• Korean Journal of Veterinary Service
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• v.28 no.3
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• pp.203-213
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• 2005

Oxytetracycline, tetracycline, chlortetracycline and doxycycline in honey were separated by solid phase extraction (SPE) and determined with high performance liquid chromatography (HPLC) with UV/Visible detector. Analysis was carried out using following conditions: XTerra $C_8$ column $(3.9\times150mm\;i.d. 5{\mu}m)$, mobile phase composed of 0.01M oxalic acid : methanol : acetonitrile (820 : 80 : 100, v/v/v), isocratic pump at a flow rate of 0.9 ml/min. and $50{\mu}l$ of injection volume, UV/Visible detector with wavelength of 360nm. The calibration curves of four tetracyclines showed linearity $(\gamma^2>0.999)$ at concentration range of $100\~1,000 ng/ml$. The recoveries in fortified honey represented more than $70\%$ with low coefficient of variation $(<10\%)$ for concentration range of four tetracyclines. The detection limits for oxytetracycline, tetracycline, chlortetracycline and doxycycline were 13.8, 14.6, 26.2 and 24.9ng/g in acacia honey. respectively. We also monitored tetracyclines residue in domestic honey [n : 38, acacia (20), wild flower (18) ] and foreign honey [n=22, legally distributed (13), illegally distributed (9)] using modified Charm II screening and HPLC confirmation methods. Seven of the 60 samples $(11.7\%)$ were suspect positive using modified Charm II screening test. Chlortetracycline residue was found in one foreign honey (illegally distributed) tested at concentrations of 0.22 ppm. Conclusively, for more effective control of tetracyclines used in beekeeping should be further survey for residues in honey and also national guidelines (maximum residue limit : MRL) and methods should be obligatory.

• Archives of Pharmacal Research
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• v.9 no.4
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• pp.211-214
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• 1986

A simultaneous determination method of alkaline earth metals was attempted with the conventional high performance liquid chromatographic system. Four cations, namely, magnesium, calcium, strontium and barium ion, were injected directly as aqueous solution into an eluent containing copper chloride solution and and were successfully separated and determined on a separating column (Zipax SCX, 4.6 mm i.d. ${\times}25$ cm length, Du Pont, USA) by using a variable wavelength UV detector. The linear calibration curves were obtianed in the range from $1.0{\times}10^{-4}M$ to $5.0{\times}10^{-4}M$ and the correlation coefficient of the calibration curve for each metal of magnesium and calcium in tap water. Alkaline earth metals were determined with the conventional high performance liquid chromatographic system.

• The Korea Journal of Herbology
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• v.27 no.6
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• pp.43-48
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• 2012

Objectives : This study was investigated to determine the contents of pesticide residues and sulfur dioxide residues in commercial herbal medicines in Korea. Methods : Chromatographic test was performed on 100 samples consisted with 10 kinds of medicinal plants including improted and domestic products. To establish 19 pesticide residues (DDE, DDD, DDT, Dieldrin, Methoxychlor, BHC isomers, Aldrin, Endosulfan isomers, Endrin, Captan, Procymidone, Chlorpyrifos and Imidacloprid) in commercial herbal medicines, chromatographic equipments were used with the gas chromatography-mass detector and gas chromatography-electron capture detector for qualitative analysis. The imidacloprid analysis was performed by high performance liquid chromatograpgy-ultraviolet detector at 270 nm UV wavelength. The contents of sulfur dioxides were analyzed by modified Monnier-Williams method. All methods were based on notification procedure of Korea Food & Drug Administration (KFDA). Results : The residual pesticides were not founded in improted and domestic samples. Among 100 samples, the residues of sulfur dioxide in 73 samples were not detected and 25 samples showed contents in the range of 0~21.90 mg/kg. The excess samples of MRLs were 2 samples (30 mg/kg to medicinal herbs), Asiasari Radix et Rhizoma (Imported product) and the average amount of sulfur dioxide in 2 unsuitable samples were 14.83 mg/kg. These samples were found to transgress KFDA regulatory guidance of residual sulfur dioxide. Conclusion : These results are able to use as basic data to improve the reliability and value of commercial medicinal herbs.

