• The Bulletin of The Korean Astronomical Society
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• v.35 no.2
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• pp.63.1-63.1
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• 2010

CQUEAN (Camera for QUasars in EArly uNiverse) is a newly developed camera system by CEOU optimized at 0.8 - $1.1{\mu}m$ wavelength region. From Aug. 10 to Aug. 17, 2010, the camera was installed at 2.1m Otto Struve telescope at McDonald Observatory, USA, and engineering test observation was performed. We obtained the data for the characteristics of camera and scientific purpose using 7 filters (g, r, i, z, Is, Iz, Y). For the purpose of discovery of z - 5~6 quasar, we specially used new filters (Is,Iz). During the test observation, we obtained the data of Gamma-Ray Burst, high redshift quasars, high redshift quasar candidates and other calibration data. We present general characteristics of the reduced data taken with CQUEAN and show the performance of the camera.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.398-403
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• 2000

Experimental study on the porous ceramic burner for oil burning has been performed. Temperature profile of the combustor and CO and NOx emission have been obtained for with and without porous ceramic plate. It is found that very uniform and high temperature region with porous ceramic plate can be realized due to high radiation emission from the plate and also obtained lower CO and soot particulate emission, when compared to the conventional burner. When this burning method is applied to conventional boiler of small heating capacity, it is found that near 6 and 7 percent increase in thermal efficiency could be obtained without a proper calibration for optimization.

• Korean Journal of Plant Resources
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• v.30 no.6
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• pp.693-698
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• 2017

The quality control of natural products is principal key to guarantee the Good Manufacturing Practices (GMP) and Good Clinical Practices (GCP) for the functional food, pharmaceuticals and cosmeceuticals in the industry. In this study, we examined the quantitative analysis of berberine as marker substance of Coptidis Rhizoma by high performance liquid chromatography-photodiode array detector (HPLC-DAD). The HPLC method was validated and met all the requirements for the quality control analysis recommended by FDA and ICH. The berberine was separated on a Xterra $C_{18}$ column ($5{\mu}m$, $4.6{\times}250mm$) using mobile phase consisting of distilled water and acetonitrile with $KH_2PO_4$ (3.4 g) and $Na_2SO_4$ (1.7 g). Calibration curve of berberine has been estimated (y = 42293.47x-41589 with the correlation coefficient 0.9999). The amount of berberine was calculated as 4.25%. And berberastine, palmatine, columbamine, jatrorrhizine, epiberberine, berberine and coptisine in the Coptidis Rhizoma were identified by high performance liquid chromatography - electrospray ionization-mass spectrometer (HPLC-ESI-MS) method.

• YAKHAK HOEJI
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• v.58 no.3
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• pp.158-164
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• 2014

Dangguisu-san is a well-known traditional Korean herbal medicine prescription and has been widely used to treat ecchymosis, blood stagnation, and pain resulting from physical shock in Korea. In this study, an ultra-performance liquid chromatography-electrospray ionization-mass spectrometer method was established for the simultaneous determination of the 17 biomarker components in Dangguisu-san. All analytes were separated on an UPLC BEH $C_{18}$ ($100{\times}2.1$ mm, $1.7{\mu}m$) column and maintained at $45^{\circ}C$. The mobile phase consisted of two solvent systems, 0.1% (v/v) formic acid in water (A) and acetonitrile (B) by gradient flow. The injection volume was $2.0{\mu}l$ and the flow rate was 0.3 ml/min with detection at mass spectrometer. Calibration curves of the 17 biomarker components were acquired with $r^2$ values ${\geq}0.9951$. The values of limit of detection and quantification of all analytes were 0.02~6.32 ng/ml and 0.05~18.95 ng/ml, respectively. The amounts of the 17 components in Dangguisu-san sample were $3.17{\sim}13,224.50{\mu}g/g$.

• Herbal Formula Science
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• v.21 no.1
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• pp.177-185
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• 2013

