• Bulletin of the Korean Chemical Society
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• 제30권11호
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• pp.2669-2674
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• 2009

Controlled reduction of silver alkylcarbamate complexes with hydrogen gas was investigated as a facile synthetic method for high concentrations of silver nanocolloids in organic solvent. Polyvinylpyrrolidone (PVP) was used to stabilize the silver colloids obtained from the chemical reduction. To determine optimum conditions for preparation of the stable and controlled silver colloids with the narrowest particle size and distribution, a large number of experiments were carried out involving variations in the concentrations of the silver 2-ethylhexylcarbamate (Ag-EHCB) complex, PVP, and 2-propanol. The initial colloid had a mean particle diameter between 5$\sim$50 nm, as measured by transmission electron microscopy, and exhibited a sharp absorption band in the UV region with a maximum size near 420 nm. After treatment with a reducing agent, the colloids were characterized by ultraviolet-visible spectroscopy, X-ray diffraction, and high-resolution transmission electron microscopy.

• 한국환경농학회지
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• 제30권4호
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• pp.432-439
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• 2011

BACKGROUND: An official analytical method was developed to determine etofenprox residues in agricultural commodities using high-performance liquid chromatography (HPLC). METHODS AND RESULTS: The etofenprox residue was extracted with acetone from representative samples of five raw products which comprised rice grain, apple, mandarin, cabbage, and soybean. The extract was then serially purified by liquid-liquid partition and Florisil column chromatography. For rice and soybean samples, acetonitrile/n-hexane partition was additionally coupled to remove nonpolar lipids. Reversed phase HPLC using an octadecylsilyl column was successfully applied to separate etofenprox from co-extractives. Intact etofenprox was sensitively detected by ultraviolet absorption at 225 nm. Recovery experiment at the quantitation limit validated that the proposed method could apparently determine the etofenprox residue at 0.02 mg/kg. Mean recoveries from five crop samples fortified at three levels in triplicate were in the range of 93.6~106.4%. Relative standard deviations of the analytical method were all less than 10%, irrespective of crop types. A selected-ion monitoring LC/mass spectrometry with positive atmospheric-pressure chemical ionization was also provided to confirm the suspected residue. CONCLUSION(s): The proposed method is simple, rapid and sensitive enough to be employed in routine inspection or monitoring of agricultural products for the etofenprox residue.

• Journal of Pharmaceutical Investigation
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• 제39권3호
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• pp.177-183
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• 2009

A rapid and sensitive reversed-phase high performance liquid chromatography (HPLC) method was developed for the determination of piroxicam in the rabbit plasma. After a treatment of plasma sample by liquid-liquid extraction, the drug was analyzed on an HPLC system with ultraviolet detection at 330 nm. HPLC was carried out using reversed-phase isocratic elution with a C18 column, a mobile phase of a mixture of acetonitril, doubly deionized water and acetic acid 43.74:56.00:0.26 v/v%) at a flow rate of 1.1 mL/min. The chromatograms showed good resolution and sensitivity and no interference of plasma. The calibration curve for the drug in plasma sample was linear over the concentration range of 0.01-2.0 ${\mu}$g/mL. The intra- and inter-day assay accuracies of this method ranged from 86.82% to 108.33% of normal values and the precision did not exceed 13% of relative standard deviation. The plasma concentration of piroxicam decreased to below the quantifiable limit at 12 hr after the i.v. bolus administration to rabbits following dose of 0.375 mg/kg yielding a apparen t plasma half life of 1.38 hr. The transdermal route prolongs plasma levels of piroxicam. The bioavailability, calculated from the dose-adjusted ratio of the $AUC_{transdermal}$ to the $AUC_{i.v.}$, was 7.44%. The plasma concentration of piroxicam was detected by 48 hr after the transdermal administration of patch at a dose of 32 mg/kg. This method was suitable for cutaneous absorption studies of piroxicam in the rabbit after transdermal administration of different types of dosages of the drug.

• Applied Biological Chemistry
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• 제41권8호
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• pp.595-599
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• 1998

An analytical method was developed to determine tricyclazole residues in rice grain, straw, and soil using high-performance liquid chromatography (HPLC) with ultraviolet absorption detection. Tricyclazole was extracted with methanol from moist rice grain, straw, and soil samples. n-Hexane washing was employed to remove nonpolar co-extractives during liquid-liquid partition. Tricyclazole was then extracted with dichloromethane from alkaline aqueous phase, while acidic interferences remained in the phase. Dichloromethane extract was further purified by silica gel column chromatography prior to HPLC determination. Reverse-phase HPLC using an octadecylsilyl column was successfully applied to separate and quantitate the tricyclazole residue in sample extracts monitored at ${\lambda}_{max}$ 225nm. Recoveries from fortified samples averaged $95.5{\pm}3.0%\;(n=6),\;87.5{\pm}20.%\;(n=6),\;and\;84.3{\pm}2.8%$ (n=12) for rice grain, straw, and soil, respectively. Detection limit of the method was 0.02 mg/kg for rice grain and soil samples while 0.05 mg/kg for rice straw samples. The proposed method was reproducible and sensitive enough to evaluate the safety of tricyclazole residues in rice grain, straw, and soil.

