• Bulletin of the Korean Chemical Society
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• 제34권3호
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• pp.922-926
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• 2013

3,3',4,4'-Tetrachlorobiphenyl (IUPAC PCB77) is one of seven indicative polychlorinated biphenyls (PCBs) in the surface sediments. The current study presents a novel polyclonal antibody for the determination of the PCB77 using indirect competitive enzyme-linked immunosorbent assay. Under optimum conditions, PCB77 was determined within the concentration range of 0.01-100 ${\mu}g\;L^{-1}$, with a detection limit of 0.057 ${\mu}g\;L^{-1}$. The assays were tested for their cross-reactivity profiles using 3 selected congeners and 4 Aroclor products. The assays were highly specific for coplanar PCB congeners, but less specific for Aroclor1248. The spiked recoveries from five sediment samples were 86%-114% for PCB77 from ELISA, which were satisfactory. The current study demonstrated that the developed antiserum and immunoassay procedure can be used to detect PCB77 in environmental samples. The results of the sediment analysis were confirmed by conventional GC/ECD.

• Bulletin of the Korean Chemical Society
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• 제32권9호
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• pp.3437-3442
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• 2011

An on-line flow injection analysis with dual pre-concentration method was developed to determine the ultra trace tri and hexavalent chromium in water. In this system, the cation and anion pre-concentration columns were combined with a 10-port injection valve and then used to separate and concentrate Cr (III) and Cr (VI) selectively. The two species of concentrated chromium were sequentially eluted and determined by using HCl-KCl buffer of pH 1.8 as an eluent. Cr (III) was oxidized by hydrogen peroxide to Cr (VI). It was detected spectrophotometrically at 548 nm by complexation with DPC (diphenylcarbazide). Several factors such as concentration of $H_2O_2$, DPC and coil length in reaction condition were optimized. The linear range for Cr (III) and Cr (VI) was 0.1-50 ${\mu}g$/L. The limit of detections ($3{\sigma}$) of Cr (III) and Cr (VI) were 52 ng/L and 44 ng/L under the optimized FIA system, and their recoveries 98% and 103%, respectively. This method was applied to analyze contamination level of chromium species in tap water, groundwater and bottled water.

• 한국연초학회지
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• 제28권2호
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• pp.152-157
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• 2006

A new procedure has been developed for the quantitation of aromatic amines in mainstream cigarette smoke. Two solid-phase extraction (SPE) clean up steps, using a different retention mechanisms, are required to process the samples. The first step used a cation-exchange cartridge, followed by a second step that used a cartridge with a hydrophobic retention character. The aromatic amines eluted from the second SPE cartridge are derivatized with pentafluoropropionic anhydride. This new method have advantages over other reported techniques, being sensitive, robust, and easily automated. The detection limits were ranged from 0.12 ng/mL for 1-aminonaphthalene to 0.16 ng/mL for 3-aminobiphenyl and the recoveries were from 97 to 106%. Compared with other reports for analysis of 2R4F reference cigarette, this method shows a close analytical data and good repeatability.

• 한국연초학회지
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• 제36권1호
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• pp.12-19
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• 2014

A matrix solid-phase dispersion (MSPD) method was developed for extracting and cleaning-up the selected agrochemicals in tobacco using gas chromatography-mass spectrometry with selected ion monitoring (GC/MS-SIM). Different parameters of the method were investigated and optimized, such as the type of solid-phase (alumina, $C_{18}$ and Florisil) and eluent (acetone, acetonitrile, ethylacetate and n-hexane). The best results were obtained using 0.5 g of tobacco sample, 1.0 g of $C_{18}$ as dispersant sorbent, 1.0 g of Florisil as clean-up sorbent and acetonitile saturated with n-hexane as eluting solvent. The method was validated using tobacco samples fortified with agrochemicals at their different concentration levels. This method gave good linearity for the selected agrochemicals of ranging from $0.01{\mu}g/mL$ to $0.1{\mu}g/mL$. Recoveries of the selected agrochemicals in tobacco were more than 80 % and reproducibilities were found to be better than 10 % RSD. Those results suggested that the analytical procedure including MSPD method in combining with GC/MS could be applicable to the rapid determination often the selected agrochemicals in tobacco.

• 한국환경보건학회지
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• 제31권1호
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• pp.73-78
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• 2005

A determination method of trace Ni(II) and Zn(II) in aqueous solution was studied and developed by adsorbing on titanium dioxide. For this purpose, several conditions were optimized such as the pH of sample solution, adsorption time, the types and concentration acid, and desorption time. The titanium dioxide was added in sample solution which was pH adjusted. Then, the sample solution was stirred for 5 minutes. This mixture was stored in room temperature for 30 minutes to allow adsorption. After filtering and washing the titanium dioxide, the analytes were dissolved from the titanium dioxide on membrane filter by an ultrasonic vibration for 10 minutes in 1.0 M $HNO_3$ solution. Then, this sample solution was analysed using ICP-AES. The adsorption equilibrium was achieved in 30 minutes. The desorption was the most of effective with 1.0 M(mol/l) nitric acid solution, and desorption time was 10 minutes. This procedure was applied for the analysis of two real samples, i.e., brown seaweed and tangle. The recoveries of Ni(II) and Zn(II) in spiked samples were 89.4${\sim}$98.9% for analytes.

