• 한국대기환경학회지
• /
• 제30권4호
• /
• pp.362-377
• /
• 2014

Polycyclic aromatic hydrocarbons (PAHs) have been of particular concern since they are present both in the vapor and particulate phases in ambient air. In this study, a simple method was applied to determine the vapor phase PAHs, and the performance of the new method was evaluated with a conventional method. The simple method was based on adsorption sampling and thermal desorption with GC/MS analysis, which is generally applied to the determination of volatile organic compounds (VOCs) in the air. A combination of Carbotrap (300 mg) and Carbotrap-C (100 mg) sorbents was used as the adsorbent. Target compounds included two rings PAHs such as naphthalene, acenaphthylene, and acenaphthene. Among them, naphthalene was listed as one of the main HAPs together with a number of VOCs in petroleum refining industries in the USA. For comparison purposes, a method based on adsorption sampling and solvent extraction with GC/MS analysis was adopted, which is in principle same as the NIOSH 5515 method. The performance of the adsorption sampling and thermal desorption method was evaluated with respect to repeatabilities, detection limits, linearities, and storage stabilities for target compounds. The analytical repeatabilities of standard samples are all within 20%. Lower detection limits was estimated to be less than 0.1 ppbv. In the results from comparison studies between two methods for real air samples. Although the correlation coefficients were more than 0.9, a systematic difference between the two groups was revealed by the paired t-test (${\alpha}$=0.05). Concentrations of two-rings PAHs determined by adsorption and thermal desorption method consistently higher than those by solvent extraction method. The difference was caused by not only the poor sampling efficiencies of XAD-2 for target PAHs and but also sample losses during the solvent extraction and concentration procedure. This implies that the levels of lower molecular PAHs tend to be underestimated when determined by a conventional PAH method utilizing XAD-2 (and/or PUF) sampling and solvent extraction method. The adsorption sampling and thermal desorption with GC analysis is very simple, rapid, and reliable for lower-molecular weight PAHs. In addition, the method can be used for the measurement of VOCs in the air simultaneously. Therefore, we recommend that the determination of naphthalene, the most volatile PAH, will be better when it is measured by a VOC method instead of a conventional PAH method from a viewpoint of accuracy.

• 한국식품위생안전성학회지
• /
• 제3권4호
• /
• pp.193-202
• /
• 1988

농작물중 농약 잔류량조사 계획의 일환으로 전국주요시설 재배지에서 채취한 딸기와 오이 각 50점과 서울시 소재 5개 슈퍼마켓에서 시판되는 딸기를 수집, 농약 잔류량을 조사하였다. 딸기에서는 일부 시료에서 procymidone, chlorothalonil. captan, diazinon, ${\alpha}-endosulfan$ 등이 미량으로 검출되었으나 조사최대치의 경우에도 잔류허용기준의 1/79~1/2 에 불과하였다. Malathion, Fenitrothion, parthion 등 유기인계 살충제는 전시료에서 불검출되었으며 시판 딸기에서도 이와 비슷한 경향이었다. 오이에서는 유기인계 살충제가 전시료에서 불검출되었으며 기타 살균제의 검출빈도는 딸기와 비슷하였으나 잔류수준은 다소 낮은 경향이었다. 딸기와 오이 중 검출 빈도와 잔류수준이 비교적 높았던 농약은 procymidone과 chlorothalonil로서 이들의 조사최대치도 잔류허용기준에 크게 미달되고 있어 현재로서는 별 문제가 없는 것으로 판단되고 있다. 수일에 의한 딸기중 잔류농약의 경감효과는 38~95%로서 상당부분이 제거 되었다. 딸기 잿빛 곰팡이병 방제약으로 현재 많이 사용되고 있는 procymidone이나 dichloflanid에 대한 농약잔류향조사는 국내에서는 처음으로 시도되었으며, 아울러 본 조사연구는 금후 이들 농약에 대한 잔류허용기준설정에 기초자료가 될 것이다.

