• Journal of the Korean Vacuum Society
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• v.16 no.2
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• pp.99-104
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• 2007

Porous silicon exhibiting dual optical properties, both $Febry-P{\acute{e}}rot$ fringe (optical reflectivity) and photoluminescence had been developed and used as chemical sensors. Porous silicon samples were prepared by an electrochemical etch of p-type silicon wafer (boron-doped, <100> orientation, resistivity ; $1-10{\Omega}cm$). Two different types of porous silicon, fresh porous silicon (Si-H terminated) and oxidized porous silicon (Si-OH terminated)by the thermal oxidation, were prepared. Then the samples were exposed to the vapor of various organics, such as methanol, acetone, hexane, and toluene. Both reflectivity and photoluminescence were simultaneously measured under the exposure of organic vapors for sensing VOC's. These surface-modified samples showed unique respond in both reflectivity and photoluminescence with various organic vapors. While polar molecules exhibit greater quenching photoluminescence, molecules having higher vapor pressure show greater red shift for reflectivity.

• Analytical Science and Technology
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• v.27 no.4
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• pp.201-212
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• 2014

Polycyclic aromatic hydrocarbons (PAHs) that are carcinogenic and persistent will be restricted in consumer products from December 27, 2015 by EU REACH regulation. Pretreatment using Soxhlet extraction and quantitative analysis by GC-MS were studied to develop the method for analyzing 18 PAHs in consumer products as well as to detect the amounts and the kinds of PAHs in consumer products such as grips of a bag and a hammer, a cable and a plastic sandal. Linearity and precisions were evaluated by analyses of the standard PAH solutions ranging from 0.3125 mg/L to 5.00 mg of each of 18 PAHs. Linearity of resulting standard curves for all 18 PAHs were obtained with $R^2$ above 0.999. Precisions of the retention times and the peak areas were found to be 0.00%~0.05% and 1.16%~3.69% of relative standard deviations, respectively. The recoveries for spiked samples were all around 95%~105% after Soxhlet extration using three different solvents such as dichloromethane, hexane and toluene. The limits of quantitation for 18 PAHs in solutions and polymer samples by GC-MS were evaluated to be 0.327 mg/L (Benzo[ghi]perylene)~0.464 mg/L (Acenaphthylene) and 1.635 mg/kg (Benzo[ghi]perylene)~2.32 mg/kg (Acenaphthylene) based upon dilution factor of 5, respectively. Under the developed analytical method, only trace amounts of phenanthrene were detected in three samples while 15 kinds of PAHs including phenanthrene were detected in a grip of hammer with concentrations of maximum 83.4 mg/kg of Phenanthrene and minimum 8.5 mg/kg of Acenaphthylene. Further studies are needed to decrease the quantitation limit and to check the feasibility of decreasing Soxhlet time as well as to demonstrate cases that the clean up is required.

• Applied Chemistry for Engineering
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• v.3 no.1
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• pp.130-137
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• 1992

The Graft copolymerization of acrylonitrile(AN) and styrene(ST) onto chloroprene rubber(CR) were carried out with benzoyl peroxide(BPO) as an initiator. The synthesized graft copolymer(ACS) was separated from polymeric mixture by the extraction with ethyl acetate and n-hexane, acetone and methanol, dimethylformamide(DMF) and methanol mixed solvent systems. The graft copolymer obtained, acrylonitrile-chloroprene-styrene(ACS) was identified by IR spectrophotometer. The effect of mole ratio of styrene to acrylonitrile, reaction time and temperature, initiator concentration, CR content and solvents on graft copolymerization were examined. It was observed that the grafting efficiency increased with [ST]/[AN] mole ratio and reaction time. The grafting efficiency increased with increasing initiator concentration and CR content. The maximum grafting efficiency was obtained when the mole ratio of [ST]/[AN] was 1.5 and reaction was made at 40hrs, and $70^{\circ}C$ using chloroform/toluene mixed solvent. The thermal properties, light resistance and flammability of ACS were compared with those of ABS and AES. It was found that flame retardancy of related polymers increased in the order ACS>ABS>AES. The thermal stability of ACS was greatly improved when compared with ABS or AES. Morphology of ACS was also investigated by using a transmisson electron microscope(TEM).

