• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.2
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• pp.381-385
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• 2004

This study was conducted to develop an HPLC method for determining pantothenic acid in fortified foods which has typically been determined by microbiological assay (MBA) according to AOAC and Korean Food Code approved methods. Pantothenic acid was determined by reversed-phase ion-pair HPLC using UV absorption (200 nm) after extraction with 20 mM potassium phosphate solution by sonication. The recovery of spiked samples and detection limit (LOD) by HPLC were 83.5∼109.6% and 0.5 ppm (mg/kg), respectively. The LOD of the microbiological assay (MBA) was much lower than that of HPLC. The concentrations of pantothenic acid analyzed in all tested samples (n=13) confirmed compliance with declared label claims. The range of recovery ratio by the HPLC method when compared to the microbiological assay was 91.9∼117.6%. There was not significant difference (p<0.01) between the HPLC and MBA methods and the equation of the regression curve was y=1.1428x-0.2269 (r=0.9842). This proposed HPLC method for determining pantothenic acid appears to be suitable for determining pantothenic acid concentrations above 0.25 mg/100 g in fortified foods.

• Analytical Science and Technology
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• v.25 no.6
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• pp.460-466
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• 2012

An environmentally friendly, so-called green, high performance liquid chromatography method was developed and validated for the determination of trans, trans-muconic acid (t,t-MA) in human urine as a biomarker of benzene exposure. After urinary t,t-MA was extracted and enriched using solid-phase extraction, a MF-Ph1 SG80 ($150mm{\times}2.0mm$ I.D., 5 ${\mu}m$) column with a mobile phase of 10 mM $KH_2PO_4$ containing 0.1% $H_3PO_4$ was used for isocratic separation of t,t-MA with UV detection at 259 nm. The calibration curve was constructed in the range of 0.1-5.0 mg/L with good linearity ($r^2$=0.9992). The intra-day and inter-day precision (as RSD) were 0.9-8.5% and 3.1-4.5%, respectively. The average recovery ranged from 97.5% to 101.7%. The green sample preparation and separation with no organic solvents were successfully achieved. The validated method would be suitable for the routine biological monitoring of benzene exposure in the occupational settings.

• Journal of Pharmaceutical Investigation
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• v.39 no.1
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• pp.73-78
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• 2009

A simple LC-MS/MS method of rabeprazole in human plasma was developed and validated. Rabeprazole and Internal standard (I.S), omeprazole, were extracted from human plasma by liquid liquid extraction, chromatographic separation of rabaprazole in plasma was achieved at $45^{\circ}C$ with a Shiseido UG120 $C_{18}$ column and methanol-10 mM ammonium acetate buffer (pH 9.42 with ammonium water), as mobile phase. Rabeprazole produced a protonated precursor ion [$(M+H)^+$] at m/z 360.10 and corresponding product ion at m/z 242.21. Internal standard produced a protonated precursor ion [$(M+H)^+$] at 346.09 and corresponding product ion at m/z 198.09. This method showed linear response over the concentration range of $1{\sim}500\;ng/mL$ with correalation coefficient greater than 0.99. The lower limit of quantitation (LLOQ) using 0.2 mL plasma was 1 ng/mL, which was sensitive enough for pharmacokinetics studies. The method was specific and validated with a limit of quantitation of 1 ng/mL. The intra-day and inter-day precision and accuracy were acceptable for all samples including the LLOQ. The applicability of the method was demonstrated by analysis of plasma after administration of a single 10 mg dose to 36 healthy subject. From the plasma rabeprazole concentration versus time curves, the mean $AUC_t$ (The area under the plasma concentration-time curve from time 0 to 12 hr ) was $691.36{\pm}321.88\;ng{\cdot}hr/mL$, $C_{max}$ (maximum plasma drug concentration) of $353.21{\pm}131.52\;ng/mL$ reached $3.4{\pm}1.1\;hr$ after adiministration. The mean biological half-life of rabeprazole was $1.37{\pm}0.75\;hr$. Based on the results, this simple method could readily be used in pharmacokinetics studies.