• Nuclear Engineering and Technology
• /
• 제51권4호
• /
• pp.1176-1179
• /
• 2019

Measurements of activity concentrations of radionuclides in atmospheric releases were performed in 2017-2018 at vent stacks of seven Russian nuclear power plants. The selected instruments and research methods, with detection limits significantly lower than the existing detection limit of Russian NPPs routine control, allowed to reliably determine up to 26 radionuclides. Analysis of experimental data allows to determine the list of radionuclides for calculation the effective dose rates to public and the permissible annual discharge levels for each Russian NPP. Radiocarbon is determined as major contributor for the dose from the atmospheric releases of LWGR reactors - up to 98% for EGP-6 and RBMK-1000 (Smolensk NPP) reactors. For PWR reactors (VVER) radionuclides contribution to the annual dose from atmospheric releases is more complicated, but, in general, dose is formed by tritium, $^{14}C$ and noble gases. The special monitoring results with ranking of measured radionuclides according to their contribution to the effective dose makes it possible to optimize the list of controlled radionuclides in airborne releases of Russian NPPs from 94 to 8-16 for different NPPs.

• 한국대기환경학회지
• /
• 제12권2호
• /
• pp.199-209
• /
• 1996

The purpose of this study is to evaluate analytical method for the measurement of carbonyl compounds and to apply method to the measurement of indoor and outdoor concentrations of these compounds at public facilities. For sampling, 2.4-dinitrophenylhydrazine (DNPH) coated DNPH-Silica cartridges were uwed in this study. DNPH reacts with carbonyl compounds and forms carbonyl hydrazone, The carbonyl hydarzone was eluted from the cartridge with acetonitrile and analyzed by reverse-phase HPLC with UV detection. Possible interference caused by ozone during sampling was eliminated by using KI trap commected in series with the DNPH-Silica cartridge. A number of experimental studies were undertaken to evaluate and validate the analytical method, including collection efficiency, recovery, repeatability, lower limits of detection, and effect of ozone. Indoor and outdoor measurements of carbonyl compounds were simultaneously carried out at 14 public facilities located in Taegu city and Kyungsan city from June to July, 1995. Except for one or two sites, the indoor concentrations were found to be higher than the outdoor concentrations for carbonyl compounds. And the concentrations of carbonyl compounds measured in the morning and afternoon were showed higher than the concentrations measured in the evening.

• 생약학회지
• /
• 제35권4호통권139호
• /
• pp.276-282
• /
• 2004

This study has been conducted to investigate the amount of residual sulfur dioxide for herbal medicines of 30 species which are purchased in 13 different regions (Bonghwa, Busan, Chunju, Jecheun, Kwangiu, Keumsan, Seoul, Taeku, Cheungdu, Xian, Beijing, Tokyo and Osaka). The sulfur dioxide residues were determined in the collected 386 samples by the modified Monier-Williams method. The residues of sulfur dioxide in 386 samples ranged from ND (under detection limit) to 2808 ppm. The sulfur dioxide in Cassiae Semon, Cinnamomi Ramulus, Cervi Cornu, Hoelen, Crataegi Fructus, Artemisiae Argyi Herba, Scolopendrae Corpus, Schizandrae Fructus and Cyperi Rhizoma were detected under the detection limit regardless of the collected regions. The sulfur dioxide residues in herbal medicines collected in domestic regions were relatively lower than those in foreign regions. There are no standards for sulfur dioxide residual limits of herbal medicines in Korea. This results will provide the scientific basis for the standardization of sulfur dioxide residues in Korea Pharmacopoeia.

• Journal of Korean Society for Atmospheric Environment
• /
• 제10권E호
• /
• pp.299-302
• /
• 1994

At a nuclear power plant, environmental radioactivity monitoring is routine work for the radiation safety management For the environmental monitoring of tritium($^3$H) activity in water sampled liquid scintillation counting( LSC) method is applied to measure low- energy beta activity from tritium in the samples. The $^3$H activity is measured using the BECKMAN 5801 system at the KRISS( Korea Research Institute of Standards and Science) for evaluating the lower limits of detection( LLD) of $^3$H measurement and the measuring capability of low-level $^3$H activity at four nuclear Power Plant sites. The LSC systems used for low-level $^3$H activity measurements at the nuclear Power Plants are confirmed to satisfy throughout an intercomparison study under the experimental arrangements by the KRISS.