• 한국환경농학회지
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• 제29권3호
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• pp.247-256
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• 2010

A high-performance liquid chromatographic (HPLC) method was developed to determine buprofezin residues in hulled rice and fruits. The buprofezin residue was extracted with acetone and the extract was stepwise purified by liquid-liquid partition and Florisil column chromatography. For rice samples, acetonitrile/n-hexane partition was additionally employed to remove nonpolar lipids. Reversed phase HPLC using an octadecylsilyl column was successfully applied to separate buprofezin from sample co-extractives, as detected by ultraviolet absorption at 250 nm. Recovery experiment at the limit of quantitation validated that the proposed method could evidently determine the buprofezin residue at the level of 0.02 mg/kg. Mean recoveries from hulled rice, apple, pear, and persimmon samples fortified at three tenfold levels were in the range of 80.8~85.2%, 89.1~98.4%, 88.8~95.7% and 90.8~96.2%, respectively. Relative standard deviations of the analytical method were all less than 5%, irrespective of sample types. A selected-ion monitoring LC/mass spectrometry with positive electrospray ionization was also provided to sensitively confirm the suspected residue.

• Corrosion Science and Technology
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• 제19권1호
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• pp.16-22
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• 2020

It is important to realize that benzoate was intercalated into hydrotalcite (HTC-Bz) by the co-precipitation method. In this case, acrylic coating with 0.5 wt% HTC-Bz was deposited on carbon steel using the spin coating method. Next, the HTC-Bz structure was characterized by Field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR). In fact, an ultraviolet vision spectroscopy (UV-Vis) was used to determine the benzoate content in HTC-Bz, and the UV absorption ability of HTC-Bz. Using electrochemical techniques, water contact angle measurement, and thermal-gravimetric analysis, we compared the protective properties before and after QUV test, hydrophobicity and the thermal stability of acrylic coating containing HTC-Bz. The obtained results showed that HTC-Bz with a plate-like structure was successfully synthesized; benzoate was intercalated into the interlayer of hydrotalcite with a concentration of 28 wt%. Additionally, it was noted that HTC-Bz has an UV absorption peak at 225 nm. In conclusion, the addition of HTC-Bz enhanced the UV stability, hydrophobicity and the thermal stability of acrylic coating.

• 한국토양비료학회지
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• 제16권4호
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• pp.347-352
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• 1983

한국산(韓國産) 이탄(泥炭), 화산회토(火山灰土) 및 무기질(無機質) 답토양(畓土壤)에 유기물(有機物)에 대(對)한 일련의 토양화학적성상(土壤化學的性狀)의 비교연구(比較硏究)로부터 본(本) 실험(實驗)은 김포(金浦), 평택(平澤), 김제(金堤) 및 영동(永同)의 이탄(泥炭)과 제주도(濟州島) 화산회토(火山灰土) 그리고 수원(水原)의 답토양(畓土壤)으로부터 각각(各各) 부식물(腐植物)을 유출(油出)하고 Hymatomelanic acid와 Humic acid로 분획(分劃)하여 가시(可視), UV 및 IR 광역(光域)에서 흡수(吸收) Spectra를 측정(測定)하여 비교(比較)하여 보았다. Humic acid와 Hymatomelanic acid는 UV 및 가시광역(可視光域)에서 극대(極大)나 극소(極小)의 Peak를 가지지 않으며 파장(波長)의 감소에 따라 단조로운 Optical density의 증가를 보이는 Spectra를 나타내었다. 또한 이탄(泥炭) 및 화산회토(火山灰土)와 답토양(畓土壤) 부식물간(腐植物間)의 흡수(吸收) Spectra는 이 범위의 광파장역(光波長域)에서 별다른 상이성(相異性)이 없었으나 화산회토(火山灰土), 이탄(泥炭), 무기질(無機質) 답토양(畓土壤)의 순(順)으로 완만(緩慢)한 경사(傾斜)를 이루었다. Humic acid와 Hymatomelanic acid의 IR spectrum의 주요한 흡수대(吸收帶)는 $3400cm^{-1}$, $2900cm^{-1}$, $1720cm^{-1}$, $1625cm^{-1}$, $1400-1450cm^{-1}$, $1200-1250cm^{-1}$, $1050cm^{-1}$ 등이며 토양형간(土壤型間)의 상이점(相異點)은 미미(微微)하나 Hymatomelanic acid는 파수(波數) $2900cm^{-1}$에서 흡수(吸收) peak를 가지며 파수(波數) $1720cm^{-1}$ 부근에서의 흡수(吸收)가 $1625cm^{-1}$ 부근보다 큰 반면에 Humic acid는 $1625cm^{-1}$ 부근이 $1720cm^{-1}$ 부근보다 큰 흡수(吸收) band를 이루었다. Humic acid의 관능기(官能基)의 함량(含量)은 공시(供試)된 토양형(土壤型) 사이에 큰 차이(差異)가 없었으나 화산회토(火山灰土), 이탄(泥炭), 무기질(無機質) 답토양(畓土壤)의 순(順)으로 전산도(全酸度)가 낮았고 Carboxyl기(基)의 함량(含量)이 적었다.

