Objective To develop for the determination of 16 kinds of rare earth elements in plant agricultural products by micro-open graphite digestion coupled with inductively coupled plasma mass spectrometry. Methods Using the micro-open graphite digestion as the pretreatment method, the effects of acid digestion system, digestion time and matrix elements (K⁺, Na⁺, Ca²⁺, Mg²⁺, Fe²⁺, Cu²⁺, Zn²⁺, Mn²⁺) on rare earth elements were investigated. Results The results showed that adding HF to the HNO₃+HClO₄ mixed acid system facilitated complete digestion of samples and significantly improved the recovery of rare earth elements. When the concentration ratio of matrix elements to rare earth elements reached 4 orders of magnitude, there was no significant interference in the determination of rare earth elements. Under optimal conditions, the standard curves exhibited good linear relationships (r≥0.999) in the range of 0-50 μg/L, with the limits of detection was 0.001-0.006 mg/kg. The method was validated using national standard reference materials, and the determination results of each rare earth element were generally consistent with the reference values. The recoveries of spiked samples were 83.2%-110.3% and the relative standard deviations were 1.0%-10.4%. Conclusion The method features simple operation, strong anti-interference capability, and high accuracy, making it suitable for rapid determination of rare earth elements in batch plant agricultural products.

Objective To develop a method for the simultaneous determination of 18 kinds of polychlorinated biphenyls (PCBs) in pork by isotope dilution-gas chromatography-high resolution magnetic mass spectrometry. Methods The optimal conditions of the accelerated solvent extractor and fully automated clean-up apparatus were determined by optimizing the extraction rate of the target substances using an accelerated solvent extractor and a fully automated clean-up instrument combined with isotope dilution method coupled with gas chromatography-high resolution magnetic mass spectrometry. A 4-factor, 3-level orthogonal test was designed using the extraction temperature, static extraction time and the number of cycles as the main factors to investigate the effect of the accelerated solvent extractor on the extraction rate of the fat content of the samples. The effects of the accelerated solvent extractor on the extraction rate of fat content of the samples were investigated. Results The linear relationships of the indicator PCBs (PCB28, PCBB52, PCB101, PCB118, PCB138, PCB153, PCB180) was good in the range of 0.5 to 200.0 pg/µL, and the linear range of the DL-PCBs (PCB77, PCB81, PCB105, PCB114, PCB123, PCB126, PCB156, PCB157, PCB167, PCB169, PCB189) had a good linear relationship in the range of 0.10 to 40.0 pg/µL, the correlation coefficients were all above 0.999. The limits of detection were in the range of 0.001-0.004 pg/g, and the limits of quantitation were in the range of 0.004-0.012 pg/g; the accuracy and precision of the fishmeal matrix standard reference material were tested by this study, and the PCBs levels were within the range with the relative standard deviations of 1.0%-7.5%. For the determination of actual samples of pork, and the contamination levels of PCBs in 18 kinds of were 1978.9-2530.8 pg/g fat. Conclusion This study is efficient, accurate, sensitive and suitable for the determination of 18 kinds of PCBs in pork.

Objective To construct a predictive model for bacterial growth in braised chicken legs under variable temperature conditions during actual circulation. Methods Based on the one-step method of the Huang model, the growth process of foodborne Escherichia coli (E. coli) in braised chicken legs was studied. Kinetic parameters for E. coli growth and survival were determined through multiple sets of isothermal experiments, ultimately yielding a second-order model describing the relationship between instantaneous colony count, temperature, time and initial colony count. The model was validated using simulation experiments. Results A significance analysis of differences was conducted between the measured growth colony counts of E. coli strains cultured under fluctuating temperatures and the predicted colony counts obtained by the model. The test showed that P=0.926>0.05, indicated that there was no significant difference between the predicted values and the measured values. Conclusion The second-order model constructed in this study can effectively simulate E. coli growth under fluctuating temperatures and is sufficiently reliable. The model, integrated with the R programming language, allows for rapid prediction of E. coli growth under fluctuating temperature conditions, providing a rapid and effective tool for risk assessment of braised meat products in actual circulation.

Objective To establish a method for the simultaneous determination of fasciolicides and its metabolite (nitroxinil, rafoxanide, closantel, triclabendazole and ketotriclabendazole) in raw milk by QuEChERS coupled with ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Methods The raw milk samples was extracted with 3% triethylamine acetonitrile-ethyl acetate acetate solution (7:3, V:V), purified by C₁₈ adsorbent powder, and determined by UPLC-MS/MS with external standard method. The chromatographic separation was performed on an ZORBAX Eclipse Plus C₁₈ (2.1 mm×100 mm 1.8 μm) column with a mobile phase of 0.1% formic acid-acetonitrile solution, and detected under multiple reaction monitoring (MRM) mode in the positive and negative electrospray ion modes. Results The results showed that a good linear relationship was obtained in the mass concentration range of 1 to 100 μg/L for fasciolicides and its metabolite, and the correlation coefficients (r) were all greater than 0.9988, the limits of detection were 2.5 μg/kg, and the limits of quantitation were 5 μg/kg. The average recoveries of 5 kinds of compounds at the concentration levels of 10, 20 and 100 μg/kg were between 86.0% and 108.2%, and the relative standard deviation ranged from 0.81% to 5.60%. Conclusion The method is simple, rapid accurate and reliable, and is suitable for the rapid determination of the residues of fasciolicides and its metabolite in raw milk.