• Journal of the Korean Chemical Society
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• v.33 no.1
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• pp.46-54
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• 1989

The extraction method and quantitative analysis for the fat-soluble vitamins present in food stuffs and vitamin products have been investigated. The simultaneous separation and analysis of the vitamins by reverse phase high performance liquid chromatographic method was conducted using an isocratic elution with methanol : water (95 : 5) eluent on a Novapak $C_{18}$ column. The detection of vitamins was achieved by a variable wavelength UV detector. To improve the detection sensitivity detection wavelengths were set at the highest absorption bands such as 330, 265, 285, and 290nm for the respective vitamins. The analysis for the fat-soluble vitamins was finished within 40 minutes. Alkaline hydrolysis and enzymatic hydrolysis were investigated for the sample preparation; and liquid-liquid extraction and liquid-solid extraction were attempted for the extraction of vitamins. Both hydrolysis methods were turned out to be appropriate for the analysis for vitamins A, D, and E, while for the analysis of vitamin K the enzymatic hydrolysis method demonstrated better results. Diethyl ether, pentane, and n-hexane were found to give higher recovery for the liquid-liquid extraction and silica cartridge for the liquid-solid extraction.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.7
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• pp.486-493
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• 2003

Schottky type A $l_{0.33}$G $a_{0.67}$N ultraviolet photodetectors were fabricated on the MOCVD grown AlGaN/ $n^{＋}$-GaN and AlGaN/AlGaN interlayer/ $n^{＋}$-GaN structures. The grown layers have the carrier concentrations of -$10^{18}$, and the mobilities were 236 and 269 $\textrm{cm}^2$/V.s, respectively. After mesa etching by ICP etching system, the Si3N4 layer was deposited for passivation between the contacts and Ti/AL/Ni/Au and Pt were deposited for ohmic and Schottky contact, respectively. The fabricated Pt/A $l_{0.33}$G $a_{0.67}$N Schottky diode revealed a leakage current of 1 nA for samples with interlayer and 0.1$\mu\textrm{A}$ for samples without interlayer at a reverse bias of -5 V. In optical measurement, the Pt/A $l_{0.33}$G $a_{0.67}$N diode with interlayer showed a cut-off wavelength of 300 nm, a prominent responsivity of 0.15 A/W at 280 nm and a UV-visible extinction ratio of 1.5x$10^4./TEX>.

• Biomolecules & Therapeutics
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• v.16 no.2
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• pp.168-172
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• 2008

The present study is to determine of sensitive nicorandil analysis method using HPLC and measure the pharmacokinetics parameters (bioavailability, $C_{max}$, $T_{max}$, Ke, $T_{1/2}$) of nicorandil (5 mg, Tab; Choongwae Pharma Corporation). Plasma (500 ul) was mixed with furosemide (internal standard, 500 ug/ml). Detection wavelength was 256 nm. The mixture of 0.01 M ammonium acetate and acetonitrile 80:20 (v/v) was used mobile phase. The HPLC separation was accomplished on ODC reverse HPLC column. The nicorandil was analyzed by a HPLC system, which consists of CAPCELL PAK C18 column (5 ${\mu}$m, 4.6 × 150 mm) and a chromatography data analysis S/W, using a isocratic mobile phase (mixture of 0.01 M ammonium acetate and acetonitrile 80:20 ) at 1.0 ml/min. Its sensitivity, selectivity, accuracy and precision must be adequate for the bioavailabilty study of nicorandil, and the linearity ($r^2$ ≥ 0.9994) of nicorandil was also proved in the range of 0.05 ug/ml . 3 ug/ml. The pharmacokinetic parameters of nicorandil (5 mg) tablets were measured as the follow. AUC: 0.19 ug/ml·hr, $C_{max}$: 0.14 ug/ml, $t_{max}$: 0.58 hr, Ke: 0.11 hr., $t_{1/2\beta}$: 6.76 hrs. This method is simple and sensitive HPLC method using UV detector for determination of nicorandil in human plasma.

