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.

There are problems with insufficient resource utilization, traditional experimental teaching content, and limited scientific research in experimental teaching laboratories and scientific research laboratories in universities. Opening up laboratories is the main way to improve the utilization of laboratory resources. Opening up laboratories is beneficial for enhancing students' innovative thinking and research abilities, promoting scientific research achievements among teachers and students, improving the utilization of laboratory resources, solving laboratory management problems, and promoting the implementation of industry university research work. This paper takes experimental teaching laboratories and scientific research laboratories in universities as research objects, elaborates on the problems of laboratory opening, analyzes the measures that should be taken for laboratory opening, and proposes the mechanism for opening experimental teaching laboratories and scientific research laboratories in universities.

Objective To analyze coal mine occupational health detection and occupational hazard prevention methods. Method The basic concepts of coal mine occupational health detection were expounded, the main methods and processes of occupational health detection were discussed, and occupational disease prevention and control strategies in technology and management were proposed. Results The incidence of occupational diseases in coal mines can be reduced through the comprehensive application of occupational health detection methods and effective prevention and control measures. Conclusion Coal mine occupational health detection and occupational hazard prevention are of great significance to protect the health of miners and improve the level of coal mine safety production.

Ultrasonic flaw detector itself has the characteristics of high detection accuracy, fast detection speed, small size, light weight, and its own ultrasonic non-destructive testing, so it has been widely used in many fields. The measurement accuracy of ultrasonic flaw detector has a non-negligible impact on its function, and it will be affected by various factors in the use process, leading to the deviation of the measurement results. Therefore, it is necessary to do a good job of the measurement verification of ultrasonic flaw detector regularly. The metrological verification of ultrasonic flaw detector is studied and discussed from the Angle of ensuring the performance and measurement accuracy of ultrasonic flaw detector and giving full play to the function of the instrument. In the study, the metrological verification process and precautions of ultrasonic flaw detector are defined, and its dynamic range, horizontal linearity, vertical linearity, sensitivity, false positive rate and resolution are verified. The measurement accuracy of ultrasonic flaw detector has been significantly improved before and after comparative verification, and its own performance can be fully brought into play.

Objective A method for the determination of fluoride ion incoalmine water was established by ion chromatography. Methods The watersamples were determined by ${0.22\mu}\mathrm{m}$ qeuosystem filter membrane with a volume of ${25\mu }\mathrm{L}$ . In ion chromatograpy,the determination of fluoride was completed within $4\mathrm{\;{min}}$ under the anionexchange chromatography of HS-5A-P3 with column temperature at ${35}^{\circ }\mathrm{C}$ , eluted with ${20}\mathrm{{mmol}}/\mathrm{L}\mathrm{{KOH}}$ solution at the rate of ${1.0}\mathrm{\;{mL}}/\mathrm{{min}}$ . Results The linear relation between peak area and concentration offluoride were good. The linear return equation was $\mathrm{y}= {30.26}\mathrm{x}- {0.104}$ .The correlation coefficient of the standard curve was above 0.9997 . Thedetection limit was ${0.002}\mathrm{{mg}}/\mathrm{L}$ . Therecovery of fluoride was ${88.0}\%$ -115.5%. The mean value offluorine ion content in the standard sample was within the range of itsguaranteed concentration. Conclusion Compared fluoride ion selectiveelectrode method, the method has the advantages of small sample amountand can be used to determine other components simultaneously. It issuitable for the determination of fluorine ion content in largequantities of coal mine water.

Objective To evaluate the application value ofhigh-performance liquid chromatography fluorescence detection method fordetermining nitrite in drinking water. Method Collect mineral water, tapwater, and source water as water samples, and use high-performanceliquid chromatography fluorescence detection method to determine.Analyze the detection advantages of this method and the stability ofnitrite derivative 2,3 naphthalene triazole in the water standard. Result The nitrite concentration detected in pure water was ${0.6\mu }\mathrm{g}/\mathrm{L}$ , with goodpeak shape and no impurity interference; The detection limit ofhigh-performance liquid chromatography fluorescence detection method is ${0.3\mu }\mathrm{g}/\mathrm{L}$ , andthe quantitative limit is $1\mathrm{{\mug}}/\mathrm{L}$ ; After derivatization with nitrite, thestability of the derivative is high, and the measurement error is smallwithin 7 days; The recovery rate of nitrite spiking is between90.29%-102.60%, and the precision is between 0.71%-3.66%. Conclusion Thedetermination of nitrite in drinking water by high-performance liquidchromatography fluorescence detection method has the characteristics ofaccuracy and convenience, providing important technical support fordrinking water safety monitoring.

