areas and pore volumes， have progressed significantly； however， they still have insufficient active adsorption sites. Notably， porous materials， including metal-organic frameworks （MOFs）， porous organic polymers （POPs） （including covalent organic frameworks （COFs）， covalent triazine frameworks （CTFs）， conjugated microporous polymers （CMPs）， microporous organic networks （MONs， sub-familied by CMPs， porous aromatic frameworks （PAFs）， and hyper-crosslinked polymers （HCPs））， nano-porous carbons（NPCs）， and zeolites display exceptional properties because they have high porosity， tunable pore sizes， large surface areas， and diverse modification sites. In this review， strategies for the enhancement of adsorption performance of porous-material-based adsorbents， including materials hybridization， monomer modification， configuration regulation， and properties adjustment are first introduced. Furthermore， publications from 2018 to 2024 pertaining to the utilization of porous-material-based adsorbents for diverse types of pesticides were briefly elaborated. The properties of pesticides， the designs and performance of porous materials， and their interaction mechanisms were discussed. A total of 14 types of pesticides are included in the discussion， namely organochlorine pesticides （OCPs）， organophosphorus pesticides （OPPs）， pyrethroids （PYRs）， benzoylurea insecticides （BUs）， neonicotinoid insecticides （NEOs）， phenyl-pyrazole insecticides （PPZs）， phenoxy carboxylic acid herbicides （PCAs）， triazine herbicides （TRZHs）， benzimidazole fungicides （BZDs）， azole/triazoles fungicides， strobilurin fungicides （SFs）， carbamate insecticides （Carbs）， phenyl-urea herbicides （PUHs）， and diamide insecticides. Our summary revealed that an adsorbent was predominantly designed based on the textural properties of the target pesticide and the structural characteristics of the hybrid material， such as its functional groups， polarity， and pore size， to enhance adsorption performance and selectivity. MOFs and POPs are the most commonly used pesticide adsorbents， whereas fewer NPCs have been reported in this regard. Additionally， the applications potentials of porous-material-based adsorbents were explored. The findings revealed that conventional pesticides， such as OPPs， have been significantly researched in the extraction technology field. In contrast， concerns surrounding newer pesticides， including NEOs， PPZs， and SFs， as well as some significantly detected residues （BZDs and TRZHs）， have not been fully addressed， highlighting the need for future adsorbent research that prioritizes emerging and significantly detected pesticides.

Recent years have witnessed the gradual use of dendrimers to prepare and modify various separation materials， including adsorbents and chromatographic stationary phases. Polyamide-amine （PAMAM） has become one of the most widely used dendritic materials because it is simple to prepare， inexpensive， hypotoxic， and has excellent performance characteristics. PAMAM is advantageous as a modification material for adsorbents and chromatographic stationary phases compared to other traditional materials. Firstly， the large number of terminal groups on a PAMAM dendrimer provide abundant interaction sites on the surface of the functional matrix， which is beneficial for delivering superior adsorption capacity and separation selectivity. In addition， the hyperbranched structure of a PAMAM dendrimer facilitates higher grafting efficiency on the limited surface area of the matrix while simultaneously improving the uniformity of the functional groups grafted on the surface. Moreover， the controllable structure of PAMAM dendrimer effectively regulates the surface structure of separated materials. Moreover， the terminal amino functional groups of integer-generational PAMAM dendrimer are capable of carrying a high density of positive charges following protonation or quaternization， thereby facilitating good electrostatic interactions with negatively charged anionic substances that lead to excellent enrichment and separation effects. Based on the structural characteristics of integer generation PAMAM dendrimer and the mechanism of ionic interaction， the research progress of protonated or quaternized PAMAM dendrimer in the preparation of ionic adsorbents and ion chromatography stationary phases was summarized in this paper. Their future development potential and applications prospects are also discussed.