• Journal of Korean Ophthalmic Optics Society
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• v.15 no.3
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• pp.227-234
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• 2010

Purpose: The cleaning effect of protein deposit and the change of contact lens parameters by ultrasonic cleaner for eye glasses on the soft contact lenses were investigated. Methods: Etafilcon A contact lenses contaminated with protein, was ultrasonicated by ultrasonic cleaner for eye glasses and for the control group, spoiled contact lenses were cleaned by multi-purpose solution. The remaining protein deposits on the contact lenses were determined after extraction and the changes of overall diameter, base curve, center thickness power, and water contents on contact lenses were measured and surfaces of contact lenses were observed by scanning electron microscope. Results: The cleaning efficacies of multi-purpose solution on protein deposited etafilcon A contact lenses were 6.08%, and 23.73~33.92% in the group of ultrasonic cleaner for eye glasses with multi-purpose solution and 0~12.99% in the group of ultrasonic clear for contact lens with multipurpose solution depending on the treatment time. The changes of parameters and surface on contact lenses by ultrasonication were not observed. Conclusions: Ultrasonic cleaner for eye glasses can be used to eliminate protein deposits for the diagnostic soft contact lens in the office since it was effective to eliminate protein deposits and not caused change of parameters on soft contact lenses.

• Proceedings of the Korea Inteligent Information System Society Conference
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• 2002.11a
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• pp.535-542
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• 2002

최근 IT 산업이 급성장하면서 화상 회의, 게임, 채팅 등에서의 아바타(avatar) 제어를 위한 자연스러운 인터페이스 기술이 요구되고 있다. 본 논문에서는 동적 윤곽선 모델(active contour models; snakes)을 이용하여 복잡한 배경이 있는 컬러 CCD 카메라 영상에서 얼굴과 눈, 입, 눈썹, 코 등의 얼굴 요소에 대해 윤곽선을 추출하거나 위치를 파악하는 방법을 제안한다. 일반적으로 스네이크 알고리즘은 잡음에 민감하고 초기 모델을 어떻게 설정하는가에 따라 추출 성능이 크게 좌우되기 때문에 주로 단순한 배경의 영상에서 정면 얼굴의 추출에 사용되어왔다 본 연구에서는 이러한 단점을 파악하기 위해, 먼저 YIQ 색상 모델의 I 성분을 이용한 색상 정보와 차 영상 정보를 사용하여 얼굴의 최소 포함 사각형(minimum enclosing rectangle; MER)을 찾고, 이 얼굴 영역 내에서 기하학적인 위치 정보와 에지 정보를 이용하여 눈, 입, 눈썹, 코의 MER을 설정한다. 그런 다음, 각 요소의 MER 내에서 1차 미분과 2차 미분에 근거한 내부 에너지와 에지에 기반한 영상 에너지를 이용한 스네이크 알고리즘을 적용한다. 이때, 에지 영상에서 얼굴 주변의 복잡한 잡음을 제거하기 위하여 색상 정보 영상과 차 영상에 각각 모폴로지(morphology)의 팽창(dilation) 연산을 적용하고 이들의 AND 결합 영상에 팽창 연산을 다시 적용한 이진 영상을 필터로 사용한다. 총 7명으로부터 양 눈이 보이는 정면 유사 방향의 영상을 20장씩 취득하여 총 140장에 대해 실험한 결과, MER의 오차율은 얼굴, 눈, 입에 대해 각각 6.2%, 11.2%, 9.4%로 나타났다. 또한, 스네이크의 초기 제어점을 얼굴은 44개, 눈은 16개, 입은 24개로 지정하여 MER추출에 성공한 영상에 대해 스네이크 알고리즘을 수행한 결과, 추출된 영역의 오차율은 각각 2.2%, 2.6%, 2.5%로 나타났다.해서 Template-based reasoning 예를 보인다 본 방법론은 검색노력을 줄이고, 검색에 있어 Feasibility와 Admissibility를 보장한다.매김할 수 있는 중요한 계기가 될 것이다.재무/비재무적 지표를 고려한 인공신경망기법의 예측적중률이 높은 것으로 나타났다. 즉, 로지스틱회귀 분석의 재무적 지표모형은 훈련, 시험용이 84.45%, 85.10%인 반면, 재무/비재무적 지표모형은 84.45%, 85.08%로서 거의 동일한 예측적중률을 가졌으나 인공신경망기법 분석에서는 재무적 지표모형이 92.23%, 85.10%인 반면, 재무/비재무적 지표모형에서는 91.12%, 88.06%로서 향상된 예측적중률을 나타내었다.ting LMS according to increasing the step-size parameter $\mu$ in the experimentally computed. learning curve. Also we find that convergence speed of proposed algorithm is increased by (B+1) time proportional to B which B is the number of recycled data buffer without complexity of computation. Adaptive transversal filter with proposed data recycling buffer algorithm could efficiently reject ISI of channel and increase speed of convergence in avoidance burden of computational complexity in reality when it was experimented having the same condition of

