• Environmental Engineering Research
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• v.18 no.3
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• pp.123-128
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• 2013

The purposes of this study were to determine the efficiency of using a badge-type diffusive sampler to measure formaldehyde concentrations indoors, and to evaluate the uncertainty associated with the use of data from a diffusive sampler. A diffusive sampler using 2,4-dinitrophenylhydrazine (DNPH) reagent was found to be a suitable tool for measuring the formaldehyde concentration in an indoor environment. The agreement between results of the diffusive sampler and DNPH cartridge were good, showing a correlation coefficient of 0.996. The sampling rate for the diffusive sampler was calculated to be 1.428 L $hr^{-1}$, with a standard deviation of 0.084 L $hr^{-1}$. It was found through analysis that the uncertainty associated with the sampling rate and the mass of the formaldehyde transported into the diffusive sampler by diffusion was the dominant contributor to the total.

• Journal of Korean Society for Atmospheric Environment
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• v.29 no.1
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• pp.56-63
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• 2013

This study was aimed at developing and evaluating a diffusive sampling method using a barium hydroxide solution as an absorbent for measuring carbon dioxide ($CO_2$) in ambient air. The collected $CO_2$ concentration was calculated by the change of conductivity resulted in the reaction of $CO_3{^{2-}}$ and $Ba^{2+}$ in aqueous solution. The sampling rate for the diffusive sampler was determined 0.218 mL/min, as obtained from the slope of the linear correlation between the $CO_2$ mass collected by the diffusive sampler and the time-weighted $CO_2$ concentration with the active sampling method. The unexposed blank sampler sealed in aluminium foil-polyethylene laminated packets has remained stable during at least one-month storage period. A good correlation was observed between the diffusive sampler and active sampler with a coefficient of determination of 0.956. This diffusive sampler would be suitable for the indoor $CO_2$ concentration monitoring.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.15 no.3
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• pp.261-269
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• 2005

To investigate the field applicability of a diffusive sampler (3M OVM #3500, passive sampling method) authors conducted a simultaneous measurement of personal organic solvents exposure in the air of the workplaces by charcoal tube with low volume sampler (active sampling method) and diffusive sampler. Samples were collected and analyzed by NIOSH method ($NMAM^{(R)}$) from thirty-eight workers in 12 factories who work in 6 different processes. Geometric mean (GM) and geometric standard deviation (GSD) were used to describe the result. To compare the results of the two methods, paired t-test was used. According to the manual of the exposure assessment of the mixed organic solvents (Ministry of Labor, Korea), Em was calculated. Simple linear regression was used to evaluate the relationship between the two methods. Results were as follows; 1. Eight different solvents (ethyl acetate, n-hexane, toluene, xylene, acetone, isopropyl alcohol, methyl ethyl ketone (MEK), and methyl isobutyl ketone) were detected simultaneously in the two methods and the concentrations of the personal exposure were lower than 0.5 TLV level. The concentration of the charcoal tube method was higher than that of a diffusive sampler in n-hexane and MEK (p<0.05). 2. Em of the charcoal tube method was higher than that of diffusive sampler method but not significantly different and was lower than the OEL (Occupational Exposure Limit) in all 6 processes. 3. There was a significant correlation between the two methods in low concentrations of the 8 organic solvents (p<0.05). In conclusion, there was no difference in charcoal tube method and diffusive sampler method in low concentrations of some organic solvents, diffusive sampler can be applied to assess the personal monitoring in low level exposure.

• Journal of Environmental Health Sciences
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• v.32 no.5 s.92
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• pp.485-491
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• 2006

It is widely known that Environmental Tobacco Smoke(ETS) is not good for health. ETS is composed of a lot of chemicals. So indicators are needed to evaluate the risk of ETS in air. One of the indicators is Nicotine. Active sampler has been used to measure nicotine concentration in air. The experiments were conducted to compare the active sampler method with diffusive sampler in exposure chamber and smoking areas, respectively. Sampling rate was 40.5 ml/min in exposure chamber. Experimental sampling rate (40.5 ml/min) was more than theoretical sampling rate (33.52 ml/min). And the higher was the concentration in air, the higher was experimental sampling rate. The average desorption, rate was 113.6%. The overall precision was 7.31 %. The overall accuracy was 18.96%, which were under NIOSH criteria. The average(GM) concentrations of nicotine by two sampling methods were $8.29{\mu}g/m^{3}$ (active sampler), $7.54{\mu}/m^{3}$ (diffusive sampler) in smoking area and smoking room. There was no regression between active sampler and diffusive sampler ($R^{2}=0.2397$). But slope, coefficient of determination was 1.017, 0.9292, respectively after removing outliers. And the slope (1.017) was close to the theoretical slope (1). In conclusion, this study indicated that diffusive sampler can be used to evaluate concentration of nicotine in air instead of active sampler.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.7 no.1
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• pp.21-31
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• 1997

