Objective To establish a highly sensitive analytical method for the determination of advantame in alcoholic beverages by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Methods The wine samples were diluted 10 times with ultrapure water, filtered through a membrane, and then injected. A Kinetex^® Biphenyl 100 Å chromatographic column (100 mm×3.0 mm, 2.6 μm) was used, with water and methanol as the mobile phase for gradient elution and separation. An electrospray ionization source (ESI) was adopted for detection in the positive ion scan multiple reaction monitoring (+MRM) mode, and external standard method was used for quantification. Results Advantame exhibited an excellent linear relationship within the mass concentration range of 0.03 to 40.00 μg/L, with a correlation coefficient of 0.9999. The limit of detection was 0.10 μg/kg, the limit of quantification was 0.30 μg/kg. The average recoveries at the 4 different spiked levels of low, medium-low, medium-high and high were 80.8% to 109.8%, and the relative standard deviation was 2.7% to 12.5% (n=6). Conclusion This method has high detection sensitivity, is simple to operate, accurate and reliable, and can be used for the trace analysis and risk assessment of advantame in alcoholic foods, providing strong technical support for scientific supervision of the alcoholic beverage market.

Objective To establish a method for the determination of the migration of 9,9-bis(methoxymethyl)fluorene in plastic food contact materials and articles by gas chromatography-mass spectrometry. Methods The water-based food simulants were extracted by n-hexane, and the chemical alternative solvents (95% ethanol and isooctane) were directly injected, and the olive oil simulants were extracted with acetonitrile and then injected, and the samples were analyzed by gas chromatography-tandem mass spectrometry and quantified by external standard method. Results A method for the determination of 9,9-bis(methoxymethyl)fluorene in plastic food contact materials was established. The limit of detection was 0.01 mg/kg or mg/L, the limit of quantification was 0.03 mg/kg or mg/L, the recovery rates were 80.0%-110.0%, and the relative standard deviations were 1.2%-6.0% (n=6). The actual samples of 10 kinds of polypropylene (PP) food contact materials were determined by this method, and the detection rate was 10%, and the detection concentration was 0.12 mg/kg. Conclusion The method is sensitive, has high recovery and accuracy, and the limit of detection can meet the requirements of regulations, and can be used for the practical testing of the migration of 9,9-bis(methoxymethyl)fluorene in polypropylene (PP) food contact materials.

Objective To establish a method for the determination of fluoride ion in tea and tea beverages by activated carbon purification-ion chromatography, and then to study the health risks of tea water and tea beverages. Methods The experiment was carried out by brewing 6 kinds of tea in 2 ways respectively. Method 1: Tea was brewed in a time gradient. Method 2: Add tea once, brew tea with several times and then collect tea. Collect tea by brewing tea with water several times. The tea and tea beverages were purified by activated carbon, filtered by 0.45 μm microporous filter membrane, separated by AS23 ion chromatographic column (4.0 mm×250 mm) with 4.5 mmol/L Na₂CO₃ and 0.8 mmol/L NaHCO₃ solution as leach solution, and tested by ion chromatography. The health risk was assessed by the highest tea fluoride dissolution with method 1, the total tea fluoride dissolution with method 2 and tea fluoride content in tea beverages. Results Under the optimal analysis conditions, the limit of detection of fluoride ions was 0.016 mg/L. In the range of 0.1-5.0 mg/L, the linear relationship was good, the correlation coefficient (r²) was 0.9996, the recovery rates were 94.93%-105.32%, the relative standard deviations were 1.02%-2.13% (n=6). The method detected the amount of fluoride ion dissolved in tea, and found that the dissolution increased continuously with the extension of brewing time and reached the highest value. With the increase of brewing times, the dissolution of fluoride ion in tea increased first, and then the decline trend gradually slowed down. The dissolution rate of fluoride ion in the first 2 brewing times reached more than 65% of total dissolution. Conclusion The method has high sensitivity, good accuracy, simple operation and practical value. Daily intake of tea fluoride in tea and tea beverages obtained from 6 kinds of tea under 2 brewing methods are in line with the daily intake limit of fluoride recommended by China and the World Health Organization. The target hazard quotient (THQ) values are less than 1, and there is no significant health risk to human. It is recommended to reduce tea brewing time, wash tea, and choose high-quality tea to drink tea scientifically and healthily.

