ABSTRACT
Objective To design a VDT operation related upper extremities fatigue detection system using keying duration (KD)as an indicator of fatigue and to execute experimental verification.Methods The system included the software part able to calculate,compare and analyze KD and hardware part able to support normal VDT operations.Subjects finished typing task under controlled condition while the system was running. The flexor digitorum superficialis (FDS), extensor digitorum communis(EDC),extensor carpi radialis(ECR),extensor carpi ulnaris(ECU)muscle fatigue were retrieved by sEMG method and standardized questionnaire. Results As the number of keystrokes increased, KD shortened by 1.3%, FDS MVC% dropped by 22.9%,and EDC MVC% decreased by 47.9%.The perceived level of typing fatigue also increased.Conclusion Results revealed KD's change with fatigue,showing the possibility of using KD as an indicator of fatigue and validating the feasibility and effectiveness of the system design.
ABSTRACT
<p><b>OBJECTIVE</b>To establish a method for determining the content of 2,4-toluenediamine, a urinary metabolite of toluene diisocyanate, by gas chromatography.</p><p><b>METHODS</b>Urine samples were collected, and acidification, extraction, derivatization, separation with a capillary column, and detection with an electron capture detector were performed. The target compound was qualified by retention time and quantified by peak area.</p><p><b>RESULTS</b>The concentration of 2, 4-toluenediamine showed a linear relationship with peak area within 0.0∼40 ng/ml, with a correlation coefficient 0.9995; the limit of detection was 0.44 ng/ml, the lower limit of quantification was 1.47 ng/ml, the relative standard deviation was 1.85%∼4.05%; the recovery rate was 97.98%∼99.28%.</p><p><b>CONCLUSION</b>The method has the advantages of high sensitivity and high accuracy and can be used for determination of 2, 4-toluenediamine in urine.</p>
Subject(s)
Humans , Chromatography, Gas , Methods , Occupational Exposure , Phenylenediamines , UrineABSTRACT
<p><b>OBJECTIVE</b>To establish a gas chromatographic method for detecting 2-butoxy ethanol in the air of workplaces.</p><p><b>METHODS</b>After the air samples were collected with activated carbon tubes and desorbed with methylene chloride/methanol, the target toxicant was separated with FFAP capillary columns and detected with flame ionization detector, qualified by retention time and quantified by peak area.</p><p><b>RESULTS</b>The linear range of 2-butoxy ethanol in air of workplace was 56.3 ∼ 901.0 µg/ml, the correlation coefficient was 09999. The limit of detection was 2.0 µg/ml. The limit of quantity was 5.0 µg/ml. The minimal detecting concentration was 0.27 mg/m(3) in the condition of 7.5L sampling volume and 1ml desorbed volume. Relative standard deviation was 3.04% ∼ 7.93% and the recovery was 92.7% ∼ 95.5%.</p><p><b>CONCLUSION</b>In present study the detecting method with high sensitivity, precision and accuracy can be used to determine 2-butoxy ethanol in the air of workplaces.</p>
Subject(s)
Air Pollutants, Occupational , Chromatography, Gas , Methods , Ethylene Glycols , WorkplaceABSTRACT
<p><b>OBJECTIVE</b>To evaluate the uncertainty of measurement result of urinary fluoride and to provide quality assurance for determinations.</p><p><b>METHOD</b>The investigation was conducted, according with principles and methods for uncertainty evaluation.</p><p><b>RESULTS</b>The uncertainty of the combined standard of present method was 2.86 %. For the sample containing 4.47 mg/L urinary fluoride, the expanded uncertainty was 0.26 mg/L.</p><p><b>CONCLUSION</b>The uncertainty of the present method was mainly from the sample repeatability, the preparation of standard solution, the linearity of the calibration curve and instruments and so on.</p>
Subject(s)
Fluorides , Urine , Ion-Selective Electrodes , Reference Standards , Quality Control , Uncertainty , Urinalysis , MethodsABSTRACT
<p><b>OBJECTIVE</b>To establish a ion chromatography method for determination of phosphorus oxychloride in the air of workplace.</p><p><b>METHOD</b>The phosphorus oxychloride in the air of workplace was collected by absorb liquid and turned into hydrochloric acid, then separated in column and detected with conductivity detector, qualified by elution time and quantified by peak height or peak area.</p><p><b>RESULTS</b>The linear range of phosphorus oxychloride in air of workplace was 0.72 ∼ 5.76 µg/ml with its correlation coefficient 0.9999. The detecting limit of the method was 0.12 µg/ml. The smallest detecting concentration of the method was 0.08 mg/m(3) for 15 L sampling air. Relative standard deviation was 3.3% ∼ 6.2% and the recovery was 97.8% ∼ 103.8%. The sample could be resaved at room temperature at least for seven days.</p><p><b>CONCLUSION</b>The indicators of the method correspond GBZ/T 210.4-2008«Guide for establishing occupational health standards-Part 4: Determination methods of air chemicals in workplace». It is a good method to determine phosphorus oxychloride in the air of workplace.</p>