Objective To establish a highly specific method for thedetermination of related substances in salbutamol sulfate injection. Methods HPLC was performed on a column packed with spherical end-cappedoctylsilyl silica gel (Hypersil BDS C8 ${4.6}\times {150}\mathrm{\;{mm}},{3\mu}\mathrm{m}$ ) at the flow rate of ${0.6}\mathrm{\;{mL}}/\mathrm{{min}}$ , thedetection wavelength of ${220}\mathrm{\;{nm}}$ and columntemperature of ${25}^{\circ }\mathrm{C}$ by gradientelution using ${3.45}\mathrm{\;g}/\mathrm{L}$ sodiumdihydrogen phosphate dihydrate solution (adjust to $\mathrm{{pH}}$ 3.0 with phosphoric acid)as mobile phase A, 10 volumes of methanol and 90 volumes of acetonitrileas mobile phase B. Results The chromatograph showed good specificity ofthe peaks of main components and 15 impurities, and the methodverification of 6 of the impurities showed good linear, repeatabilityand recovery. Conclusion The chromatographic peaks of the maincomponents in salbutamol can be completely separated from the 15impurities. The established method is highly specific, easy to operateand can be used for the inspection of related substances in salbutamolsulfate injection.

Objective To establish a new liquid chromatographic methodfor caffeine content in milk tea, to detect the caffeine content ofinstant milk tea in the region, and to make recommendations on healtheffects. Methods The determination was carried out on a Waters highperformance liquid chromatography Symmetry C18 column $\left({{5\mu}\mathrm{m}\times {150}\mathrm{\;{mm}}\times {4.6}\mathrm{\;{mm}}}\right)$ ,the mobile phase was methanol-water $\left({{30}+ {70}}\right)$ at a flow rateof $1\mathrm{\;{mL}}/\mathrm{{min}}$ ,the detection wavelength of ${272}\mathrm{\;{nm}}$ , and the columntemperature was ${35}^{\circ }\mathrm{C}$ . Results Thecorrelation coefficient was $\mathrm{r}={0.9999}$ over the linear range of 1-30 μg/mL, the recoverieswere 97.2%-99.5%, and the method precision was ${0.54}\%$ . Conclusion The method adoptspotassiun ferrocyanide and zinc acetate precipitation centrifugation,which can rapidly extract the effective components of caffeine in milktea and remove the interference of proteins, shorten the pretreatmenttime, optimize the chromatographic conditions, and accelerate thedetection of caffeine.

Objective Exploring the effect of nicotinamide concentration on skin melanin transfer and its mechanism of action, to provide a scientific basis for the development and application of related skin care products and beauty technology. Methods The mechanism of nicotinamide inhibiting the formation of melanin was elucidated, and the main influencing factors of the formation of black spots were analyzed, so as to control the formation and transfer of melanin. The researchers then combined a variety of substances, including arbutin, phenylresorcinol, and vitamin C and its derivatives, to study. Results Nicotinamide was able to effectively inhibit the diffusion rate of melanin by blocking the transfer process of melanin particles to epidermal cells. When used in combination with arbutin, phenylethyresorcinol and vitamin C, its inhibitory effect is more obvious. Conclusion Niacinamide and its synergistic effect with other substances can effectively inhibit the transfer and diffusion of melanin, providing a new way for skin whitening. This discovery provides an important reference for the application and development of related skin care products and beauty technologies.

Given the potential adverse effects of alcohol ether estercompounds in the air on the environment and public health, this studyaims to develop an accurate method for monitoring these compounds. Byanalyzing experimental data, this study selected suitable measurementmethods and instrument reagents, and established a detailed measurementprocess. The research results show that the optimized carbon disulfidedesorption gas chromatography method performs excellently in thequantitative analysis of alcohol ether esters, with a linearrelationship of over ${99.9}\%$ and adetection limit as low as ${0.02}\mathrm{{mg}}/\mathrm{L}$ . Inaddition, the relative standard deviation of this method in precisionand recovery tests is less than 5%, fully demonstrating its highreliability and application value in environmental monitoring.