Objective To explore the types and contents of amino acids in Asparagus from different sources. Methods Post-column ninhydrin-derived photometry was established to determine the species and contents of amino acids in Guangxi, Neijiang and southwest winter, and performed data analysis using stoichiometry. Results The average amino acid content in Neijiang was 3.06%, 3.53% in Guangxi, and 5.73% in southwest China. The amino acid composition and content in Neijiang and Guangxi were similar, and the content was uniform among different batches, the amino acid content in southwest and southwest was quite different from the first two sources, and the different batches were quite different. Conclusion This research provides scientific reference for quality evaluation of Asparagus and the study of its authenticity.

Objective To synthesize a Au-Pt bimetallic nanozymes (Au-PtNFs) with oxidase and peroxidase dual-enzyme activity, and apply them in detection of organophosphorus pesticide. Methods The 3 kinds of Au-PtNFs were prepared through seed-mediated method by adjusting the amount of chloroplatinic acid, and their enzyme activities were determined using 3,3’,5,5’-tetramethylbenzidine (TMB) as the substrate. The nanozyme exhibiting the highest enzyme activity was selected and combined with the catalytic effect of acetylcholinesterase to establish a detection method for organophosphorus pesticide. Results The 3 kinds of prepared nanozymes all had flower-like structures, and the particle size enhanced with the increasement of chloroplatinic acid concentration. Steady-state dynamic experiments showed that all bimetallic nanozymes had dual-enzyme activity, and the best enzyme activity was obtained when the concentration of chloroplatinic acid was 5 mmol/L. Absorption at 620 nm exhibited a good linear correlation with the logarithm of chlorpyrifos concentration in the range of 40-90 nmol/L, and the limit of detection was 1.00 nmol/L. The method demonstrated excellent specificity and anti-interference ability, and achieved great recovery rate in real samples. Color value analysis software was used for the detection of chlorpyrifos based on smartphone. The linear range was 30-100 nmol/L and the limit of detection was 1.06 nmol/L. Conclusion The prepared Au-PtNFs exhibiting dual-enzyme activity are effectively utilized for detection of organophosphorus pesticides, which offers a novel perspective for visual detection of organophosphorus pesticides in fruits and vegetables.

Objective To develop a rapid method for detecting Salmonella, Escherichia coli O157, Listeria monocytogenes, Staphylococcus aureus, and Vibrio parahaemolyticus using multiplex polymerase chain reaction (PCR) and capillary electrophoresis technology. Methods Specific multiplex PCR primers were designed using conserved pathogenic genes of 5 kinds of foodborne pathogens, and the products were analyzed using capillary electrophoresis imaging. By optimizing the PCR reaction and electrophoresis conditions, a multiplex PCR capillary electrophoresis detection method was established. The specificity and sensitivity were studied as well. Results The specificity of the 5 pairs of primers was acceptable and no non-specific amplification occurred. The optimal primer concentration for multiplex PCR reaction was 0.2 μmol/L, and the optimal annealing temperature was 56.0 ℃. The optimal separation mode for capillary electrophoresis was AM900. The method had a high sensitivity, and the detection sensitivity could reach 5×10^-3 ng/μL. Conclusion The multiplex PCR capillary electrophoresis method for detecting 5 kinds of foodborne pathogens established in this study is simple for operation with high specificity and sensitivity, and can be very practical in detection of foodborne pathogens.

Objective To analyze the changes in microbial content of fresh cut Citrullus lanatus of different varieties over time under normal temperature and refrigeration storage conditions. Methods The 30 batches of 420 samples of the more popular of Kirin, Sweet King, and Black Beauty Citrullus lanatus, were selected as the research objects. After being divided and stored at room temperature and refrigerated conditions for 2, 4, 6, 8, 10, 12, and 24 hours, microbial item detection was carried out to obtain the total bacterial count, coliform count, mold and yeast count, and Staphylococcus aureus microbial contamination. Results The total bacterial count, coliform count, mold and yeast count of the three fresh cut Citrullus lanatus increased with storage time. After being stored at room temperature for 8, 10 and 12 hours, the total bacterial count of Kirin, Sweet King, and Black Beauty Citrullus lanatus exceeded 10⁵ CFU/g, the coliform count exceeded 100 CFU/g after 8 hours, and the total number of mold and yeast count exceeded 100 CFU/g after 10 hours, under refrigeration conditions, the average total bacterial count of Kirin, Sweet King, and Black Beauty Citrullus lanatus stored for 8 hours exceeded 10⁴ CFU/g; the coliform count, total number of molds and yeasts all exceeded 100 CFU/g after 10 hours of storage. Staphylococcus aureus was detected after 4 hours of storage at room temperature and 6 hours of refrigeration, with a total detection rate of 32.86%. Conclusion Fresh cut Citrullus lanatus pose an increased safety risk due to microbial contamination after being stored at room temperature for 8 hours. Consumers should consume them as soon as possible after purchase and store them at low temperatures if necessary.

