Objective To analyze the correlation between the dry eye symptom and signs in middle-aged and aged people by Lipiview(R) ocular surface interferometry.Methods A total of 170 eyes from 85 middle-aged and aged people (55-80 years old) were examined with Standard Patient Evaluaion of Eye Dryness(SPEED) questionnaire and Lipiview(R) ocular surface interferometry,meanwhile obtaining the consent of the subjects.Then the correlation between the symptom and Lipid Layer Thinckness (LLT) and partial blink rate were analyzed.Results SPEED questionnaire score was 6.13 ±4.60.LLT was(74.88 ± 21.16) nm.LLT variability was 4.47 ± 3.40.The partial blink rate was 0.62 ± 0.36.The Spearman correlation analysis indicated that the nega-tive correlation was shown between the SPEED questionnaire score and LLT (r =-0.823,P =0.000),SPEED questionnaire score and LLT variability(r =-0.268,P =0.018).The positive correlation were found between LLT and Std.Dev of LLT (r =0.339,P =0.030).However,the results of the SPEED score were uncorrelated with partial blink rate (P ＞ 0.05).Conclusion The results from this study demonstrate that correlation among symptom,LLT and LLT variability,but poor correlation between symptom and partial blink rate.

OBJECTIVE: To develop a solvent desorption-gas chromatography method for detecting ethylene glycol monopropyl ether( EGME) in workplace air. METHODS: EGME in workplace air was captured by charcoal tubes and desorbed by methanol-methylene chloride(5∶ 95,V/V),separated by capillary chromatographic column,and detected by flame ionization detector. RESULTS: The good linear range of EGME was 1. 37-1 913. 80 mg/L,and the correlation coefficient was 0. 999 90. The detection limit was 0. 06 mg/L. The minimum detectable concentration was 0. 02 mg/m3.The average desorption efficiency was 97. 81%-104. 70%. The within-run relative standard deviation( RSD) was 1. 94%-2. 99%,and the between-run RSD was 3. 24%-4. 53%. The samples could be stored at room temperature for at least 14 days. CONCLUSION: This method could be used for detection of EGME in workplace air.

Objective: To develop a new solid sorbent tube for capturing glycidyl methacrylate (GMA) in workplace air, and establish a complete set of method. Methods: GMA in workplace air was captured by the new solid sorbent tube filled with carbon aerogel adsorbent, desorbed with solution of 50% (V/V) dimethylformamide-carbon disulfide, separated through capillary chromatographic column, and then analyzed by gas chromatography-flame ionization detector. Results: The linear range of GMA was 0.38-604.80 mg/L, and the related coefficient was 0.999 82. The within-run and the between-run precision were 1.11%-2.80% and 2.53%-4.84% respectively. The average desorption efficiency was 93.20%-94.97%. The minimum quantification concentration and The minimum quantification concentration were 0.02 and 0.07 mg/m³ respectively (3.00 L sample) . Samples could be stored for at least 8 days at room temperature. Conclusion The newly developed solid sorbent tube and its complete set of gas chromatography method is simple, and has high sensitivity and precision, so it can be used for sampling and quantitative detection of GMA in workplace air.

Objective: To establish a solvent desorption-gas chromatography method for determination of dimethyl carbonate (DMC) in workplace air. Methods: The air samples were collected using activated carbon tubes, desorbed by carbon disulfide, separated by dimethylpolysiloxane capillary columns, and detected by a flame ionization detector. Results: The linear range of DMC was 2.14 to 1.07×10⁴ mg/L, and the correlation coefficient was greater than 0.999. The detection limit was 0.14 mg/L, the lower limit of quantification was 0.47 mg/L, the minimum detection concentration was 0.10 mg/m³, and the minimum quantification concentration was 0.32 mg/m³ (based on 1.5 L workplace air). The average desorption efficiency of the method was 96.2% to 102.0%. Both the within-run and between-run relative standard deviations were 0.9% to 2.3%. The samples could be stored for at least seven days at four celsius degree. Conclusion: This method shows high desorption efficiency, high sensitivity, good precision and is simple in using. It can be used for the determination of DMC in workplace air.

