This article aims to study the influence of electromagnetic interference on the testing of electric energy meters and corresponding protective measures. By combining experimental and theoretical analysis, this study focuses on the impact of electromagnetic interference on the accuracy of electric energy meter testing, including measurement errors, data instability, and equipment damage. Based on these factors, this article proposes protective measures against electromagnetic interference, including the application of physical shielding technology, reasonable design of filters, and strict attention to the testing of electric energy meters. The results indicate that electromagnetic interference can lead to increased errors in electric energy meter testing, which can cause malfunctions and even incorrect operations. To minimize the impact of electromagnetic interference, this article proposes a series of effective protective measures, including reasonable wiring, installation of filters, and use of shielded cables. These measures have achieved good results in practical applications and significantly improved the accuracy and stability of electric energy meter testing.

Objective To find better conditions and methods to improvethe accuracy and reliability of the measurement by evaluating andanalyzing the total molybdenum uncertainty in soil. Methods The contentof total molybdenum in soil was determined by inductively coupled plasmamass spectrometer with three acid digestion. Results The detection limitof the method was ${0.011}\mathrm{{mg}}/\mathrm{{kg}}$ , thecorrelation coefficient $\mathrm{R}$ of the calibration curve was 0.9999, the recovery was ${97.8}\%$ -105.6%, and the precision of themethod was 2.49%. The extended uncertainty of the method for thedetermination of total molybdenum content in soil was $\left({{0.660}\pm {0.03}}\right)\mathrm{{mg}}/\mathrm{{kg}}\left({\mathrm{K}=2}\right)$ . Conclusion By analyzing the main sources affectingthe uncertainty of measurement, the factors affecting the uncertainty ofthe whole process of determination, such as repeatability, curvefitting, standard solution, sample constant volume, sample weighing,glass measuring tools and sample digestion process were analyzed.Firstly, various conditions during the digestion process, such asdigestion temperature and digestion time, should be strictly controlledto reduce the sample loss. Secondly, microwave digestion, high pressuredigestion and other technologies can be used to optimize thepre-treatment mode to improve the accuracy and reliability of themeasurement results.

Objective To verify the experimental method of erythromycin ointment. Methods Three batch numbers of erythromycin ointment (S1~S3) were selected and divided into three washing methods: test group and positive and negative control group (test article control group and bacterial solution control group). The microbial limit detection method of erythromycin ointment was analyzed by test. Results The recovery ratio of oxygen bacteria, yeast, mold and added bacteria required for different batches of erythromycin ointment in the test is between 0.5 and 2, and the inhibition of microbial strains of erythromycin ointment test can be adopted by membrane filtration method. Therefore, all the methods can effectively eliminate the antibacterial components of erythromycin ointment, and the experimental results can truly reflect the microbial contamination of erythromycin dye ointment. Conclusion The application of centrifugal method in antibacterial removal will not affect the microbial limit test of erythromycin ointment.

By examining the fundamental concepts, classifications of metrological testing, and its roles in ensuring product quality, constructing a foundation for supervisory technology, and facilitating legal enforcement, this paper elucidates how metrological testing technology fosters standardized corporate production, enhances product quality control, and sustains market order. Integrating contemporary technological trends, notably advancements in intelligent inspection technologies, it prospects the future trajectory of metrological testing within the strategy of building a strong quality nation, while proposing strategies to enhance the emphasis on technology, cultivate professional talent, and refine management mechanisms. The research herein underscores the pivotal role of metrological testing technology as a pillar of the quality assurance system, thereby promoting industrial upgrading and securing high-quality economic development.

Objective To understand the monitoring situation of environmental conditions in inspection and testing institutions, analyze existing problems, and provide corresponding countermeasures. Method A self-designed questionnaire was used to conduct a survey and analysis of laboratory environmental monitoring factors in testing institutions. Result 183 inspection and testing institutions were surveyed, and the environmental conditions involved in the laboratories were mainly concentrated in temperature, humidity, microbial pollution, acidity and alkalinity, toxic corrosion, toxic and harmful gases, etc. 96.17% of the laboratories were involved in temperature and humidity, and 83.06% of the laboratories had already carried out environmental condition monitoring. The main environmental conditions monitored were temperature and humidity, accounting for 86.34%, and less than 25% were monitored for current, voltage, light, pressure, noise, vibration, harmful and toxic gases. Only 18.03% of inspection and testing institutions have carried out information monitoring, while other institutions still carry out monitoring and registration through traditional manual recording. 9.84% of inspection and testing institutions have established data models and trend warnings for inspection and testing environmental conditions. Conclusion Inspection and testing institutions involve a wide variety of environmental conditions during the testing process and have complex monitoring requirements. There are still certain shortcomings in the integration of monitoring technology, dynamic monitoring, and monitoring coverage. It is necessary to establish an environmental condition monitoring information platform, establish a hazard trend warning mechanism through data models, and achieve environmental condition monitoring optimization mechanism and intervention management.

Objective Analyze and summarize the factors and precautions that affect the use of N, N-diethylphenylenediamine spectrophotometry for the determination of sulfides in water through experimental analysis. Methods N,N-diethyl-p-phenylenediamine spectrophotometry was used for the determination of sulfide in water. The accuracy and precision of the method were verified by the standard samples with known sulfide content, and all aspects of the experiment were analyzed. Result The N,N-diethyl-p-phenylenediamine spectrophotometry method for the determination of sulfides in water meets the analytical requirements in terms of linearity, precision, and accuracy, making it suitable for the detection of sulfides in clean water. Conclusion When doing the experiment, attention should be paid to sampling, preparation and absorption of standard solutions, and preparation of colorimetric solutions etc. in order to achieve satisfactory results.