To overcome current limitations in polar compound separation and better understand hydrophilic interaction liquid chromatography （HILIC） retention mechanisms， we designed and synthesized two novel amino acid-functionalized stationary phases using highly hydrophilic L-hydroxyproline and L-proline as modifiers through a continuous solid-liquid reaction method. The synthesized stationary phases were thoroughly characterized using Fourier-transform infrared spectroscopy （FT-IR）， thermogravimetric analysis （TGA）， and elemental analysis. Comparative elemental analysis revealed a substantial increase in carbon （C）， hydrogen （H）， and nitrogen （N） contents in both L-hydroxyproline-functionalized （L-OH-PSil） and L-proline-functionalized （L-PSil）stationary phases relative to the cyanuric chloride-bonded aminopropyl silica gel （TCT-Sil） intermediate， confirming successful functionalization. Quantitative analysis demonstrated distinct ligand densities for each phase， with L-OH-PSil exhibiting a higher loading （0.193 mmol/g） compared to L-PSil （0.178 mmol/g）. Thermal stability assessments indicated both materials maintained excellent structural integrity across a wide temperature range （20-600 ℃）， as evidenced by TGA results. To explore the chromatographic separation performance of the prepared L-OH-PSil and L-PSil stationary phases， sulfonamides were selected as solutes， and preliminary chromatographic separation investigations were conducted. The sulfonamide compounds exhibited excellent separation efficiency on both stationary phases， with retention behavior following consistent elution orders strongly correlated with analyte polarity. This observed retention pattern strongly suggested hydrophilic interactions constituted the predominant retention mechanism between the amino acid-functionalized stationary phases and sulfonamide analytes. Further supporting this conclusion， a systematic decrease in retention factors （lg k values） with increasing aqueous content in the mobile phase was observed as a characteristic feature of HILIC. Under optimized HILIC conditions， we further systematically evaluated the separation performance of both stationary phases using heterocyclic amines and nucleosides as model analytes， with direct comparison to a commercial Hypersil NH₂ column. Both custom phases exhibited exceptional column efficiency， with L-OH-PSil achieving 11 582.87 theoretical plates for 2-amino-3-methyl-9H-pyrido［2，3-b］indole （MeAαC） compared to 8 661.45 for L-PSil， while maintaining excellent performance across diverse analyte classes including plant growth hormones， flavonoids， and amines. The L-OH-PSil phase demonstrated superior chromatographic performance relative to both its L-PSil counterpart and the commercial NH₂ column. This superiority is attributable to its unique bifunctional design incorporating two hydroxyl groups， which combine the advantageous features of amino acid and diol-based stationary phases. This structural characteristic enables multiple synergistic interaction mechanisms， including π-π stacking， enhanced ion-exchange capacity， and additional hydrogen bonding sites， collectively yielding improved selectivity for polar small molecules. To further evaluate the chromatographic performance of the amino acid-based stationary phases， we investigated the effects of flow rate and column temperature using nucleosides and heterocyclic amines as model analytes. Remarkably， baseline separation was maintained even at elevated flow rates， demonstrating the robustness of both phases under high-throughput conditions. Temperature-dependent studies revealed that retention times exhibited only minor decreases or remained stable with increasing column temperature， suggesting minimal thermal effects on retention behavior. Van’t Hoff analysis yielded excellent linear correlations （r²=0.992 9-0.999 7） for all tested analytes， confirming that the retention mechanism remains unchanged across the studied temperature range while indicating an exothermic separation process. Method validation confirmed the reliability of the developed system， with chromatographic peaks maintaining excellent shape and retention time stability across varying analyte concentrations. The relative standard deviations （RSDs） of retention times for six nucleosides ranged from 0.29% to 0.59%， underscoring the outstanding operational stability and analytical reproducibility of the L-OH-PSil stationary phase. These results collectively demonstrate the robustness of the amino acid-functionalized stationary phases under varying chromatographic conditions， further supporting their potential for practical applications in polar compound analysis. These results indicate that the L-OH-PSil stationary phase has excellent potential for broad applications in pharmaceutical analysis， environmental monitoring， and bioanalytical separations.