Objective To establish a method for determination of patulin in rice bran by ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Methods The patulin from rice bran samples were extracted with ethyl acetate, purified by a solid phase extraction cartridge, eluted with the mobile phase of 0.1% formic acid solution and acetonitrile, separated on the Luna®Omega Polar C₁₈ column (100 mm×2.1 mm, 3 μm), then analyzed in positive and negative ion mode of electrospray ionization source under multiple reaction monitoring mode, quantified by matrix matching curve external standard. Results In the range of 25.0-250.0 μg/L, the peak area of patulin was linearly correlated with the content, and the correlation coefficient (r²) was 0.9993. The limit of detection was 3.0 μg/kg, limit of quantitation was 10.0 μg/kg. Meanwhile, the average recoveries of patulin in rice bran were 86.7%-96.5% with the maximum relative standard deviations of 6.2% at the spiked concentration of 25.0, 50.0, 250.0 μg/kg. Conclusion This study establishes an efficient detection method for patulin in rice bran. This method has high precision and accuracy, and is simple to operate and has high analytical efficiency at the same time. The research results provide technical support for formulating the determination standard of patulin in rice bran and related quality control specifications.

Objective To investigate the current situation of cadmium contamination in food and explore the dietary exposure risk of cadmium in the daily diet of residents in the southeast coastal areas. Methods Random sampling was conducted in major large-scale agricultural markets, commercial supermarkets, restaurants and other places throughout the city, with common commercially available foods as the research object. A total of 1285 food samples were collected from 7 categories, including grains and their products, vegetables, aquatic animals and their products, meat products, nuts and seeds, fresh edible fungi and seasonings. Inductively coupled plasma mass spectrometry method (ICP-MS) was applied for quantitative detection of cadmium content. The single factor pollution index (P_i) and target hazard factor (THQ) were used to evaluate the quality and consumption safety of each category of samples. Results After statistical analysis, there were significant differences in cadmium content among different categories of food. In the tested samples, the total detection rate of cadmium was 54.24%, and the detection result was undetected-2.86 mg/kg. Among them, crustaceans (sea crabs, shrimp) had the highest average detection value (1.2264 mg/kg). Conclusion The dietary exposure risk assessment results of tested sample indicate THQ<1. Therefore, the cadmium contamination in this region shows a low health risk to residents.

Objective To detect and analyze the residue conditions of 57 kinds of pesticide in commercially available fruits in Handan Area from 2020 to 2024 and assess the health risks of pesticide residues for local residents. Methods Followed QuEChERS extraction, samples were analyzed using liquid chromatography-mass spectrometry and gas chromatography-mass spectrometry. Chronic dietary exposure was assessed via a Monte Carlo simulation-based risk model, whereas acute risk was determined by the acute reference dose. Results The p detection rate of pesticide types in 80 fruit samples was 28.1% with an overall item detection rate of 1.12% and overall sample detection rate of 33.8% in 80 fruit samples. Dimethoate residues exceeded national standards in 6 cherry and 3 jujube samples. Two or more pesticides were detected in 16.2% of the samples. No highly or extremely toxic pesticides were detected. The chronic dietary intake risk of dimethoate was 1.81, exceeded the safe range, while the chronic dietary intake risk of other pesticides were within acceptable limits. The hazard index value was 1.87, exceeded the safe range. Acute dietary risks for all detected pesticides were within safe ranges. Dimethoate and endosulfan were identified as higher-risk pesticides in both acute and chronic assessments. Conclusion The dietary intake risk of pesticide residues in Handan City (2020—2024) is generally within safe limits. However, there are cases of dimethoate exceeding the standard and multiple pesticides detected in the same sample. Dimethoate posed chronic dietary intake risk and the relevant authorities need to maintain ongoing attention.

Objective To establish a method for the determination of 17α-estradiol and 17β-estradiol in aquatic products by QuEChERS combined with ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Methods The sample was extracted with water-acetonitrile (2:8, V:V), purified with N-propylethylenediamine, C₁₈ and neutral alumina, blown to dryness with nitrogen, and then reconstituted with water-acetonitrile (8:2, V:V). The sample solution was analyzed using water and acetonitrile (both containing 5 mmol/L ammonia) as mobile phase, separated by C₁₈ chromatographic column, scanned and detected in multiple reaction monitoring (MRM) mode, and quantified by external standard method. Results The results showed that 17α-estradiol and 17β-estradiol showed a good linear relationship in the concentration ranges of 5 to 200 μg/L, and the correlation coefficients were 0.9998 and 0.9985, respectively. The average recoveries at three spiked concentration levels varied from 66.5% to 101.1% with relative standard deviations of 0.62% to 10.17%. The limit of detection was 0.85-0.90 μg/kg, and the limit of quantitation was 2.1-2.4 μg/kg. Conclusion This method is simple, fast, sensitive and accurate, suitable for qualitative and quantitative analysis of 17α-estradiol and 17β-estradiol in aquatic products such as fish, shrimp, crabs and shellfish.

Objective To establish an analytical method for the simultaneous determination of 8 kinds of organophosphate ester flame retardants of major meat and cereal food products by QuEChERS purification technology coupled with ultra performance liquid chromatography-tandem mass spectrometry. Methods Separation was achieved on a Agilent EC-C₁₈ column (3 mm×150 mm, 2.7 μm) with a mobile phase consisting of 0.1% formic acid aqueous solution and acetonitrile under gradient elution at a flow rate of 0.4 mL/min. Detection was performed in positive electrospray ionization (ESI+) mode with multiple reaction monitoring (MRM). Results The 8 kinds of organophosphate ester flame retardants exhibited good separation and showed excellent linearity in the range of 1.0-50.0 ng/mL, with correlation coefficients all greater than 0.99. The limits of detection and limits of quantitation were 1.0 μg/kg and 2.0 μg/kg, respectively. The recoveries of this method were 70.0%-119.6%, and the relative standard deviations were 0.2%-12.7%. Conclusion The established method is simple, rapid and highly efficient in extraction, and has been successfully applied to the analysis of organophosphate ester flame retardants in food samples (including cereals and meat products).