Toluene, n-hexane, and methyl ethyl ketone(MEK) were exposed to the activated carbon fiber(ACF) and 3M(Model 3500) diffusive samplers under low and high humidity levels. In order to evaluate these two samplers, the sampling capacity, sampling rate, reverse diffusion, and storage stability were obtained. At low humidity level($8{\pm}3%RH$), the adsorption amount of all three organic vapors to the ACF diffusive sampler showed a positive linear relationship up to 8 hours. However, at high humidity level($90{\pm}5%RH$), n-hexane and MEK maintained a positive linear relationship up to 1.5 hrs, but decreased in their adsorption amounts afterwards. On the other hand, the adsorption amount of n-hexane, MEK, and toluene to 3M diffusive sampler showed almost a positive linear relationship up to 8 hours at both humidity levels. At low humidity level, there was almost no reverse diffusion for both 3M and ACF diffusive samplers. However, when the ACF diffusive sampler was used at high humidity level, there was about 52.63% of MEK sample loss and about 92.59% of n-hexane sample loss. The storage stabilities of the ACF and 3M diffusive samplers were both relative stable except for MEK. In the case of MEK, the difference between the analysis of the organic vapor right after the sampling and that of 3 weeks later at room temperature was 45% for the ACF diffusive sampler and 18% for the 3M diffusive sampler. Since the storage stability of the samples stored in a refrigerator was relatively stable, they need to be refrigerated until the analysis is done.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.4 no.2
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• pp.208-223
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• 1994

The purpose of this study was to evaluate the efficiency of diffusive(or passive) sampler in measuring airbone organic solvents. Diffusive samplers are generally simple in construction and do not require power for operation. The efficiency of the diffusive samplers has not sufficiently been investigated in Korea. Three types of samplers were studied in this study. The sampling and analytical results by passive samplers were compared with results by charcoal tube method recommended by NIOSH(National Institute for Occupational Safty and Health). The following characteristics are identified and studied as critical to the performance passive monitors; recovery, reverse diffusion, storage stability, accuracy and precision, face velocity and humidity, n-Hexane, TCE(trichloroethylene) and toluene were used as test vapors. A dynamic vapor exposure system consisting of organic vapor generator and sampling chamber for evaluating diffusive samplers are made. The results of the study are summarized as follows. 1. NIOSH recommands that the overall accuracy of a sampling method in the range of 0.5 to 2.0 times the occupational health standard should be ${\pm}25$ percent for 95 percent confidence level. Among three types of diffusive samplers, sampler A has permeation membrane and samplers Band C have diffusive areas, samplers A and B met the criterion that overall accuracy for 95% confidence level of the samplers were within ${\pm}25$ percent of the reference value. Sampler C had overall accuracy ${\pm}9.6%$ and ${\pm}11.8%$ in hexane and TCE, respectively. The concentration of toluene was overestimated in sampler C with overall accuracy of ${\pm}43.9%$. 2. The desorption efficiencies of diffusive samplers were 96-107%. 3. There was no significant sampe loss during four weeks of storage both with and without refrigeration. 4. There was no significant reverse diffusion, when the samplers were exposure to clean air for 2 hours after sampling for 2 hours at the level of 2 TLY. 5. In case of 8 hours sampling, relative differences(RD) of concentrations between charcoal tube method and diffusive method were 15-39%, 13-46%, and 4-35% for sampler A, B and C, respectively. The performance was poor in 8 hours sampling for multiple substance monitors. 6. At high velocity(100 cm/sec), samplers B and C overestimated the concentrations of organic vapors, and sampler A with permeation membrance gave better results. 7. At 80% relative humidity, samplers showed no siginificant effect. Low humidity also did not affect the diffusive samplers.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.9 no.1
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• pp.173-186
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• 1999