• Korean Journal of Environmental Agriculture
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• v.33 no.3
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• pp.205-212
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• 2014

BACKGROUND: This study focused on the contents of flavonoid compounds in vegetables. Generally vegetables have contributed to a healthy diet, arisen from contains a large amount of fiber and functional ingredients. And flavonoid compounds are one of major functional components in the vegetables. currently research of flavonoid contents does not enough, specially in the part of homegrown vegetable. METHODS AND RESULTS: Vegetable samples were purchased in domestic market. Sample extraction by methanol, distilled water, and formic acid based solvent. Also same solvent used for mobile phase in UPLC. Eleven types of flavonoid compounds were analyzed with same kind of external standard and one kind of internal standard (galangin) for quantification. Standard calibration curve presented linearity with the correlation coefficient $R^2$ > 0.98, analysed from 1 to 50 ppm concentration. The quantitative value and multivariate analysis results were derived from the Excel and SIMCA-P11. Overall, onion has largest amount(916.5 mg/100 g) of flavonoid and also other vegetables have has significant amount[Mugwort: 138.8, Galic stem:123.6 mg/100 g etc.] of flavonoid compounds. Edible portion of vegetables per share for simulating by SIMCA-P11, root vegetables has had difference with other vegetables according to distributions and amounts of flavonoid compounds. CONCLUSION: Optionally, the results from this experiment can use to select the material for flavonoid researches. And based on these results, if this experiment will be continuously complemented, and performed, could used in various fields.

• Analytical Science and Technology
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• v.24 no.3
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• pp.225-230
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• 2011

Anatoxin-a is a cyanobacterial neurotoxin with a high toxicity produced by Anabaena, Aphanizomenon and Oscillatoria. Water bloom, formed by Anabaena has been occurring frequently in Lake Yeongchun. It is need to develop a sensitive method for determination of anatoxin-a to control potential hazard in raw water resources. In this study, we developed a highly sensitive analytical method of anatoxin-a using solid phase extraction (SPE) and high performance liquid chromatography (HPLC) with fluorescence detection. Anatoxin-a was converted into a highly fluorescent derivative using 4-fuoro-7-nitro-2,1,3-benzoxadiazole (NBF-F). The method was evaluated in terms of linearity of calibration curve, recovery and repeatability, and the adequate values were obtained. The method detection limit was $0.034\;{\mu}g/g$ and $0.022\;{\mu}g/L$ for algal and water samples, respectively. The concentrations of anatoxin-a were measured in algal and water samples from Lake Andong, Yeongchun and Daechung and ranged from $0.135\;{\mu}g/g$ to $10.979\;{\mu}g/g$ in algal samples and not detected in water samples.