Objective To explore the pathogenic factors causing outbreaks of bacterial foodborne diseases. Methods Collecting anal swabs, food retention samples, and food processing tool application samples from patients affected by this epidemic, refer to "Microbiological Testing of Food Hygiene" (GB/T 4789.4-2016、GB/T 4789.5-2012、GB/T 4789.6-2016, GB/T 4789.7-2013, GB/T 4789.10-2016) and "National Clinical Testing Operating Procedures" (Fourth Edition). Results Aeromonas sobria was detected in food samples from little yellow croaker and anal swabs from two patients. Aeromonas hydrophila was detected in a kitchen appliance application and one patient's anal swab. Conclusion This was a rare outbreak of foodborne disease caused by mixed Aeromonas, In the diagnosis and treatment of intestinal infectious diarrhea, in addition to considering common intestinal pathogenic bacteria, rare pathogenic bacteria such as Aeromonas should not be ignored to avoid clinical diagnosis and treatment difficulties.

Objective At present, the systematic study of heavy metals releasing law from ceramic disc sealed water faucet is lack in domestic. At the same time, nozzle production enterprises also lack relevant knowledge, so it is necessary to study this to provide a scientific basis for the green and sustainable development of the nozzle industry. Methods Through the laboratory simulation method, the inductively coupled plasma mass spectrometer was used to analyze and test the precipitation of heavy metal pollutants in the nozzle, and systematically studied the precipitation law of heavy metal pollutants in the ceramic sheet sealed nozzle. Results Through testing and analysis, the material of the surface nozzle material also determines the precipitation type of heavy metal pollutants. The immersion time and the concentration of inorganic salt in water quality are directly proportional to the precipitation of heavy metals. The lead brass nozzle effectively reduces the precipitation of lead and chromium heavy metals through the lead removal process; the precipitation of lead is reduced by 81% to 86%, and the precipitation of chromium is reduced by 52% to 56%. Conclusion Enterprises can choose suitable materials and processes to produce nozzles according to their own conditions. Consumers should avoid exposure to excessive heavy metals according to their use.

The current national standard employs the phenol-sulfuric acid method for quantifying the curdlan content. However, due to inadequate dispersion of some curdlan particles in the solvent caused by agglomeration during dissolution in a 0.1mol/L sodium hydroxide solution, the results of content detection were found to be unstable. The samples were treated by magnetic stirring, homogenizer dispersion and ethanol dispersion. It was found that: The ethanol effectively disperses the curdlan sample in the sodium hydroxide solution, preventing it from agglomerating. The ethanol method effectively and efficiently addresses the pain point in determining the content of curdlan, offering valuable insights for enhancing the detection methodology.

Objective Comparison of two methods for determining ammonium ion content in ambient air${\mathrm{{PM}}}_{2.5}$. Methods $1/4$ of the quartz filter membrane used to collect ambient air particles${\mathrm{{PM}}}_{2.5}$ was cut into pieces, and ultrasound extracted by ultra-pure water, then centrifuged and filtered, and last the content of ammonium ion in${\mathrm{{PM}}}_{2.5}$ was respectively determined by flow injection method and ion chromatography. Result The fitting curve of${\mathrm{{NH}}}_{4}^{+ }$ measured by ion chromatography in the range of${0.5}\sim {10.0}\mathrm{{mg}}/\mathrm{L}$ is$\mathrm{y}= {0.0710}+ {0.2214}\mathrm{x}- {0.0058}{\mathrm{x}}^{2},\mathrm{r}= {0.9997}$ . The detection limit of${\mathrm{{NH}}}_{4}^{+ }$ in${\mathrm{{PM}}}_{2.5}$ is calculated to be${0.017}\mathrm{{\mu g}}/{\mathrm{m}}^{3}$ , with a quantification limit of${0.068\mu }\mathrm{g}/{\mathrm{m}}^{3}$ , the recovery rate is between${91.0}\%\sim {96.6}\%$ , and the RSD is${0.05}\%\sim {0.08}\%\left({\mathrm{n}= 6}\right)$ . The linear relationship of ammonium ion concentration measured by flow injection analysis in the range of${0.02}\sim {1.00}\mathrm{{mg}}/\mathrm{L}$ is good, with$\mathrm{y}= {22.576}\mathrm{x}+ {0.1333},\mathrm{r}= {0.9999}$ . The detection limit is${0.003}\mathrm{{\mu g}}/{\mathrm{m}}^{3}$ , and the quantification limit is${0.012\mu }\mathrm{g}/{\mathrm{m}}^{3}$ with the recovery rate of${105}\%\sim {114}\%$ and the RSD between${0.54}\%\sim {2.06}\%\left({\mathrm{n}= 6}\right)$ . Using the two methods to measure 16 filter membrane samples, there was no statistically significant difference in the measurement results$\left({\mathrm{t}= {1.080},\mathrm{P}> {0.05}}\right)$. Conclusion Both of the two methods have a good linear relationship, with good precision and accuracy. Compared with ion chromatography, flow injection analysis has the advantages of lower detection limit and shorter detection time.