Objective Isolate and identify microorganisms that cause rancidity in vacuum packed rice dumplings, thereby helping enterprises to improve product quality and control of food safety. Methods Bromocresol purple dextrose broth and cooked meat medium base were used to cultivate the acescent rice dumplings; the microorganisms were isolated and purified by scribing in Rose bengal agar, Nutrient agar, the isolated strains were identified by colony morphology observation, cell morphology observation, 16S rRNA sequence analysis, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The isolated strains were inoculated into commercial sterilized rice dumplings respectively to verify that two strains caused rancidity of rice dumplings. Results Two isolated strains, namely Lelliottia amnigena and Wickerhamomyces anomalus, caused rancidity of rice dumplings. Conclusion Lelliottia amnigena and Wickerhamomyces anomalus in vacuum-packed rice dumplings can cause rancidity.

Objective To evaluate the risk of pesticide residues in cucurbit vegetables in Guizhou Qiandongnan Prefecture. Methods LC-MS and GC-MS was used for determination of residues of the level of 50 pesticide residues in cucurbit vegetable samples collected randomly from Guizhou Qiandongnan Prefecture. Results It showed that Pesticide residues were detected in 15 samples of 100 cucurbit vegetables, 8 pesticides were detected, 20 times in total, The average value of food safety index in cucurbit vegetables related to pesticide residues did not exceed the national maximum residue limit in Guizhou Qiandongnan Prefecture. Conclusion Our findings suggest that the potential hazard level of pesticide residues in cucurbit vegetables in Guizhou Qiandongnan Prefecture is acceotable.

Objective To trace the source of a foodborne disease outbreak caused by consuming smoked meat pancakes contaminated with Salmonella enteritidis. Methods Epidemiological investigations were carried out on 8 patients, samples of relevant environment, food and feces were collected, laboratory tests were carried out according to national standards. After bacteria enhancement, suspicious colonies were selected for biochemical identification, and the six strains of Salmonella detected underwent serum agglutination with standard diagnostic sera, drug sensitivity test and pulsed field gel electrophoresis. Result There were 8 cases of this incident, and out of the 6 samples, 6 strains of Salmonella enteritidis were isolated. The detection rates of Salmonella in the food, environmental samples, and cases feces were all 100%. The drug sensitivity test results showed that all strains were resistant to 6 drugs, and the drug resistance spectrum was CT-CTX - TET - CIP - AMP - AMS. They were sensitive to CHL, SXT, ETP, MEM, CAZ, CZA, TIG, AZM, and AMI. The PFGE bands of the 6 strains were consistent, with the homology of ${100}\%$ , and that showed the same clone. Conclusions This incident is a foodborne disease outbreak caused by consuming smoked meat pancakes contaminated with Salmonella enteritidis.

Objective To evaluate the precision and accuracy level of four Dimai DM79x blood cell analyzers in the most suitable working state of our department's daily indoor quality control by comparing the indoor quality control data, so as to improve the accuracy and consistency of test results. Methods In February 2023 (28 days), the indoor quality control data of four laboratory instruments using original low, medium and high fixed value quality control products and daily testing of a random outpatient fresh patient sample were collected. The items included: White blood cells (WBC), red blood cells (RBC), hemoglobin (HGB), hematocrit (HCT), platelets (PLT), mean red blood cell volume (MCV), mean red blood cell hemoglobin volume (MCH), mean red blood cell hemoglobin concentration (MCHC) calculated mean (X), standard deviation (S) and coefficient of variation (CV), Coefficient of variation index (CVI) and standard deviation index (SDI) were used as precision and accuracy evaluation indexes respectively. Result The statistical analysis showed that the blood cell analysis of the DM79x instrument included 8 parameters, including WBC, RBC, HGB, PLT, HCT, MCV, MCH and MCHC. The coefficient of variation index of CVI of each instrument was different, and the indoor quality control result of SDI was <2.0. The measured values of CVI and SDI of fresh sample comparison data are all within the required range. Conclusion Four Dimai DM79x automatic blood cell analyzers in our department have good precision and high accuracy by comparing the indoor quality control data between laboratories. The performance of the instrument can meet the work needs of clinical laboratories. Moreover, the accuracy and consistency of the results in different instruments can be ensured by comparing the fresh samples of patients.

ABSTRACT: The main purpose of building a carbon neutral laboratory is to develop low-carbon technologies and solutions, aiming to reduce energy consumption and carbon emissions to solve environmental problems. Through advanced technology and practical exploration, establish and improve a low-carbon economic system, expand the scale of related industries, and promote economic structure optimization. The construction plan of the testing laboratory studied in this article has negative emissions after measures such as independent emission reduction, renewable energy, and carbon sequestration during the operation phase, which can be defined as a carbon neutral laboratory. The construction of zero carbon laboratories is one of the important actions for global environmental protection and energy conservation and emission reduction, and is also regarded as the actual implementer of the ecological civilization concept advocating sustainable development. From this, we can gain a deeper understanding and promote the development direction of humanity towards a sustainable and low-carbon future.

