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- Emission test chamber (8)
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- Biocides (2)
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Investigation of an active air sampling strategy for biocides, PCBs and PAHs at low air change rates
(2013)
The aim of this study was to develop a low volume air sampling strategy for biocides, polychlorinated biphenyls (PCB) and polycyclic aromatic hydrocarbons (PAH) at low air change rates. Firstly a method of measurement for the GC-MS-MS system had to be created before an adsorbent for the air sampling of these compound classes was selected in elution experiments with target compound solutions. The key requirements for the adsorbent were that it had to engender a faster and easier work-up process while reducing solvent consumption, as it is not the case for the frequently used polyurethane foam (PUF) and XAD adsorbents. Using the selected adsorbent, air sampling quality was tested and compared with the one of PUF in experiments performed in a Micro-Chamber/Thermal Extractor™ (μ- CTE™, Markes International) with target compound solutions. To achieve air sampling under the aforementioned conditions the influences of temperature, air circulation, air change rate and relative humidity on the emission behavior of the selected biocides, PCBs and PAHs were investigated. This investigation was carried out with self soaked wood samples in low volume air sampling experiments in a μ-CTE, 23 l and 24 l emission test chambers and 27 l showcases. Furthermore, an active air sampling strategy for biocides, PCBs and PAHs at low air change rates was successfully tested in a 24 l emission test chamber. Sampling volumes of 24-50 l were tested with the developed low volume air sampling strategy with limits of quantification between 1-27 μg m-3. A styrene divinylbenzene polymer was selected as a suitable adsorbent and sampling of at least 100 ng μl-1 of biocides, PCBs and PAHs without breakthroughs were possible with 200 mg of this polymer. This corresponds to a concentration range of 3000-6250 μg m-3 for these low sampling volumes. The low volume air sampling method developed in this study was successfully applied in projects investigating real wood samples in the μ-CTE as well as in low volume indoor air samples. In these experiments the applicability of the method was partly compared with a method using a different adsorbent.
Since semi-volatile organic compounds (SVOCs), including biocides and polychlorinated biphenyls (PCBs), occur indoors as well as outdoors, air sampling adsorbents and measuring methods for all these compounds are indispensable. This paper presents the initial steps in the development of such a method, the aim of which is the analysis of selected compounds in the above-mentioned classes using low air sampling volumes and air-exchange rates close to zero, as is common in museum showcases. For measurements under easily controlled conditions, a micro-chamber system was used at different temperatures. A surface modified styrene divinylbenzene (SDVB) polymer was selected as the air sampling adsorbent for the elution experiments. After successfully performing pretests using the micro-chamber system with target compound solutions, the emissions of these compounds from self-soaked wood samples and con-taminated wood samples were investigated for method development.
Photocatalytical degradation of selected volatile organic compounds in emission test chambers
(2014)
This work focuses on the photocatalytical degradation of selected volatile organic compounds (toluene, butyl acetate, phenol and limonene) under UV-light and blue LED-light (λ = 444 nm) at different relative humidities. Ceramic tiles coated with titanium dioxide were used as photocatalytical active material. The experiments were performed in 20 l emission test chambers with two different kinds of pollutant supply. Toluene was the compound with the highest degradation rate in all performed experiments. A degradation rate of 24 % was obtained under blue LED-light and a relative humidity of (50 ± 5)% and a degradation rate up to 80 % was obtained under UV-light in dry air.
A method for the determination of very volatile organic compounds (VVOC) in air was developed and successfully tested for methanol and ethanol. Carbotrap 300 (R) (a multi-bed tube using Carbopack C (R), Carbopack B (R) and Carbosive SIII (R)) was selected as sorption material for thermal desorption and tested for its suitability for emission test chamber measurements. The adsorption behaviour and the chromatographic results are influenced negatively by spiking aqueous solutions on the adsorption medium for calibration purposes. The latter effect can be reduced by blowing dry air across the adsorbent to remove the adsorbed water. Detection and quantification limits were determined for a GC-FID system and compared to GC-MS. The applicability of the method was tested with a methanol eliminating silane modified polymeric adhesive (SMP-adhesive for parquet) in an emission test chamber.
The aim of this study was the development of a low volume air sampling strategy for biocides and polychlorinated biphenyls (PCB) at low air change rates in modern, air-tight showcases as they are present in museums. Lindane, pentachlorophenol, dichlofluanid, tolyfluanid, isodrin, p,p-dichlorodiphenyl trichloroethane and permethrin were the biocides and PCB 28 and PCB 153 were the PCBs studied, all of which are semi volatile organic compounds (SVOC). Their occurrences in the museum environment originate from various sources e.g. preventive treatment of organic exhibits or organic building materials. Exhibits are long-term exposed to these pollutants due to storing in showcases or other storage equipment at low air change rates. To achieve air sampling under the aforementioned conditions the influences of temperature, air circulation, air change rate and relative humidity on the emission behavior of the selected biocides and PCBs had to be determined. This was carried out with pre-soaked wood samples in low volume air sampling experiments using 27 L test showcases and 23 L and 24 L emission test chambers and also diffusive sampling with glass as the sampling material.