Objective To Establish a method for simultaneous determination of 11 kinds of caine anesthetics and their 3 kinds of metabolites in aquatic products by QuEChERS-liquid chromatography-tandem mass spectrometry. Methods The samples were extracted by acetonitrile, dehydrated by anhydrous MgSO₄ and NaCl, purified by 100 mg primary secondary amine (PSA), filtered by 0.22 µm organic microporous membrane, and qualitatively and quantitatively determined by liquid chromatography-tandem mass spectrometry. Results The 11 kinds of caine anesthetes and their 3 kinds of metabolites showed a good linear relationship in the mass concentration range of 0.01-5.00 μg/L, and the correlation coefficients (r) were 0.99529-0.99989. The limit of detection (LOD) and the limit of quantification (LOQ) of 11 kinds of caine anesthetics and their 3 kinds of metabolites were 0.05-2.00 µg/kg and 0.15-5.00 µg/kg, respectively. The 3 kinds of substrates, white shrimp, carp and turbinus were performed at 3 levels: 1 times LOQ, 2-2.5 times LOQ and 10 times LOQ. The recoveries of 11 kinds of caine anesthetics and their 3 kinds of metabolites in 3 samples were 71.3%-114.2%, 71.2%-107.0% and 70.4%-104.5%, and the relative standard deviations were 0.7%-11.2%, 0.5%-11.5% and 0.8%-14.2%. The method was used to detect 50 batches of different varieties of aquatic products in the market. The results showed that 4 batches of products were detected with caine anesthetic, and the other 46 batches were not detected, the detection rate was 8%. The detected items were mainly tricaine, benzocaine, m-aminobenzoic acid and p-aminobenzoic acid, the content of which were 5.68-90.80 μg/kg, and the other 10 kinds of compounds were not detected. Conclusions The method is simple and fast, has high sensitivity, accuracy and precision, and can simultaneously determine a variety of caine anesthetics in aquatic products. It is suitable for the determination of batch samples, and has high practical application significance, and can provide powerful technical support for food safety monitoring.

Objective Microorganisms are significant factors affecting food safety. Contamination of food by microorganisms can lead to spoilage and deterioration, resulting in substantial economic losses. Moreover, many microorganisms possess pathogenicity, and the toxins they secrete are the main cause of foodborne diseases. Therefore, microbiological testing of food has important sanitary and social significance. With the development of the food industry, traditional plate separation methods, due to their long detection times and complex operations, are increasingly unable to meet the current demand for rapid testing. microbiological test tablets are a new type of detection tool, with the advantages of easy operation, no need for culture medium preparation, and space-saving in detection. In recent years, researchers have conducted extensive studies on test tablets for different microorganisms. This article organizes these studies, thoroughly combs the composition and principles of test tablets, analyzes their advantages and existing problems, and has certain theoretical value and practical guidance significance. It is hoped to provide some ideas for the research of microbiological test tablets.

Objective To establish and optimize a method for the determination of perchlorate (ClO₄^-) migration in food contact plastic products by large volume injection-ion chromatography (IC). Methods Water, 3% acetic acid (m:V), 4% acetic acid (V:V), 10% ethanol (V:V), 20% ethanol (V:V), 50% ethanol (V:V), and 95% ethanol (V:V) were selected as food simulants, and the isocratic elution was performed with a mixture of 14 mmol/L anhydrous sodium carbonate and 20% acetonitrile (volume fraction) as mobile phases, with an injection volume of 800 μL and a flow rate of 1.0 mL/min. The separation was performed on a Metrosep A Supp 4 ion chromatography column (250 mm× 4.0 mm, 9.0 μm) and a Metrosep A Supp RP Guard guard column (50 mm×4.0 mm, 9.0 μm) at a column temperature of 30 ℃ with a conductivity detector for the determination and the quantification of the extract by the external standard method. Results The method validation results showed that the method was linear with the linear correlation coefficient of the standard working curve greater than 0.995. The limit of detection was 0.15 μg/kg, the limit of quantification was 0.50 μg/kg, and the recoveries were 83.2%~99.1%, and the precision was 2.7%~9.1% (n=6). Conclusion The method is reliable, convenient, sensitive, has good separation effects, and suitable for the determination of perchlorate migration in food contact plastic products.