• Preventive Nutrition and Food Science
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• 제14권3호
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• pp.260-264
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• 2009

A high-performance liquid chromatography method was applied to determine the contents of tocopherols in edible oils using a LiChrosorb DIOL HPLC column and hexane fortified with 0.1% acetic acid in an isocratic mode. The validation of the method included tests for linearity, sensitivity, accuracy, precision, and recovery. All calibration curves showed good linear regression ($r^2$>0.9995) within the tested ranges. The established method offered good precision and accuracy with overall intra-day and inter-day variations of 0.94$\sim$4.27 and 1.77$\sim$ 4.88%, respectively. The tocopherol recoveries ranged from 91.44$\sim$108.90%. Subsequently, the method was successfully applied to qualitatively and quantitatively determine the total contents of $\alpha$, $\gamma$, and $\delta$-tocopherols in 12 selected refined edible oils, showing a range of 0.92 to 188.71 mg/100 g.

• 대한화학회지
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• 제31권5호
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• pp.425-433
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• 1987

모세관 컬럼을 사용한 기체크로마토그래피로 19종 유기염소제 농약의 분리를 검토하였고, 쌀에 첨가한 농약들의 회수율을 구하여 봄으로써 실제분석에 대한 본 방법의 응용 가능성을 조사하였다. SE-30과 OV-17모세관 컬럼의 분리를 비교하여 본 결과 OV-17 컬럼(25m ${\times}$ 0.20mm, 0.27${\mu}$m 두께)으로 분리가 잘되고 있으며, splitless방식으로 주입한 농약들의 머무른 시간과 봉우리 면적에 대한 상대표준 편차가 최대로 0.16%와 8.2%이었다. 쌀에 첨가된 농약의 회수율은 대부분 85%이상이었고 분석 결과에 대한 상대표준편차가 가장 큰 것이 11.4%로서 흔적량의 잔류농약분석에서 비교적 정밀도가 좋음을 확인하였다.

• 제어로봇시스템학회논문지
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• 제14권12호
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• pp.1302-1312
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• 2008

Relaxed Static Stability(RSS) has been applied to improve flight performance of modern version supersonic jet fighters. Flight control systems are necessary to stabilize an unstable aircraft and to provide adequate handling qualities. Also, flight control systems of modern aircraft employ many safety measure to cope with emergency situations such as a pilot unknown attitude flight conditions of an aircraft in night flight-testing. This situation is dangerous because the aircraft can lose if the pilot not take recognizance of situation. The system called the "Pilot Activated Recovery System" or PARS, provided a pilot initiated automatic maneuver capable of an aircraft recoveries in situations of unusual attitudes, speed and altitude. This paper addresses the concept of PARS with AARS(Automatic Attitude Recovery System), ATCS(Automatic Thrust Control System) and MARES(Minimum Altitude Recovery Estimation System), and this control law is designed by nonlinear control law design process based on model of supersonic jet trainer. And, this control law is verified by real-time pilot evaluation using an HQS(Handling Quality Simulator). The result of evaluation reveals that the these systems support recovery of an aircraft unusual attitude and speed, and improve a safety of an aircraft.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 The 6th International Symposium of East Asian Resources Recycling Technology
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• pp.193-197
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• 2001

This study was carried out to recover gold, silver and other valuable metals from the printed circuit boards (PCB) of waste computers. PCB samples were crushed to under 1mm by a shredder and initially separated into 30% conducting and 70% non-conducting materials by an electrostatic separator. The conducting materials, which contained the valuable metals, were then used as the feed material for magnetic separation where it was found that 42% was magnetic and 58% non- magnetic. The non-magnetic materials contained 0.227mg/g Au and 0.697mg/g Ag. Further leaching of the non-magnetic component using 2.0M sulfuric acid and 0.2M hydrogen peroxide at 85$^{\circ}C$ extracted more than 95% copper, iron, zinc, nickel and aluminium. Au and Ag were not extracted in this solution, however, more than 95% of Au and 100% of Ag were selectively leached with a mixed solvent (0.2M ammonium thiosulfate, 0.02M copper sulfate, 0.4M ammonium hydroxide). Finally, the residues were reacted with a NaCl solution to leach out Pb while sulfuric acid was used to leach out Sn. Recoveries reached 95% and 98% in solution, respectively.

• Bulletin of the Korean Chemical Society
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• 제35권7호
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• pp.2072-2076
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• 2014

Sub-micrometer size gold particles were electrodeposited on a transparent fluorine-doped tin oxide (FTO) from acetonitrile solution containing $AuCl_4{^-}$ and tetramethylammonium tetraflouroborate (TMATFB) for detecting $NO_2{^-}$. A series of two-electron ($2e^-$) and one-electron ($1e^-$) reductions of the $AuCl_4{^-}-AuCl_2{^-}-Au$ redox systems were observed at FTO and a highly stable and homogeneous distribution of Au on FTO (Au/FTO) was obtained by stepping the potential from 0 to -0.55 V (vs. Ag/$Ag^+$). The Au/FTO electrode exhibited sufficiently high catalytic activity toward the oxidation of $NO_2{^-}$ with a detection limit (S/N = 3) and sensitivity of 2.95 ${\mu}M$ and 223.4 ${\mu}A{\cdot}cm^{-2}{\cdot}mM^{-1}$, respectively, under optimal conditions. It exhibited an interference-free signal for $NO_2{^-}$ detection with excellent recoveries from real samples.