The development of novel functional materials from renewable biomass resources has garnered widespread attention. This strategy not only effectively reduces the reliance on petrochemical raw materials in the preparation process， thereby reducing carbon emissions and mitigating environmental pollution， but also enhances their added value， promoting the development of related agriculture and forestry industries. In this study， we prepared acrylpimaric acid bonded on silica （Sil-APA） as a new stationary phase by linking the functional ligand to silica using γ-glycidoxypropyltrimethoxysilane as the silane coupling agent. The synthesized stationary phase was characterized by Fourier-transform infrared spectra （FT-IR）， elemental analysis （EA）， zeta potential analysis， and thermogravimetric analysis （TGA）. Acrylpimaric acid was successfully immobilized onto the surface of spherical silica via a ring-opening reaction involving the epoxy and carboxyl groups. Analytes and the stationary phase experience multiple interactions during the separation process owing to the coexistence of functional groups such as hydrogenated phenanthrene rings， as well as hydroxyl， carbonyl， and carboxyl groups on the surface of the Sil-APA stationary phase. Synergy involving multiple interaction mechanisms improves the separability and applicability of the Sil-APA stationary phase. We used hydrophobic， hydrophilic， and ionic compounds to probe the effects of organic-phase content， pH， and buffer-salt concentration in the mobile phase on the chromatographic performance of the Sil-APA column. The logarithm of the retention factor （log k） for alkylbenzenes in the stationary phase was found to decrease with increasing methanol content in the mobile phase during reverse-phase liquid chromatography （RPLC）； hence， the Sil-APA stationary phase exhibited typical reverse-phase retention behavior. The Sil-APA column exhibited stronger aromatic selectivity and weaker hydrophobic selectivity compared to a C18 column， which enables polycyclic aromatic hydrocarbons （PAHs） to be more-strongly retained than alkylbenzenes while also separating these hydrophobic compounds in less time. The ln k for nucleosides/bases on the stationary phase decreased with increasing water content in the mobile phase in hydrophilic interaction liquid chromatography （HILIC） mode， confirming that the Sil-APA column has typical hydrophilic retention characteristics for the separation of nucleosides/bases. Furthermore， the relationship between the pH and buffer-salt concentration of the mobile phase and ln k for nucleosides/bases reveals that hydrogen bonding and electrostatic interactions between the stationary phase and the analytes play important roles in addition to hydrophilic interactions. The ln k for ionic compounds was observed to decrease with increasing buffer-salt concentration in the mobile phase in ion-exchange chromatography （IEC） mode， while concurrently increasing with the pH of the mobile phase. These results demonstrate that the Sil-APA column exhibits classical cation-exchange behavior for the separation of cationic compounds. These multiple retention mechanisms render the Sil-APA column suitable for mixed-mode liquid chromatography （MMC）. The Sil-APA column exhibits good separation selectivity for different analyte components， further demonstrating its mixed-mode chromatographic performance and potential for complex sample analysis. Furthermore， Sil-APA demonstrated excellent chromatographic repeatability， stability， and reproducibility， as evidenced by low retention-time relative standard deviations （RSDs） of 0.076%–0.356% （n=10）， 0.05%–0.193% （n=5）， and 0.498%–2.806% （n=4） for inter-day， inter-day， and batch-to-batch precisions， respectively. In summary， we designed and prepared an acrylic-acid-modified silica stationary phase material for use in liquid-chromatography applications. The excellent separation performance observed under mixed-mode conditions demonstrates that acrylpimaric acid can possibly be used a functional stationary-phase monomer， thereby potentially broadening the applications scope of resin acids in separation science. The facile preparation of Sil-APA and its promising applications scope may also provide new concepts for the development of stationary-phase materials based on natural-product-modified silica in the liquid-chromatography field.

