Air Pollutants, Occupational ; analysis ; Solvents ; analysis

OBJECTIVETo explore the quantitative relationship between the dust mass concentration and fiber number concentration of refractory ceramic fibres.

METHODSA typical refractory ceramic fiber plant was selected as the study site. Fifty-three paired samples of total dust mass concentration and fiber number concentration were collected using the long-time fixed site mode. The total dust mass concentration was measured according to the GBZ/T 192.1-2007 (Measurement of dust in the air of workplace, part 1: Total dust concentration). Membrane filter method/phase-contrast optical microscopy was used to determine the fiber number concentration. Univariate analysis was used to describe the distribution of the two concentrations and their ratio. Spearman rank correlation, as well as linear regression, logarithmic curve, polynomial, power function, and exponential curve model, were used to explore the relationship between the two concentrations. Results The range of the total dust mass concentration (x) was 0.45-13.82 mg/m3. The range of the fiber number concentration (y) was 0.01-1.04 f/ml. The range of the ratio (x/y) was 4-158. All of the three parameters did not follow normal distribution (P<0.000 1). The two concentrations showed a positive correlation (r,=0.705 22, P< 0.000 1). All the coefficients of determination (R2) of linear regression, logarithmic curve, polynomial, power function, and exponential curve model were relatively low. The trinomial curve model had the highest R2 (0.6848) and the fitted equation was y=-0.001, 1x+0.010 4x2+0.101 4x-0.055 1.

CONCLUSIONThere is a positive correlation between the total dust mass concentration and fiber number concentration of refractory ceramic fibers. However, there is no fixed regression relationship between the two concentrations, and neither is a definite coefficient which can be used to convert each other. The two concentrations cannot be replaced by each other.

Air ; analysis ; Air Pollutants, Occupational ; analysis ; Humans ; Occupational Exposure ; Phthalic Acids ; analysis ; Spectrophotometry ; methods ; Workplace

Air Pollutants, Occupational ; analysis ; Butylene Glycols ; analysis ; Chromatography, Gas ; Workplace

OBJECTIVETo explore the influence factors on determining Tin concentration in air of workplaces with flame atomic absorption spectrometry and to establish an accurate, sensitive and high-efficient method.

METHODSThe different reagents were used to digest the sampling filter membranes and the determining conditions of flame atomic absorption spectrometry were adjusted, then the determining results were compared.

RESULTSWhen 3 ml hydrochloric acid and 0.5 ml nitric acid served as the digesting reagents and the determining conditions of flame atomic absorption spectrometry were adjusted to the best conditions, there was the good linearity in the tested concentration range of Tin, the correlation coefficient was larger than 0.9990. The limit of quantification was 1.0 p.g/ml. The extraction recovery was between 99.6%-102.6%, and the RSD were all less than 5.0%.

CONCLUSIONThe proper kinds and quantity of digestive reagents in pretreatment of the samples should be chosen for the accuracy and precision of the determination according to the influence factors of determination.

Air Pollutants, Occupational ; analysis ; Chromatography, Gas ; methods ; Indenes ; analysis ; Workplace

OBJECTIVETo establish a method for rapid determination of airborne acrylonitrile using a portable gas chromatograph.

METHODSA single standard sample of acrylonitrile was prepared in a laboratory and sampled by the built-in constant flow pump of the portable gas chromatograph. The sample was then preconcentrated by the preconcentrator, thermally desorbed, separated by capillary columns, and detected by a micro argon ionization detector to determine the retention time. Retention time was then used to perform qualitative analysis. Under the set condition of gas chromatography, the external standard method was used to create a standard curve for quantitative analysis of acrylonitrile.

RESULTSThe linear range of acrylonitrile on the portable gas chromatograph was 0.25 to 3.00 mg/m(3). The regression equation was y = 10(-5) x-0.0275, r = 0.9977. The limit of detection was 0.005 mg/m(3), and the lower limit of quantification was 0.25 mg/m(3). The relative standard deviation was lower than 7.09%, and the degree of accuracy was 91.09-105.54%.

CONCLUSIONPortable gas chromatography is a simple, repeatable, and accurate method for rapid determination of airborne acrylonitrile.

OBJECTIVETo establish a rapid gas chromatographic method for determination of o-chlorostyrene in the air of workplace.

METHODThe air samples were collected by syringes, injected directly to the GC system, and then separated by a FFAP capillary column (30 m × 0.53 mm × 0.25 µm), finally determined by a Flame Ionization Detector.

RESULTSA good linear correlation was showed within a range of 0 ∼ 1200 µg/L, with regression formula Y = 14 030 + 7 207X (r = 0.9999). The air sample could be stably stored in the syringe for 5 hrs. The relative standard deviation (RSD) of repeated injection of o-chlorostyrene standard solutions at three different concentration by six times was 1.28% ∼ 1.97%. The minimum detectable concentration was calculated to be 5.2 mg/m(3). Other coexistent violative organic compounds such as styrene, p-chlorostyrene, and m-chlorostyrene didn't interfere with the determination under the experimental conditions of this method.

CONCLUSIONThis method meets the requirement of "Guide for establishing occupational health standards-Part 4: Determination methods of air chemicals in workplace". It is applicable for determination of o-chlorostyrene in the air of workplace.

OBJECTIVETo establish the method of capillary column gas chromatography for determination of ethylene glycol in workplace air.

METHODSEthylene glycol in workplace air was collected with silicone tube, desorbed with methanol, separated with FFAP (nitroterephthalic acid-modified polyethylene glycol)capillary column, and measured with flame ionization detector.

RESULTSThe detection limit of ethylene glycol was 0.41 mg/L, the lower limit of quantification was 1.4 mg/L, the range of measurement was 1.4~163.9 mg/L, and the minimum detectable concentration was 0.3 mg/m3 (1.5 L of air was collected as the sample). This method had a good repeatability, the relative standard deviation was 1.4%~5.2%, the average desorption efficiency was 94.4%~101.7%, and the sampling efficiency was 99.2%~100%. The penetrating capacity of 200 mg silicone was higher than 6.9 mg, and the samples could be preserved for 14 days at room temperature.

CONCLUSIONThe method has a low detection limit, high accuracy, and good precision, which is feasible for determination of ethylene glycol in workplace air.

Air Pollutants, Occupational ; analysis ; classification ; Organic Chemicals ; analysis ; classification ; Workplace