ObjectiveTo understand the monitoring result of occupational hazard in the workplace of key industries in Guangdong Province from 2020 to 2023. Methods The data of occupational hazards in the workplace of 20 key industries in Guangdong Province from 2020 to 2023 were collected from the “Workplace Occupational Hazard Monitoring System” of the Chinese Disease Prevention and Control System subsystem. The monitoring result of occupational hazard factors, occupational health training, occupational health examination, occupational protection, detection of occupational hazardous agents such as dust, chemical substances and noise were analyzed. Results A total of 13 058 enterprises from key industries were recruited as the monitoring subjects in Guangdong Province. There were 290 large-, 1 342 medium-, 7 635 small-, and 3 791 micro-enterprises, with small and micro-enterprises accounting for 58.5% and 29.0% of the total, respectively. A total of 7 542 enterprises exceeded the national standard in the detection of occupational hazards, with a rate of 57.8%. A total of 1 942 517 workers from 13 058 enterprises were recruited, with 835 567 workers were exposed to occupational hazards, with a rate of 43.0%. The rate of occupational health training for enterprise leaders, occupational health management personnel, and workers was 71.9%, 73.8%, and 86.5%, respectively. The abnormal rate of occupational health examinations for workers exposed to noise, dust, and chemical agents was 2.0%, 0.6%, and 1.0%, respectively. The distribution rate of dust masks, anti-poisoning masks or face masks, and noise prevention earplugs or earmuffs was 83.3%, 71.3%, and 77.8%, respectively. The rate of installation of dust prevention facilities, anti-poisoning facilities, and noise prevention facilities was 85.6%, 81.2%, and 50.1%, respectively. The rate of exceeded the national standard of dust, noise in the worksites/types and workplaces showed a decreasing trend year by year (all P<0.01), while the rate of exceeded the national standard of chemical agents in worksites/types and workplaces showed an increasing trend year by year in various occupational hazards (all P<0.01). Conclusion Occupational hazards in the workplace of key industries in Guangdong Province are relatively common. The proportion of workers exposed to occupational hazards is relatively high. It is necessary to further improve the use of noise prevention facilities and protective equipment, strengthen occupational health training for enterprises throughout the province and regularly monitor occupational hazards to reduce the risk of occupational diseases.

ObjectiveTo establish a method for the determination of 1,1,1,2-tetrachloroethane (TeCA) and 1,1,2,2-TeCA in human urine using liquid-liquid extraction-gas chromatography. Methods The 5.0 mL urine sample was mixed with 2.0 g anhydrous sodium sulfate and 5.0 mL ethyl acetate, then vortexed mixing. The 1.0 mL extraction was separated by 100% dimethylpolysiloxane capillary gas chromatography column, detected by flame ionization detector, and quantified by an external standard method. Results The linear ranges of 1,1,1,2-TeCA and 1,1,2,2-TeCA were 0.250-50.750 mg/L, with both correlation coefficients of >0.999 9. The detection limit of 1,1,1,2-TeCA in urine was 0.020 mg/L, and the lower limit of quantification was 0.060 mg/L. The average recovery was 88.02%-101.32%, and the within-run and between-run relative standard deviations (RSDs) were 0.11%-0.47% and 0.39%-1.09%, respectively. The detection limit of 1,1,2,2-TeCA in urine was 0.050 mg/L, and the lower limit of quantification was 0.150 mg/L. The average recovery was 93.42%-101.32%, and the within-run and between-run RSDs were 0.28%-1.04% and 0.50%-1.03%, respectively. Both the 1,1,1,2-TeCA and 1,1,2,2-TeCA cannot be stored at room temperature. The 1,1,2,2-TeCA can be stored at 4 ℃ for at least three days. At -20 ℃, the 1,1,1,2-TeCA can only be stored for one day, while 1,1,2,2-TeCA can be stored for at least five days. Conclusion This method has high sensitivity, good specificity, simple sample pretreatment, and more intuitive and reliable results. It can be used to determine the level of 1,1,1,2-TeCA and 1,1,2,2-TeCA in urine of occupational population.

OBJECTIVE: To establish a solvent desorption-gas chromatography method for simultaneous determination of 2-methoxyethyl acetate(2-MEA) and 2-ethoxyethyl acetate(2-EEA) in the workplace air. METHODS: 2-MEA and 2-EEA in workplace air were captured by charcoal tubes and desorbed with solution of 5. 00%(V/V) methanol-methylene chloride,separated through capillary chromatographic column,and then analyzed by gas chromatography-flameionization detector. RESULTS: The linear ranges of 2-MEA and 2-EEA were 1. 50-2 403. 84 and 1. 79-2 871. 20 mg/L,respectively.The correlation coefficient were 0. 999 8. The minimum quantification concentrations were 0. 20 and 0. 09 mg/m~3,respectively(3. 00 L sample). The average desorption efficiencies were 98. 08%-99. 67% and 94. 34%-99. 79%,respectively. The within-run relative standard deviations(RSD) were 1. 77%-3. 51% and 1. 72%-3. 01%,respectively.The between-run RSD were 2. 27%-4. 44% and 2. 31%-4. 19%,respectively. The samples could be stored at room temperature for at least 14 days. CONCLUSION: This method could be used for simultaneous sampling and quantitative detection of 2-MEA and 2-EEA in workplace air.