Per- and polyfluoroalkyl substances （PFASs） are a large group of synthetic chemicals that have been widely used in various industrial and commercial products owing to their unique physicochemical properties. However， accumulating evidence suggests that PFASs are persistent， transmissive over long distances， bioaccumulative， and toxic； consequently， their adverse effects on ecosystems and humans is of widespread concern. Serum is the most commonly used human matrix for assessing internal exposure to environmental pollutants， and several analytical methods have been developed to measure PFASs in sera. Current methods are generally fast， convenient， and robust； however， their pretreatment steps require large amounts of organic solvents and materials， such as solid-phase extraction cartridges and/or sorbents. In this study， a novel and low-cost analytical method based on cold-induced phase separation （CIPS） strategy was developed for the simultaneous determination of 31 legacy and emerging PFASs in serum. The core mechanism and distinctive feature of CIPS involves cooling an acetonitrile-water （ACN-water） mixture at a low temperature to produce two clear-cut layers： one with a high ACN proportion （the ACN layer） and an aqueous layer （water layer）. Certain chemicals are significantly enriched in the ACN layer during cooling； at the same time， impurities， especially water-soluble impurities， remain in the aqueous layer. CIPS only requires the temperature to be varied， and no external impurities are introduced during pretreatment， which dramatically reduces material costs and avoids new impurities from intervening. Our method involves the following procedure： serum was drawn accurately （0.2 mL） into a 1.5 mL Eppendorf （EP） tube， 2 ng of each isotopically labeled internal standard was added， the mixture is vortexed， and 350 µL of ACN was added， followed by vortexing and ultrasonic extraction. Subsequently， 450 µL of water is added to adjust the volume proportion of ACN to 35% （the volume percentage of ACN in the total solution）. The protein at the bottom of the tube was collected following centrifugation at 15 000 r/min for 10 min， and the supernatant was transferred to a 1 mL syringe. The syringe was frozen in a -20 ℃ refrigerator for 1 h to obtain the two layers， after which the upper layer （approximately 80–100 μL） containing ACN and the target compounds was finally transferred to a glass vial for instrumental analysis. Liquid chromatography coupled with triple quadrupole mass spectrometry augmented with electrospray ionization （LC-ESI-MS/MS） was used to quantify the PFASs. The analytes were separated using a C18 column， with methanol and 2 mmol/L of ammonium formate-H₂O used as mobile phases. Linearities， limits of detection （LODs） and， limits of quantification （LOQs）， recoveries， precisions， and matrix effects were determined under the optimal conditions. The LODs and LOQs of PFASs in serum were 0.01–25 and 0.03–83 pg/mL， respectively. Under two spiked levels， namely 5 ng/mL and 25 ng/mL， average recoveries ranged between 60.5% and 129.6%， with relative standard deviations （RSDs） of less than 22.8%. Under 5 pg/mL as LOD spiked level， average recoveries ranged between 61.6% and 199.1%，with RSDs<29.4%. While matrix-effect testing revealed slightly enhanced signals， the use of isotopically labeled internal standards compensated for these effects. Real samples were subsequently analyzed， with 50 human serum samples collected in first trimester of pregnancy women living in the Shunyi District， Beijing. Nine PFASs exhibited high detection frequencies （>80%）， which suggests that PFASs are ubiquitous in the population. The median and mean levels of Σ₃₁PFASs （sum of 31 PFASs） in serum were 21.8 and 22.9 ng/mL， respectively， and the range was 0.456-73.9 ng/mL. Both legacy and emerging PFASs were detected at high frequencies and contamination levels， which suggests that they are widely used. In summary， the method developed in this study is fast， sensitive， and solvent- and material-efficient； it is also very linear and highly accurate， and exhibits satisfactory extraction recovery and enrichment factors； hence， it is suitable for surveying large populations as well as for use in environmental epidemiology.