• Applied Chemistry for Engineering
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• v.25 no.2
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• pp.174-180
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• 2014

A plasma hydrophobic coating on commercial fish feed was conducted to prolong the floating time of feed, thereby enhancing the feed consumption rate and reducing the contamination of water in fish farms. The hydrophobic coating on the fish feed was prepared using an atmospheric-pressure dielectric barrier discharge (DBD) plasma with hexamethyldisiloxane (HMDSO), toluene and n-hexane as the precursors. The effect of the parameters such as input power, precursor type and coating time on the coating performance were examined. The physicochemical properties of the coating layer were analyzed using a Fourier transform infrared (FTIR) spectrometer and a contact angle (CA) analyzer. The water CA increased after the coating preparation, indicating that the surface changed from hydrophilic to hydrophobic. The FTIR characterization revealed that the hydrophobic layer was comprised of functional groups such as $CH_3$, Si-O-Si and Si-C. As a result of the hydrophobic coating, the floating time of the fish feed increased from several seconds to 3 minutes, which suggested that the plasma coating method could be a viable means for practical applications. Compared to the water CA measured as soon as the coating layer was prepared, the 6-day aged sample exhibited a substantial CA increase, confirming the aging effect on the improvement of the hydrophobicity.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.6 no.2
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• pp.187-201
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• 1996

This study was to evaluate the efficiency of diffusive monitor using activated carbon fiber(ACF, KF-1500) in measuring airborne organic solvents. The following characteristics were identified and studied as critical to the performance of diffusive monitor; recovery, sampling rate, face velocity, reverse diffusion and storage stability. For the evaluation of the performance of this monitor, MIBK, PCE, toluene were used as organic solvents. In the sampling rate experiments, eight kinds of solvents (n-hexane, MEK, DIBK, MCF, TCE, CB, xylene, cumene) as well as the above solvents were used. The results were as follows: 1. The desorption efficiencies(DE's) of ACF diffusive monitor ranged from 83 % to 101 %. In contrast, those of coconut shell charcoal ranged from 78 % to 102 %. Especially, the DE's of ACF for the polar solvents such as MEK were superior to those of charcoal. 2. Experimental sampling rates on ACF were average 42ml/min(37-46ml/min) for 11 organic solvents at $24{\pm}2^{\circ}C$, $50{\pm}5%RH$. However ideal sampling rates(DA/L) were 33 % higher than experimental sampling rates. 3. The initial response(15~16 min) of the testing monitor was 2 times higher than the actual concentration determined by the reference methods at $24{\pm}2^{\circ}C$, $8{\pm}5%RH$ and $80{\pm}5%RH$. Within 1 hours, the curve reached a linear horizontal line at low humidity condition. But sampling efficiencies decreased with respect to time at high humidity condition. And sampling efficiencies were higher at high humidity condition than low humidity condition for MIBK. 4. At very low velocity (less than 0.02 m/sec), the concentration of ACF diffusive monitor were poorly estimated. But ACF diffusive monitor were not affected at higher velocity(0.2 m/sec-0.6 m/sec). 5. There was no significant reverse diffusion when the ACF monitors were exposed to clean air for 2 hours after being exposed for 2 hours at the level of 1 TLV. 6. There was no significant sample loss during 3 weeks of storage at room temperature and 5 weeks of storage at refrigeration.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.40 no.2
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• pp.203-214
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• 2014

We measured the contact dermatitis-causing substances concentrations in 28 commercial oxidative hair-coloring products. This study was aimed to provide the fundamental data about oxidative hair-coloring products. We selected 10 oxidation dyes (p-phenylenediamine, toluene-2,5-diamine, m-phenylenediamine, nitro-p-phenylenediamine, p-aminophenol, m-aminophenol, o-aminophenol, p-methylaminophenol, N,N'-bis(2-hydroxyethyl)-p-phenylenediamine sulfate, 2-methyl-5-hydroxyethylaminophenol) and 4 heavy metal (nikel; Ni, chromium; Cr, cobalt; Co, copper; Cu) as contact dermatitis-causing substances. To identify 10 oxidation dyes, hexane-2% sodium sulfite was used for the rapid and simple extraction and ultra performance liquid chromatography (UPLC) analysis was used for simultaneous analysis in 12 minutes. 10 oxidative dyes were detected as indicated on the product packaging and each concentration was lower than prescribed upper concentration limit by pharmaceutical manufacturing standards. And we analysed inductively coupled plasma-optical emission spectrophotometer (ICP-OES) for content search of heavy metal after microwave digestion. The heavy metal average concentration in oxidative hair-coloring products was 0.572 ${\mu}g/g$ for Ni, 3.161 ${\mu}g/g$ for Cr, 2.029 ${\mu}g/g$ for Co, 0.420 ${\mu}g/g$ for Cu, respectively. The average of concentration in powder type (henna) was higher than those of other foam and cream type oxidative hair-coloring products as follows; 1.800 ${\mu}g/g$ for Ni, 10.127 ${\mu}g/g$ for Cr, 7.082 ${\mu}g/g$ for Co, 1.451 ${\mu}g/g$ for Cu. Hair coloring products were classified into the six colors - black, dark brown, brown, dark brown, light brown, red brown and analyzed. Brown color had the highest average concentration of Co and the others had the highest average concentration of Cr.