Objective: To achieve rapid on-site detection of benzoic acid and sorbic acid, two common preservatives in cosmetics, and improve detection efficiency and on-site detection capabilities. Methods: A portable Raman spectrometer which used silver nanoparticles as the enhancement substrate for surface enhanced Raman spectroscopy (SERS) was used to detect benzoic acid and potassium sorbate in cosmetics. Results: Benzoic acid and sorbic acid had characteristic Raman peaks at ${1157}{\mathrm{\;{cm}}}^{-1}$ and ${871}{\mathrm{\;{cm}}}^{-1}$,respectively. Further research showed that the concentrations of benzoic acid and sorbic acid were linearly correlated with the intensity of their characteristic Raman peaks, making quantitative detection possible. This was confirmed by traditional liquid chromatography, and the quantitative results were consistent. Conclusion: This SERS method has the advantages of simplicity, speed, and efficiency, and is expected to achieve rapid on-site detection of preservatives.

Objective To develop an ultra high performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) to identification of the feeding status of turtle and turtle shell components in different batches of Gejie Dingchuan Pills. Methods This study used the identification method of characteristic peptides of Animal medicine for reference, Enzymatic hydrolysis of different batches of Ge jie Ding chuan Pill samples using trypsin, and Identification by using the ultra high performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). The characteristic ion pairs of Testudinis Carapax et Plastrum and Trionycis Carapax were as detection ion pairs. The positive electrospray ionization and multiple reaction monitoring were adopted. Result: 51 batches of Gejie Ding chuan Pills form 8 companies have all detected turtle shell components, but no other turtle source components have been detected. Conclusion This method is raliable for identification of Testudinis Carapax et Plastrum and Trionycis Carapax form Ge jie Ding chuan Pill.

Objective: This study aims to explore a method for determining the concentration of free amino acids in cell culture media based on ultra performance liquid chromatography (UPLC). Methods Researchers used UPLC technology combined with optimized sample processing Methods to efficiently and accurately determine free amino acids in cell culture medium. Results The research results indicate that the UPLC method can quickly and reliably determine the concentration of free amino acids in cell culture medium, providing an effective means for monitoring and optimizing cell culture in the biopharmaceutical industry. Conclusion Accurate determination of amino acid concentration not only helps to better understand the dynamic changes of key nutrients in cell culture media, but also provides important data support for process optimization in the production process.

Objective In the present paper, the influences of matrix effect (ME) to the quantification of imidacloprid, thiamethoxam and clothianidin in ginger and banana were evaluated, and especially, the influencing factors and compensating means of matrix effect in LC-MS/MS analysis were proposed. Methods In this research, the matrix effects of three neonicotinoid insecticides in ginger and banana were evaluated by LC-MS/MS analysis after QuEChERS pretreatment. Both matrix-matched calibration curves and solvent calibration curves were established for the assessment of matrix effect. Results The linear regression coefficients of the matrix-matched calibration curves were all above 0.999 and the precision of the measured sample results was better than that of the solvent standard. The recoveries and relative standard deviations of all compounds at matrix-matched calibration curves were 86.7%~103.0% and 2.1%~8.3%, respectively. Conclusion Matrix effects can compromise the precision and accuracy of the analysis results. These results also indicated that matrix effects were mainly affected by matrix concentration, the types and samples of matrices and the overall chemical structure of the pesticide. The linear regression coefficients and precision as well as accuracy were more satisfactory for all the pesticides when matrix-matched standard was used, which reflected an excellent compensating means of matrix effect. This can improve the accuracy of quantitative results, which is feasible in routine testing, and is of great significance for ensuring the quality and safety of ginger and banana products.

Objective To evaluate the uncertainty evaluation for the determination of imidacloprid in Caidian lotus root by ultra performance liquid chromatography-tandem quadrupole mass spectrometry. Methods According to GB/T 20769 - 2008 Determination of 450 pesticides and related chemicals residues in fruits and vegetables-Liquid chromatography-tandem mass spectrometry, the content of imidacloprid in Caidian lotus root was determined and the mathematical model was built. According to the provisions of JJF 1135-2005 Evaluation of measurement uncertainty in chemical analysis and JJF 10591-2012 Technical specification for evaluation and representation of measurement uncertainty, the uncertainty was quantified by scientific analysis, and the extended uncertainty of imidacloprid content in Caidian lotus root　was finally calculated. Results When the residue imidacloprid in Caidian　lotus root was ${0.322}\mathrm{{mg}}/\mathrm{{kg}}$ , the　relative standard synthetic uncertainty was 0.08689 and the expanded　uncertainty was ${0.0560}\mathrm{{mg}}/\mathrm{{kg}}$ . The　determination results were　 $\left({{0.322}\pm {0.0560}}\right)\mathrm{{mg}}/\mathrm{{kg}},P ={95}\%, k = 2$ . Conclusion The main sources of uncertainty in　the determination of imidacloprid in Caidian lotus root by ultra　performance liquid chromatography-tandem quadrupole mass spectrometry　are the preparation of standard solution, sample pretreatment and　measurement process of the measuring instrument.