China is the world’s largest producer and consumer of aquatic products. Insecticides， as well as veterinary drugs， such as quinolones， macrolides， nitroimidazoles， sulfonamides， and amphenicols， are widely used in aquaculture. These compounds play crucial roles in preventing， controlling， and treating diseases in aquatic organisms， improving feed conversion rates， and promoting the healthy growth of farmed species. However， the illegal use of veterinary drugs， their overuse， and noncompliance with drug withdrawal periods by farmers can lead to aquatic products containing veterinary drug residues. This study focused on fish， shrimp， and crabs with the aim of meeting the green-development needs of China’s aquaculture industry， strengthening risk warnings and preventing veterinary drug residues in aquatic products， enhancing the quality and competitiveness of farmed aquatic products， and promoting the sustainable development of the aquaculture industry. Instrumental working conditions were optimized， and the extraction solvent， extraction method， purification materials， and the redissolution solvent used in the sample-pretreatment process were determined. These efforts led to the establishment of a protocol for the detection of 50 veterinary drug residues， including quinolones， macrolides， nitroimidazoles， sulfonamides， amphenicols， and insecticides， in fish， shrimp， and crabs， which involved one-step pretreatment with a composite purification column in combination with ultra-performance liquid chromatography-tandem mass spectrometry （UPLC-MS/MS）. A 5-g sample was extracted with a 1.0% acetic acid solution， dehydrated with anhydrous sodium sulfate， and purified using a FAVEX purification column， after which the purified solution was nitrogen-blown to near dryness. The residue was re-dissolved in 1.0 mL of 0.2% formic acid aqueous solution-methanol （9∶1， v/v） ， filtered， and then separated using a Waters ACQUITY UPLC^® BEH C18 column （100 mm × 2.1 mm， 1.7 μm）. Data were collected in positive- and negative-ion multiple reaction monitoring modes， and quantified using isotopic internal and external standards. All target compounds exhibited good linear relationships within their respective concentration ranges， with coefficients of determination （R²） greater than 0.990 0. Average recovery rates of 60.1%–117.8% were determined for the 50 veterinary drugs in the fish matrix， with RSDs of between 1.89% and 15.0%， while the shrimp matrix delivered average recovery rates of 60.2%–119.7%， with RSDs of 1.11%–15.6%， and the crab matrix exhibited average values of 60.7%–119.7% and 2.94%–15.0%， respectively. The developed method is advantageous owing to its simple pretreatment step， high throughput， low organic-solvent consumption， good accuracy， high sensitivity， and cost-effectiveness. One hundred and fifty batches of aquatic products， including 50 batches of fish， 50 batches of shrimp， and 50 batches of crab， were risk-screened for 50 veterinary drug residues using the established detection method. Veterinary drug residues were detected at a rate of 47.3%， with an over-standard rate of 7.3%. Specifically， the fish samples exhibited a detection rate of 66.0%， with contamination concentrations of 1.20–257.1 μg/kg. In contrast， the shrimp samples exhibited a detection rate of 18.0%， with contamination concentrations of 1.10–8.60 μg/kg， while values of 22.0% and 3.00–7.30 μg/kg， respectively， were determined for the crab samples. This study identified a total of seven veterinary drug residues， namely pefloxacin， norfloxacin， ciprofloxacin， enrofloxacin， sarafloxacin， sulfadimethoxine， and sulfamethoxazole， with detection rates of 0.67%， 5.3%， 12.7%， 20.7%， 4.6%， 2.00%， and 1.33%， respectively. The detection method established in this study provides strong technical support for monitoring and assessing aquatic-product risks in a timely manner， and is expected play an important role in ensuring food safety， protecting consumer health， and promoting the healthy development of the aquatic-product industry.