• Analytical Science and Technology
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• v.32 no.6
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• pp.217-224
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• 2019

In this study, to evaluate the effectiveness and safety of oral therapy using Gastrodiae Rhizoma, a new HPLC-PDA analysis method was developed for the simultaneous quantitation of the three major components: (1) gastrodin, (2) gastrodigenin, and (3) p-hydroxybenzaldehyde, in steam processed and unprocessed tubers of Gastrodia elata Blume. The clear separation of the three components was achieved on a C18 column (250 × 4.6 mm, 5 ㎛) by gradient elution using water (including 0.1 % formic acid) and acetonitrile as the mobile phase. The flow rate was 1.0 mL/min, and the UV detector wavelength was set at 270 nm. The results demonstrate satisfactory linearity, recovery, precision, accuracy, stability, and robustness. The established HPLC-PDA method was applied to quantify three major compounds in 59 samples of G. elata Blume tubers. Finally, the steam processed and unprocessed tubers of G. elata Blume were successfully distinguished by pattern recognition analysis.

• 정보저장시스템학회:학술대회논문집
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• 2005.10a
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• pp.154-159
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• 2005

The next generation of optical storage systems requires higher numerical aperture (NA) objective lenses and shorter wavelength laser in order to improve the unit areal density. A blu-ray technology satisfies a miniaturization and a high capacity which are the requirements of the portable device. In this paper, we analyze the optical performance of hybrid micro lens and do active alignment. The hybrid micro lens is manufactured by using a wafer based fabrication technology. Optical components of hybrid micro lens are evaluated. The measurement of the optical power, the spot size and the wavefront error awe performed to evaluate the hybrid micro lens with NA 0.85. Using the measured data, we estimate if the performance of hybrid micro lens corresponds to the designed performance. After the performance of hybrid micro lens is evaluated, the integrated optical pickup and the hybrid micro lens are assembled by active alignment using UV curing and the optical performance of SFFOP is satisfied with BD specifications.

• Bulletin of the Korean Chemical Society
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• v.25 no.3
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• pp.357-360
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• 2004

We developed in the present study molecular imprinted polymers (MIPs), using single templates (pentoxifylline, caffeine and theophylline) and mixed-templates (pentoxifylline-caffeine, pentoxifylline-theophylline and caffeine-theophylline). The MIPs were prepared with methacrylic acid (MAA) as the monomer, ethylene glycol dimetharylate (EGDMA) as the crosslinker and 2,2'-azobis(isobutyronitrile) (AIBN) as the initiator. The obtained polymer particles (particle size after grinding was about 25-35 ${\mu}$m) were packed into a HPLC column (3.9 mm i.d. ${\times}$ 150 mm). The selectivity and chromatographic characteristics of the MIPs were studied using acetonitrile as the mobile phase at a flow rate of 0.8 mL/min. UV detector wavelength was set at 270 nm. Different single template MIPs showed different molecular recognitions to the templates and the structurally analogues, according to the rigidity and steric hindrance of the compounds. Recognition was improved on the mixed-template MIPs as a result of the cooperation or sum effect of the templates, whereas on the pentoxifylline-theophylline imprinted polymer, the highest selectivity and affinity were obtained. Separations of the test compounds on different polymers were also investigated.

• Preventive Nutrition and Food Science
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• v.7 no.1
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• pp.1-4
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• 2002

Eleven flavonoids, including rutin, naringin, hesperidin, neohesperidin, quercetin, naringenin, kaempferol, hesperetin, nobiletin, 3,5,6,7,8,3',4'-methoxylated flavone and tangeretin in the peel of late maturing citrus fruit species of Mucott (smith tangerine), Singamha (C. natsudidai), Sambogam (C. sulcata), Hongpalsak (C. hassaku), Seminol (Dancy tangerine) and Jawdung (C. aurantium) harvested during from August to December were analyzed with HPLC. The mobile phase consisted of water and acetonitrile with 0.5% acetic acid. Wavelength in UV detector was determined at 254 nm. Naringin and neohesperidin content in the peel of Jawdung harvested at the early stage of maturation were 34.02 mg/g and 13.68 mg/g, respectively, and it was highest among the tested citrus fruits. Hesperidin content in the peel of Mucott harvested at the earthy stage of maturation was 12.48 mg/g. Rutin content of Sambogam harvested at the early stage of maturation was 5.13 mg/g. Quercetin, naringein, kaempferol, nobiletin, 3,5,6,7,8,3',4'-methoxylated flavone flavonoids were in trace. Flavonoid contents of Singamha, Sambogam and Jawdung were high in the peel of fruits at the early stage of maturation, after which time they decreased rapidly.