• 천문학회지
• /
• 제46권2호
• /
• pp.65-74
• /
• 2013

We probe the feasibility of high-frequency radio observations of very rapid flux variations in compact active galactic nuclei (AGN). Our study assumes observations at 230GHz with a small 6-meter class observatory, using the SNU Radio Astronomical Observatory (SRAO) as an example. We find that 33 radio-bright sources are observable with signal-to-noise ratios larger than ten. We derive statistical detection limits via exhaustive Monte Carlo simulations assuming (a) periodic, and (b) episodic flaring flux variations on time-scales as small as tens of minutes. We conclude that a wide range of flux variations is observable. This makes high-frequency radio observations-even with small observatories-a powerful probe of AGN intra-day variability; especially, those which complement observations at lower radio frequencies with larger observatories like the Korean VLBI Network (KVN).

• 천문학회보
• /
• 제38권1호
• /
• pp.44.2-44.2
• /
• 2013

We probe the feasibility of high-frequency radio observations of very rapid flux variations in compact active galactic nuclei (AGN). Our study assumes observations at 230 GHz with a small 6-meter class observatory, using the SNU Radio Astronomical Observatory (SRAO) as example. We find that 33 radio-bright sources are observable with signal-to-noise ratios larger than ten. We derive statistical detection limits via exhaustive Monte Carlo simulations assuming (a) periodic, and (b) episodic flaring flux variations on time-scales as small as tens of minutes. We conclude that a wide range of flux variations is observable. This makes high-frequency radio observations - even with small observatories - a powerful probe of AGN intra-day variability; especially, those observations complement observations at lower radio frequencies with larger observatories like the Korean VLBI Network (KVN).

• Archives of Pharmacal Research
• /
• 제19권5호
• /
• pp.396-399
• /
• 1996

High-performance liquid chromatographic method with UV detecction was developed for the determination of theophylline and its metabolites in human urine using ${beta}$-hydroxyethyl theophylline$({beta} -HET)$ as an internal standard. For extraction of urine sample, quality control sample and xanthine-free blank urine were mixed with decylamine (ion-paring reagent) and ${beta}$-HET. After saturation with ammonium sulfate, the mixture was then extracted with organic solvent at pH values of 4.0-4.5. All separations were performed with ion-pair chromatography using decylamine as an ion-pairing reagent and 3mM sodium acetate buffered mobile phase (pH 4.0) containing 1% (v/v) acetonitrile and 0.75 mM decylamine. The detection limits of theophylline, 1, 3-DMU, 1-MU, 3-MX and 1-MX in human urine were 0.17, 0.17, 0.39, 0.19 and 0.19 ${\mu}g$/ml, based on a signal-to-noise ratios of 3.0. The mean intraday coefficients of variation (C.V.s) of each compound on nine replicates were lower than 2.0%, while mean interday C.V.s on three days were lower than 1.6%. All separations were finished within 40miutes.

• Bulletin of the Korean Chemical Society
• /
• 제24권1호
• /
• pp.37-44
• /
• 2003

We examined the effect of polyether-type nonionic surfactants (Brij 35, Triton X-100, Tween 20 and Tween 80) on the potentiometric properties of sodium-, potassium- and calcium-selective membranes which are prepared with widely used ionophores and four kinds of polymer matrices [poly(vinyl chloride) (PVC), polyurethane (PU), PVC/PU blend, and silicone rubber (SR)]. It was found that the PVC-based membranes, which provide the best performance among all other matrix-based membranes in the absence of nonionic surfactants, exhibited larger change in their potentiometric properties when nonionic surfactants are added to the sample solution. On the other hand, the sodium-selective SR-based membrane with calix[4]arene, potassium-selective PVC/PU- or SR-based membrane with valinomycin, and the calcium-selective SR-based membrane with ETH 1001 provide almost identical analytical performance in the presence and absence of Tween 20 or Tween 80 surfactants. The origin of nonionic surfactants effect was also investigated by interpreting the experimental results obtained with various matrices and ionophores. The results suggest that the nonionic surfactant extracted into the membrane phase unselectively form complexes with the primary and interfering ions, resulting in increased background potential and lower binding ability for the ionophore. Such effects should result in deteriorated detection limits, reduced response slopes and lower selectivity for the primary ions.