• Korean Journal of Medicinal Crop Science
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• v.15 no.4
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• pp.296-303
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• 2007

Acer tegmentosum (Acereaceae) has been used a source of traditional medicines for the treatment of hepatic disorders in Korea. This research was conducted to determine biofunctional activities of A. tegmentosum stem extract and to identify its bioactive components. Methanolic extract from A. tegmentosum stem was partitioned by using organic solvents, including n-hexane, ethyl acetate, n-butanol, and water. Two compounds were isolated by using an ODS column chromatography from ethyl acetate soluble fraction shown to the strongest antioxidant activity ($RC_{50}=3.15\;{\mu}g/m{\ell}$) among the fractions. The isolated compounds were analyzed by $^1H$ and $^{13}C$ NMR, IR, UV/VIS, MS spectrum data and identified as catechin, ${\rho}-Hydroxyphenethyl$ alcohol $1-O-{\beta}-_D-(6'-O-galloyl)-glucopyranoside$. The compounds have shown strong antioxidant activity, with similar activity to BHA ($RC_{50}=2\;{\mu}g/m{\ell}$). Especially, ${\rho}-Hydroxyphenethyl$ alcohol 1-O-{\beta}-_D-(6'-O-galloyl)-glucopyranoside$ was shown strong anti-lipid peroxidative activity. However, the compounds were not shown antimicrobial activities. In antimicrobial activity assays, ethyl acetate soluble fraction was effective to bacterial inhibition, such as Escherichia coli and Klebsiella pneumonia, with minimum inhibitory concentrations in $125\;{\mu}g/m{\ell}$. Otherwise, antifungal activity against Candida albicans was shown in n-hexane soluble fraction exhibiting $63\;{\mu}g/m{\ell}$ of minimum inhibitory concentration. In anticomplementary activity assays, water soluble fraction was the most effective exhibiting 24% inhibitory activity.

• Analytical Science and Technology
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• v.25 no.3
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• pp.178-189
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• 2012

As phthalates classified as toxic to reproduction category 2 and endocrine disrupting chemicals were more strictly regulated as Substances of Very High Concern (SVHC) for authorization in under EU REACH and considered as priority substances in RoHS II, standardization of phthalate testing method is now being proposed in IEC 62321 of IEC TC 111 and the 2nd revision of KS M 1991 is also finished. In order to assist standardization activities related to phthalating testing, solvent extraction part of existing national standards were compared and verified. Recovery of DEHP (diethylhexyl phthalate) from PVC (polyvinyl chloride) by Soxhlet extraction increased in the order of methanol, toluene, dichloromethane and hexane from 46.9% to 95.3% as measured by GC-MS. Optimum extraction time was verified to be 6 hours using hexane. Recovery of DBP (dibutyl phthalate), BBP (butylbenzyl phthalate), and DEHP from different matrixes such as PVC, nitro cellulose, ABS (acrylonitrile butadiene styrene). and EPDM(ethylene propylene diene monomer) rubber were evaluated to be more than 90% up to 99%. The detection limits of phthalates in solvent extraction followed by GC-MS analysis were 0.08~0.3 ${\mu}g/mL$ in solution and 8~30 mg/Kg in polymeric samples. GC-MS analyses of phthalates were carried out using different solvent extraction based on the EN 14372, ASTM D 7083, Japanese test method (MHLW 0906-4) and KS M 1991, proving that equivalent recoveries ranging from 98%~99% were obtained. DBP and DEHP were detected in three consumer products such as a child toy, a power cable and manicure with the amount of 22~1,910 mg/kg.