Statistical evidence indicates that individuals spend approximately 90% of their time indoors on a daily basis. A multitude of human activities， including incense burning， cooking， smoking， and the use of electrical appliances， can contribute to indoor air pollution. This phenomenon poses a significant risk of indoor exposure to human health risks. Incense burning， as one of the major indoor pollution sources， has been increasing in use in recent years due to its special effects in religious practices and regional lifestyles. Incense usually consists of herbs， wood powder， bamboo sticks， scented materials， and binder powders， and the specific chemical composition of each type of material is complex due to different uses and manufacturing processes； and the degree of complete combustion， thermal degradation and volatilization processes of different types of incense vary greatly， resulting in the release of gaseous and particulate organic compounds whose compositions are not yet clear. Studies have shown that the emission factors of particulate matter released from incense burning may be much higher than those produced during the combustion of charcoal， wood and cigarettes. The levels of organic pollutants emitted by incense burning， such as aromatic hydrocarbons， esters， ketones， benzenes， and phenols， are much higher than outdoor levels. Prolonged exposure to incense smoke has been shown to cause respiratory damage and potential genotoxicity. Therefore， accurate identification and measurement of the organic pollutants emitted from incense burning is particularly important to accurately assess their environmental and population health risks. Herein， this study established an analytical method based on ultrasonic extraction-gas chromatography-mass spectrometry （GC-MS） for the simultaneous determination of 67 organic compounds in gaseous and particulate emissions from incense burning. These compounds include 29 esters， seven benzene series， 14 phenols， and 17 polycyclic aromatic hydrocarbons （PAHs）. Particulate and gaseous components released during indoor incense burning were collected using quartz filter membrane and self-made XAD-2 resin sampling tubes， respectively. Non-targeted analysis of incense components was performed using a GC-quadrupole-Orbitrap high-resolution mass spectrometry （GC-Q-Orbitrap-HRMS） to achieve preliminary identification of trace organic compounds in the incense-burning samples. Subsequently， targeted analysis was conducted using GC-MS in selected ion monitoring （SIM） mode， with quantification performed using the external standard method. Method validation results demonstrated good linearity for all 67 organic compounds within the range of 10 to 500 μg/L， with correlation coefficients （r）≥0.999 0. The limits of detection （LODs） and quantification （LOQs） were ranged from 0.02 to 0.33 µg/m³ and 0.03 to 0.67 µg/m³， respectively. At low， medium， and high spiked levels， the recoveries for the 67 organic compounds in the gaseous phase ranged from 72.7% to 119.0%， with relative standard deviations （RSDs） of 0.9% to 4.1%； for the particulate phase， the recoveries for the 67 organic compounds ranged from 71.5% to 118.9%， with RSDs of 0.7% to 9.5%. The established method was applied to the determination of indoor incense-burning samples （incense sticks and electrically heated incense powder）， and the influence of different incineration methods on the types and contents of products was analyzed. The results indicated that during the same burning duration （30 min）， the total content of gaseous and particulate organic compounds released from ignited incense sticks was higher than that from electrically heated powdered incense. The particulate organic compounds produced by the ignited incense sticks are mainly phenolics and PAHs， followed by esters， and benzene series. The composition of particulate organic compounds from electrically heated powdered incense was similar to that of incense sticks. A large amount of benzene series were detected in the gaseous organic compounds released by burning incense sticks， and the content was much higher than that of the other three types of organic compounds. The gaseous organic compounds released by electrically heated incense powder are mainly benzene series and phenols， followed by PAHs and esters. Compared with the previously reported related monitoring methods， this method is simpler and more efficient， providing a more convenient technical means for the sensitive screening of gaseous and particulate organic compounds released by incense burning.