A method for the determination of very volatile organic compounds (VVOC) in air was developed and successfully tested for methanol and ethanol. Carbotrap300® (a multi-bed tube using Carbopack C®, Carbopack B® and Carbosive SIII®) was selected as sorption material for thermal desorption and tested for its suitability for emission test chamber measurements. The adsorption behaviour and the chromatographic results are influenced negatively by spiking aqueous solutions on the adsorption medium for calibration purposes. The latter effect can be reduced by blowing dry air across the adsorbent to remove the adsorbed water. Detection and quantification limits were determined for a GC-FID system and compared to GC-MS. The applicability of the method was tested with a methanol eliminating silane modified polymeric adhesive (SMP-adhesive for parquet) in an emission test chamber
Volatile organic compounds (VOC) are ubiquitous in the indoor air, since they emit from materials used indoors. Investigations of these materials are mostly carried out in test chambers under controlled climatic conditions. Quality control of these test chamber measurements is important but there is a lack of commercially available homogenous reference materials. The approach of this study is to dope a supporting material with VOCs, which are then reproducibly released in measurable chamber air concentrations between 30 to 300 µg m ³. From several tested supporting materials vacuum grease (APIEZON M) was selected because of its very low own emissions. First tests were conducted with styrene. For the estimation of the initial emission and the emission over time FEM (finite element methods) modelling was used. Based on this, five samples with a surface of 7 cm2 and a thickness of 12 mm with a content of 1 ‰ styrene were investigated at (23 ± 2) °C and (50 ± 5) % relative humidity in the µ-chamber (3 samples) and 24 L test chambers (2 samples) for 28 days. Air samples were taken after 24 hours, 3, 7, 14, 21 and 28 days on Tenax TA® sorption tubes and analyzed by TD-GC-MS. The area specific emission rate (SERa) was calculated to compare the results from both chamber types. After 24 hours SERa was between 0.8 0.9 µg cm 2 h 1 (3800 4000 µg m 3) for the µ-chamber samples and between 0.9 1.1 µg cm 2 h 1 (300-370 µg m 3) for the 24 L test chamber samples. After 28 days the SERa was at 0.2 µg cm 2 h 1 for all samples. The relative standard deviation of the SERa was between 1 26 %. These results show the applicability of vacuum grease as supporting material and the favored starting concentration range could be achieved in the 24 L test chambers.
Volatile Organic Compounds (VOC) are ubiquitous in the indoor air since they are emitted from materials used indoors. Investigations of these materials are mostly carried out in emission test chambers under controlled climatic conditions. Reference materials are an important tool for quality assurance/Quality control of emission test chamber measurements but so far they are not commercially available. In this study, a new approach was tested to develop an appropriate reference material with homogenous and reproducible emission of the VOC with well measurable air concentrations in emission test Chambers larger than 20 L at air change rates of 0.5 - 1 /h.
Thermoplastic Polyurethane (TPU) was selected as Matrix material which was impregnated with 2,2,4- trimethyl-1,3-pentanediol monoisobutyrate (texanol) as test VOC using compressed carbon dioxide. An optimization of the impregnation parameters such as temperature, pressure, time, VOC injection volume and TPU sample size was performed until the targeted area specific Emission rate (SERa) value was reached. Further aspects like process control, storage effects and correlation of the sample size to the emission rate were investigated. It was found that the SERa immediately after sample preparation were not reproducible between the batches but became unified 10 days after loading into the test chamber indicating the necessity of aging before use. SERa between 13,000 and 18,000 mg m-2 h-1 were obtained, and the impregnated materials could be well stored in aluminum-coated polyethylene foil for at least seven weeks without significant losses. Furthermore, the impregnation of styrene and the SVOC 2,6-diisopropylnaphthalene was tested.
Recent research into emissions of (semi-)volatile organic compounds [(S)VOC] from solid materials has focused on the development of suitable reference materials for quality assurance/quality control of emission test chamber measurements, which fulfill requirements such as homogenous and reproducible (S)VOC release. The approach of this study was to find a method for preparation of a material with predictable (S)VOC emission rates. AVOC (styrene) and an SVOC (2,6-diisopropylnaphthalene, DIPN), loaded into either vacuum grease or a 1:1 mixture of paraffin/squalane, have been tested. For the prediction of the emission rates, a model using the finite element method (FEM) was created to simulate the (S)VOC emission profiles. Theoretical and experimental results obtained in a Micro-Chamber/Thermal Extractor (μ-CTE™) and in 24 L emission test chamber measurements were in good agreement. Further properties were investigated concerning the material applicability, such as shelf life and inter-laboratory comparability. The maximum relative standard deviation in the inter-laboratory study was found to be 20%.