To utilize diffuse sampling of formaldehyde in air, a new sampler was designed. A glass fiber filter was impegnated with 2,4-dinitrophenylhydrazine(DNP) and phosphoric acid and mounted 37mm cassette. The formaldehyde vapor was sampled in the dynamic chamber and measured by high performance liquid chromatograph and compared with solid sorbent tube. The results were as follows ; 1. The desorption efficiencies of diffusive sampler between 97.0% and 100%. 2. the sampling rate is constant as in $58{\sim}61.8m{\ell}/min$ when sampling times are between 120 and 360 min. 3. There was a significant relationship between concentrations of diffusive samples and active samples with the coefficient of determination(R2) of 0.92. 4. Desorbed amount of formaldehyde diffusive sampler was increased by high relative humidity. 5. Wheth diffusive samplers were stored at room temperature or at refrigerator there was no statistically significant difference in the accuracy of result. 6. When the diffusive samplers, which collected formaldehyde vapor, were exposed to clean air for three hours, there was no significant loss of formaldehyde due to reverse diffusion. In conclusion, this study suggest that developed diffusive samplers will be a reasonable substitute for the solid sorbent tube for sampling formaldehyde and practical comparative study of developed diffusive sampler should be performed at workplaces of manufacturing industry.

• Proceedings of the Korean Environmental Health Society Conference
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• 2005.06a
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• pp.371-372
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• 2005

Active sampler has been widely used to measure nicotine concentration in air. The experiments were conducted to compare the active sampler method with diffusive sampler in exposure chamber and smoking areas, respectively. The result of these tests that indicated that passive sampler can be used instead of active sampler in ETS, because coefficient of determination was 0.9292 between active and passive sampling in smoking area

• Journal of Environmental Health Sciences
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• v.35 no.6
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• pp.500-509
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• 2009

Passive samplers have been used for many years for the sampling of organic vapors in work environment atmospheres. Currently, all passive samplers used in domestic occupational monitoring are foreign products. This study was performed to evaluate variable parameters for the development of passive organic samplers, which include the geometry of the device and diffusive length for the sampler design. Four prototype diffusive lengths; A-1(4.5 mm), A-2(7.0 mm), A-3(9.5 mm), A-4(12.0 mm) were tested for adsorption performances to a chemical mixture (benzene, toluene, trichloroethylene, and n-hexane) according to the US-OSHA's evaluation protocol. A dynamic vapor exposure chamber developed and verified by related research was used for this study. The results of study are as follows. The results in terms of sampling rate and recommended sampling time test indicate that the most suitable model was A-3 (9.5 mm diffusive lengths on both sides) for passive sampler design in time weighted average (TWA) assessment. Sampling rates of this A-3 model were 45.8, 41.5, 41.4, and 40.3 ml/min for benzene, toluene, trichloroethylene, and n-hexane, respectively. The A-3 models were tested on reverse diffusion and conditions of low humidity air (35% RH) and low concentrations (0.2 times of TLV). These conditions had no affect on the diffusion capacity of samplers. In conclusion, the most suitable design parameters of passive sampler are: 1) Geometry and structure - 25 mm diameter and 490 $mm^2$ cross sectional area of diffusion face with cylindrical form of two-sided opposite diffusion direction; 2) Diffusive length - 9.5 mm in both faces; 3) Amount of adsorbent - 300 mg of coconut shell charcoal; 4) Wind screen - using nylon net filters (11 ${\mu}m$ pore size).

• Journal of Korean Society for Atmospheric Environment
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• v.21 no.6
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• pp.593-603
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• 2005

Passive sampler using 4-amino-3-hydrazino-5-mercapto-1, 2, 4-triazole (AHMT) was developed to determine formaldehyde in indoor environment. The chromatography paper cleaned by $3\%$ hydrogen peroxide solution was experimently determined as a optimum absorbtion filter for the collection of formaldehyde. The passive sampler with a broad cross-sectional area and a short diffusion length was quite good in sensitivity. The passive sampler and the active sampling method with an impinger were strongly correlated with a correlation coefficient of 0.9848. The limits of detection and quantification of the passive sampler for the measurement of formaldehyde in the indoor environment were 7.5 and 10.2 ppb, respectively. Temperature ($19\∼28^{circ}C$) and relative humidity ($30\∼90\%$) had slight influence on the sampling rate of the passive sampler. However, the increase of flow velocity on the surface of sampler resulted in the increase of sampling rate.