• 한국전기전자재료학회논문지
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• 제21권9호
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• pp.818-824
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• 2008

The Separated Pulsed Laser Deposition (SPLD) technique uses two chambers that are separated by a conic metallic wall with a central orifice. The pressures of ablation chamber and deposition chamber were controlled by the differential vacuum system. We deposited zinc oxide (ZnO) thin films by SPLD method to obtain high quality thin films. When the bias voltage of +500 V was applied between a substrate and an orifice, the ZnO thin film was deposited efficiently. The deposited ZnO thin film at ablation chamber gas pressure of Ar 5 mTorr showed the sharpest ultraviolet absorption edge indicatory the band gap of about 3.1 eV. ZnO thin films were deposited using effect of electric and magnetic fields in the SPLD method. E${\times}$B drift happened by an electric fields and a magnetic fields, activated plasma plume, as a result the film surface became very smooth. When the bias voltage of +500 V and magnet of 0,1 T were applied the ZnO thin films surface state showed high quality. Grain size was 41.99 nm and RMS was 0.84 nm.

• Electronic Materials Letters
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• 제14권6호
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• pp.739-748
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• 2018

ZnS nanowalls, microspheres and rice-shaped nanoparticles have been successfully grown on graphene oxide (GO) sheets by the hydrothermal method. The morphologies, structures, chemical compositions and optical properties of the as-synthesized GO/ZnS have been characterized by X-ray power diffraction, energy dispersive spectrometer, scanning electron microscope, Raman spectra, photoluminescence spectroscopy and ultraviolet-visible absorption spectroscopy. It was found that the concentration of CTAB and the reaction temperature were important in the formation of GO/ZnS microstructures. The photocatalytic activity of the as-synthesized GO/ZnS was investigated through the photocatalytic degradation of textile dyeing waste. Results showed that the catalytic activity of the GO/ZnS porous spheres to methyl orange and methylene blue is higher than those of other samples. The degradation rates of methyl orange and methylene blue by porous spheres in 50 min were 97.6 and 97.1%, respectively. This is mainly attributed to the large specific surface area of GO/ZnS porous spheres and high separation efficiency between photogenerated electron and hole pairs.

• 대한화장품학회지
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• 제31권3호
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• pp.245-251
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• 2005

화장품은 의약품과 달리 남녀노소를 불문하고 거의 평생에 걸쳐 사용하는 제품이므로 피부 및 인체의 안전성 확보는 중요한 문제라고 할 수 있다. 화장품의 안전성 평가는 화장품법에 식품의약품안전청장이 고시하도록 되어있어 현재 식약청고시 '기능성화장품등의 심사에 관한 규정'에서 정하고 있다. 자외선에 의한 피부독성은 피부노화, 피부홍반, 피부손상, 피부암 유발 면역계장애 등이 있으며, IARC (International agency for research on cancer)에서는 자외선을 사람에게 암을 유발하는 물질로 분류하고 있다. 자외선 노출에 의하여 설치류에 대한 피부암 유발보고는 많이 있고, 현재 전 세계적으로 자외선에 의한 피부 암화 과정에 대하여 활발한 연구가 진행되고 있다. 화장품이 광에 의한 영향을 평가하는 시험은 광독성시험으로, 국내에서 광독성에 대한 규정은 자외선에서 흡수가 없음을 증명하는 흡광도 시험자료를 제출하는 경우는 면제이고 그 외의 경우는 상기 고시에 의한 광독성 시험과 광감작성 시험을 실시하도록 되어 있다. 이 시험은 일반적으로 기니픽 또는 토끼를 포함한 적절한 동물로 실시하도록 규정되어 있다. 화장품 안전성 평가에 있어서 동물대체시험법의 요구는 3R (replacement, refinement, reduction) 운동으로 유럽을 중심으로 시작하여 이제는 전세계로 확대되어 있으며, 화장품 안전성심사에 있어 중요한 이슈로 대두되고 있다 화장품의 광독성 평가에 대한 대체시험법으로 3T3 NRU(neutral red uptake) 광독성시험이 2004년 4월 OECD 독성시험 기준으로 채택되었다. In vitro 광독성 시험법은 마우스 유래의 섬유아세포인 3T3 cell을 이용하여 광조사한 것과 광조사하지 않은 세포와의 세포독성을 NRU 시험을 이용하여 그 정도를 비교하여 그 차이(PIF, photoirritation factor)가 5배 이상이 되면 광독성 물질로 분류하는 평가방법이다.