Objective: To establish a solvent desorption-gas chromatography method for the determination of 1,1,2,2-tetrachloroethane and 1,1,1,2-tetrachloroethane in workplace air. Methods: The 1,1,2,2-tetrachloroethane and 1,1,1,2-tetrachloroethane in workplace air were collected using activated carbon tubes, desorbed with carbon disulfide, and separated and detected by gas chromatography. The quantifications were based on standard curves. Results: The linear ranges of 1,1,2,2-tetrachloroethane and 1,1,1,2-tetrachloroethane were 0.98-395.50 and 0.87-395.50 mg/L, respectively, with the correlation coefficient of 0.999 95. The detection limits were 0.29 and 0.26 mg/L, respectively. The average of desorption efficiency was 92.04%-104.67%. The within- and between-run relative standard deviations were 1.42%-2.09% and 1.63%-6.09%, respectively. The sampling efficiency was more than 98.00%. The samples could be stored at room temperature for at least 14 days. Conclusion: This method can be used in detection of 1,1,2,2-tetrachloroethane and 1,1,1,2-tetrachloroethane in workplace air.

Objective To establish pretreatment conditions of hippuric acid (HA) and methyl-hippuric acid (MHA) in urine and HPLC conditions.Methods HA and MHA in urine were extracted with acetonitrile under acid condition and determinated by HPLC-DAD.The operating conditions by HPLC were C18 column (150 mm× 4.6 mm,5 μm),methanol-0.2％ acetic acid (contained 6.5 mmol/L potassium dihydrogen phosphate) (25:75,V/V) as mobile phase,1 ml/min as flow rate and wavelength was at 254 nm.Results The standard curves for HA,2-MHA and 3-MHA (4-MHA) showed good linearity between 9.91～2 974.20 μg/ml (r=0.999 98),1.91～ 573.60 μg/ml (r=0.999 84) and 2.00～598.65 μg/ml (r=0.999 85),respectively.The mean recoveries were 96.38％～98.01％,83.17％～94.05％,103.22％～104.45％,respectively.The within-run precision were 0.50％～ 1.20％,0.51％～1.59％,0.49％～0.95％,respectively,and the between-run precision were 1.70％～3.20％,1.30％～ 2.67％,0.86％～2.74％,respectively.The detection limit of HA,2-MHA and 3-MHA (4-MHA) were 0.18 μg/ml,0.46 μg/ml and 0.12 μg/ml,and the low determination concentrations of the method were 0.36 μg/ml,0.92 μg/ml and 0.24 μg/ml (1 ml urine).The urine can be kept 15 days at 4 ℃ refrigerator without significantly loss.Conclusion This method with simply pretreatment conforms to the relevant requirements of guide for establishing occupational health standards-part 5:determination methods of chemicals in biological materials.It can be used to detect HA and MHA in urine for occupational population exposure to toluene and xylene.

Objective To investigate the method of portable gas chromatography-mass spectroscopy (GC-MS) for the determination of common volatile organic compounds in air.Methods The static volumetric method was used,with highly purified nitrogen gas as the diluents gas,to prepare the mixed standard gas of common volatile organic compounds with various mass concentrations.A portable GC-MS handheld probe was used for sampling and measurement,retention time and characteristic ion were used for qualitative analysis,and the full-scan mode was used for quantitative analysis.Results The correlation coefficient of 12 volatile organic compounds determined by this method was higher than 0.999.The minimum detection mass concentration was 0.02～0.12 mg/m3,and the minimum quantitative mass concentration was 0.07～0.40 mg/m3.The relative standard deviation of precision was 4.10％～12.50％;the relative deviation of acetone,benzene,methylbenzene,and dimethylbenzene was-13.56％,9.03％,-10.82％,and 8.67％,respectively.Conclusion Portable GC-MS method can be used for the qualitative analysis and quantification of volatile organic compounds in occupational hazard factors and provide technical supports for identification of occupational hazard factor.