Volatile flavor compounds play vital roles when evaluating the flavor and quality of tobacco products. Pretreatment is always required owing to the wide range of flavor compounds and the complexity of the tobacco matrix. Solvent extraction （SE）， steam distillation （SD）， simultaneous distillation extraction （SDE）， supercritical fluid extraction （SFE）， and solid phase microextraction （SPME） are methods commonly used to extract and purify volatile flavor compounds. Among these methods， SPME coupled with headspace （HS） sampling has gained considerable attention in a variety of research fields because it combines sampling， extraction， concentration， and sample injection into a single procedure to deliver advantages that include convenient and simple sample preparation， small sample volumes， high sensitivities， and convenient operation.In this study， HS-SPME coupled with gas chromatography-mass spectrometry （GC-MS） was used to analyze the volatile aroma components in tobacco leaves. First， extraction efficiency was optimized by carefully evaluating multiple parameters， including types of solid phase microextraction fibers， extraction temperature， adsorption time， and desorption time. The number of chromatographic peaks， total chromatographic peak area， number of identified compounds， and internal-standard peak areas were used as indices. The optimized protocol involves incubating tobacco powder （1.0 g） under 80 ℃， extraction with an 80 μm divinylbenzene/carboxen/polydimethylsiloxane （DVB/CWR/PDMS） SPME needle for 30 min， followed by desorption from the fiber for a sufficient time （8 min）. These conditions led to a 1.6% RSD for the internal-standard peak area across five replicate experiments； hence， the developed method is highly repeatable. The volatile aroma components in tobacco leaves obtained from five different production areas were analyzed using the optimized parameters. A total of 107 volatile aroma compounds were identified， among which ketones， aromatics， and heterocyclic compounds accounted for more than 70% of the total volatile aroma components （excluding neophytadiene）. Tobacco leaves obtained from the Shangluo region contained the highest amount of total volatile aroma compounds， followed by leaves from Ankang， Hanzhong， Baoji， and Yan’an regions. Orthogonal partial least squares-discriminant analysis （OPLS-DA） was used to determine the main differential components from the various production regions， which identified 14 differential compounds （primarily ketones and alcohols）. This study provides a theoretical basis and reference for further exploring key volatile flavor compounds in leaves sourced from different production areas， as well as for identifying flavor-indicator substances and improving the quality of tobacco leaves.

A rapid screening method for 125 pesticide residues of different polarities in tea substitutes matrix was developed using rapid screening combined with gas chromatography-tandem mass spectrometry （GC-MS/MS）. The targets were separated on DB-1701MS quartz capillary column （30 m×0.25 mm×0.25 μm） with programmed temperature rise， detected by GC-MS/MS in multiple reaction monitoring （MRM） mode， and quantified by matrix-matched solution internal standard method. The methodological validation of 125 representative pesticides in tea substitutes was carried out by GC-MS/MS method. The results showed that the tea samples could be extracted most efficiently when using acetonitrile without immersion in water. The M-PFC TD-1 column had a good purification effect on the Dendrobium officinale flower extract with a guaranteed high recovery. The results of optimized analysis showed that the 125 components had a good linear correlation in the range of 0.01 mg/L to 1.0 mg/L （R²>0.980）. The LODs and LOQs were 0.003-0.02 mg/kg （S/N=3） and 0.01-0.05 mg/kg （S/N=10），respectively. The recoveries of the 125 targets at three levels were in the range of 62.6%-107.6% with relative standard deviations （RSDs， n=6） of 1.0%-13.8%. Compared with other classical pretreatment methods， this method does not require activation， equilibration and elution steps， consumes less solvent， and the M-PFC TD-1 column shows better purification effect， which can directly adsorb large molecular interferences， such as pigments and alkaloids， in the matrix of the substitute tea， and is easy to operate， rapid， and with high sensitivity， which is suitable for the rapid screening of pesticide multicomponent residues in the bulk substitute tea. The method established in this study was used to monitor 50 samples of tea substitutes provided by the pilot production enterprises in Guizhou Province， in which at least one pesticide residue was detected in two samples of tea substitutes， with a detection rate of 4%. This study aims to enhance the scientific and practical aspects of setting local standard indicators or technical requirements by understanding the types and levels of pesticide residues in substitute tea products.