• Korean Journal of Veterinary Research
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• v.36 no.3
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• pp.541-550
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• 1996

Tetracycline antibiotics have been widely used not only therapeutics but feed additives. There are many methods for the isolation and determination of tetracycline antibiotics in animal muscle tissue. But those methods take much time and labor, so it is difficult to analyse many samples simultaneously. A rapid isolation method and liquid chromatographic determination of tetracycline antibiotics in animal muscle tissue (bovine, porcine, chicken) is presented. Blank control and tetracyclines fortified samples (0.5g) were blended with $C_{18}$ containing 0.05g each of oxalic acid and disodium ethylenediaminetetraacetate. After homogenize, homogenate was transferred to glass column made from 10ml glass syringe and compressed to 4~4.5ml volume. A column made from the $C_{18}$/meat matrix was washed with hexane (8ml) and dichloromethane (8ml, if needed), following which the tetracyclines were eluted,vith methanol or 0.01M methanolic oxalic acid (8ml). The eluates containing tetracyclines analytes were free from interfering compounds when analysed by HPLC with UV detection (photodiode array at 360nm). Standard curve for each tetracycline showed a linear response at the range of $0.05{\sim}1.0{\mu}g/ml$ and tetracycline antibiotics were eluted within 4ml of eluted volume. All tetracycline antibiotics except tetracycline were stable during the concentration process at $40^{\circ}C$ and time required for concentration was 3~4 hours. Fortified samples containing oxalic aicd and EDTA represented more good recoveries than those of not-contained sample. Recoveries were 91.8~110.1% (oxytetracycline; OTC), 57.7~79.5% (tetracycline; TC), 78.1~88.6% (chlortetracyclines; CTC) and 88.4~100.6% (doxycycline; DC) in pork tissue, 101.1~126.8% (OTC), 66.4~75.4% (TC), 79.2~88.1% (CTC) and 69.3~86.7% (DC) in beef tissue, and 90.8~95.6% (OTC), 66.2~84.4% (TC), 75.7~77.2% (CTC) and 55.6~80.7% (DC) in chicken muscle tissue. The detection limits validated in muscle tissue by this method were $0.05{\mu}g/g$ for OTC and TC, and $0.1{\mu}g/g$ for CTC and DC.

• Korean Journal of Food Science and Technology
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• v.31 no.3
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• pp.593-599
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• 1999

Substrate specificity of a flow-injection-analysis (FIA)-type biogenic amine sensor with enzyme reactor was determined. The enzyme reactor was prepared with a diamine oxidase immobilized on preactivated chitosan porous beads (Chitopearl) by intramolecular cross-linking via glutaraldehyde. The sensor showed a rapid response to putrescine and a quasi-linear calibration curve was obtained up to 15.0 mM. The optimal pH and temperature of the enzyme reactor system were 7.5 and $35^{\circ}C$. Interferences due to ATP-related compounds and trimethylamine, and the effects of NaCl and amino acids were measured. Inhibitory effects owing to these components could be mitigated by sample extraction with perchloric acid. Polyamines except putrescine were determined by a putrescine calibration range within 26.7%. This system was confirmed as rapid and convenient for biogenic amine determination.

• Korean Journal of Soil Science and Fertilizer
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• v.11 no.2
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• pp.75-80
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• 1979

Ammonium desorption from 16 soils treated with $(NH_4)_2HPO_4$ solution (2000 ppm $NH_4$) was investigated by seven extractions with 0.01M $CaCl_2$. 1. There were 2 to 4 steps alternately appeared with fast and slow mode. 2. Desorption equation, log y=b-ax where y is desorption amount, b a constant indicating adsorption maximum, a retention constant, and x extraction number, was held for each step. 3. Desorption rate (100${\times}$desorption / adsorption) was 65% for the average of 15 soils, maximum 87% in Gimcheon series, minimum 32% in Samgag series. Yongho series (a peat soil) showed 156% indicating the release of large quantity of indigenous soil ammonium. 4. Desorption rate was negatively correlated with initial adsorption and in this relation the tested soils were classified into 3 groups. 5. The cumulative desorption curve was approaching almost to maximum in all tested soils with seven extractions. The final retention amount, ranged from 25% of CEC (Gimhae series) to 502% (Samgag Series). 6. Amount and rate of desorption did not have any significant relation with Langmuir adsorption maxima of ammonium, CEC and contents of clay, available phosphorus and organic matter. 7. The above results may indicate that adsorption and desorption of ammonium is closely related with iron, aluminum silicate and adsorption and desorption characteristics of accompanied anions.