The quality and safety of edible oils have frequently been compromised in recent years， seriously threatening consumer’s legitimate rights and health. Hence， establishing methods for determining the quality of edible oils based on their endogenous components is greatly significant. Squalene is widely present in various oils； hence， studying the thermal stability of squalene in edible oils is expected to provide a new storage-management model and a method for rapidly determining oil quality. A method for determining squalene and oxidized squalene in edible oils was established based on QuEChERS-gas chromatography-tandem mass spectrometry. Edible oil samples were extracted by n-hexane and purified using a mixed adsorbent consisting of ethylenediamine-n-propyl silanized silica gel （PSA） and silica gel （CNW BOND Si）. Separation was used a TG-5ms column （30 m×0.25 mm×0.25 μm） and the squalene was used as an internal standard for quantitative analysis in selective reaction monitoring （SRM） mode. The chromatography column and adsorbent were judiciously optimized. Methodological verification revealed good linear relationships for squalene and oxidized squalene in the ranges of 0.03–0.4 and 0.29–3.80 mg/L， respectively， with correlation coefficients （r）≥0.992 under the optimized experimental conditions. Limits of detection （LODs， S/N=3） of 0.4 and 4.0 mg/kg were obtained for squalene and oxidized squalene， respectively， with corresponding limits of quantification （LOQs， S/N=10） of 1.2 and 12 mg/kg， respectively. Spiked recovery experiments were conducted at low， medium， and high spiked levels using three different oils， the average recoveries of squalene and oxidized squalene were 81.9%‒102.5% and 89.4%‒116.1%， respectively， with relative standard deviations （RSDs， n=6） of 3.5%‒6.8% and 3.2%‒7.4%， respectively. The developed method has the advantages of operational simplicity， stability， reliability， low LODs， and is suitable for detecting squalene and oxidized squalene in edible oils. The developed method was used to evaluate the thermal stability of squalene in peanut oil. The results showed that when the temperature was lower than 120 ℃， squalene did not undergo the phenomenon of conversion to oxidized squalene. However， when the temperature exceeds 120 ℃， the peak area of squalene shows a cliff-like decline， and the formation of oxidized squalene can be clearly detected. This method was used to test rapeseed oil， peanut oil， soybean oil and corn oil. The results showed that squalene was detected in all samples， while oxidized squalene was not detected in any samples. This method aims to provide new ideas for the storage management and rapid quality identification of edible oil.

Chromatography experiments form an important component of an Instrumental Analysis Laboratory Course. In order to meet the demands of cultivating innovative talents with scientific thinking skills for the evolving educational objectives， the Instrumental Analysis Laboratory Course in the College of Chemistry and Molecular Engineering at Peking University has been reformed since 2017， with a focus on chromatography experiment teaching as a pilot project. A series of well-designed reform measures， including strengthening the design of the experimental content， focusing on the analysis of actual samples， increasing student participation， enhancing their freedom of exploration and the division of labor and cooperation， and adopting a teaching form with both virtual and real components， have been introduced. These measures have effectively stimulated students’ subjective learning initiatives， improved their understanding of the principles of instrumental analysis and the structures and functions of instruments， cultivated their abilities to comprehend， analyze， and solve problems， and strengthened their scientific thinking and literacy. Overall， the developed program has powerfully contributed to realizing the core goal of cultivating innovative talents.

Preparative chromatography plays an important separation and purification role in the pharmaceutical， chemical， and food industries. New preparative chromatography equipment that integrates automatic sampling and fraction-collecting functions was developed to improve separation efficiency and ease of use， and to meet the separation-efficiency and collection-accuracy needs of modern industry.The design concept and working principles of the device are introduced in detail. The developed equipment significantly improves the injection rate and reduces human operating errors through advanced automation technology， leading to an experimental process that is entirely more scientific and efficient. At the same time， the fraction-collection system was optimized such that it can flexibly adjust to various application requirements， thereby ensuring the highest purities and recoveries of the collected target ingredients. This innovative equipment uses a high-speed servo motor to independently drive the X-， Y-， and Z-axes of the instrument tray in order to realize high-speed sampling and collection actions at any position within the scope of the set tray， while synchronously sampling and collecting. A control circuit was used to calibrate the sampling and collection positions to ensure accuracy and that the device is compatible with a variety of sample-tray specifications to meet the preparation requirements of a wide 1–200 mL/min flow range. The developed equipment was used to separate and purify samples of stevioside and rebaudioside A， and exhibited excellent performance， including fast separation， stable output， and accurate collection. The equipment is capable of realizing synchronous sample-collection functions， thereby providing a stable and reliable separation and purification option for a wide range of industries.