Objectives : Leejung-tang (Lizhong-tang) has been used for treatment of gastrointestinal disorders in Korea. In this study, we performed quantification analysis of five marker components, liquiritin, ginsenoside Rb1, ginsenoside Rg1, glycyrrhizin, and 6-gingerol in Leejung-tang using a ultra performance liquid chromatography- electrospray ionization-mass spectrometer (UPLC-ESI-MS). In addition, we evaluated antioxidant activity of Leejung- tang. Methods : The column for separation of five constituents used a UPLC BEH C18 ($100{\times}2.1mm$, $1.7{\mu}m$) maintained at $45^{\circ}C$. The mobile phase consisted of two solvent systems, 0.1% (v/v) formic acid in H2O (A) and CH3CN (B) by gradient flow. The flow rate was 0.3 mL/min with detection at mass spectrometer. The antioxidative activities conduct an experiment on 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 2,2-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activities of Leejung-tang. Results : Calibration curves of five marker compounds were acquired with r2 values > 0.99. The amount of the five compounds in Leejung-tang were 0.07 - 0.84 mg/g. The concentration required for 50% reduction (RC50) against ABTS radical was 119.02 ug/mL. In addition, the scavenging against DPPH radical of Leejung-tang was 11.4%, 14.5%, 19.8%, 29.6%, and 49.2% at 25 ug/mL, $50{\mu}g/mL$, $100{\mu}g/mL$, $200{\mu}g/mL$, and $400{\mu}g/mL$, respectively. Conclusions : The established LC-MS/MS method will be helpful to improve quality control of Leejung-tang. In addition, Leejung-tang is a potential antioxidant therapeutic agent.

• Journal of Food Hygiene and Safety
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• v.36 no.1
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• pp.24-33
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• 2021

For this study, we surveyed concentrations of 8 mycotoxins (aflatoxin B1, B2, G1, G2, ochratoxin A, fumonisin B1, B2 and zearalenone) in agricultural products used for food and medicine by liquid chromatography-tandem mass spectrometry and conducted a risk assessment. Samples were collected at the Yangnyeong Market in Seoul, Korea, between January and November 2019. Mycotoxins were extracted from these samples by adding 0.1% formic acid in 50% acetonitrile and cleaned up by using an ISOLUTE Myco cartridge. The method was validated by assessing its matrix effects, linearity, limit of detection (LOD), limit of quantification (LOQ), recovery and precision using four representative matrices. Matrix-matched standard calibration was used for quantification and the calibration curves of all analytes showed good linearity (r2>0.9999). LODs and LOQs were in the range of 0.02-0.11 ㎍/kg and 0.06-0.26 ㎍/kg, respectively. Sample recoveries were from 81.2 to 118.7% and relative standard deviations lower than 8.90%. The method developed in this study was applied to analyze a total of 187 samples, and aflatoxin B1 was detected at the range of 1.18-7.29 ㎍/kg (below the maximum allowable limit set by the Ministry of Food and Drug Safety, MFDS), whereas aflatoxin B2, G1 and G2 were not detected. Mycotoxins that are not regulated presently in Korea were also detected: fumonisin (0.84-14.25 ㎍/kg), ochratoxin A (0.76-17.42 ㎍/kg), and zearalenone (1.73-15.96 ㎍/kg). Risk assessment was evaluated by using estimated daily intake (EDI) and specific guideline values. These results indicate that the overall exposure level of Koreans to mycotoxins due to the intake of agricultural products used for food and medicine is unlikely to be a major risk factor for their health.

• Analytical Science and Technology
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• v.28 no.6
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• pp.417-424
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• 2015

In this study, the relationship between selenoprotein concentrations in blood and stomach cancer have been searched for Korean. The concentration of each selenoprotein in blood serum was analyzed and the correlation between the concentration and stomach cancer was studied to find a potential for using Selenium as a biomarker. In concentration determination, a simple calibration curve method was used with the monitoring of m/z 78 without the use of solid phase extraction. This is a lot more simple than the method using SPE with post column isotope dilution. The result obtained from the analysis of CRM BCR-637, 72.20±3.35 ng·g⁻¹, showed similar value of reference value (81±7 ng·g⁻¹). The total concentration of Se for the controlled group, cardiovascular patients group, was 105.70±21.20 ng·g⁻¹. This value was the same as normal healthy person reported earlier. Each selenoprotein concentration of GPx, SelP and SeAlb was 26.12±7.84, 65.15±14.50, 14.43±6.99 ng·g⁻¹, respectively. The distribution of each selenoprotein was 24.7%, 61.6%, and 13.7%, which was similar to the normal person. The result of stomach cancer patients, the total concentration of Se was 76.11±28.12 ng·g⁻¹ and each concentration of GPx, SelP and SeAlb was 15.41±9.01, 50.83±17.91, and 9.87±5.21 ng·g⁻¹, respectively. The total and each selenoprotein concentration level showed significant decrease for the stomach cancer patients. The level of decrease was 41.0% for GPx, 22.0% for SelP, and 31.6% for SeAlb. However, the distribution of each selenoprotein was not much different. Either total Selenium or each selenoprotein could be used as a possible index for the diagnosis of cancer. However, in age group study, it is shown that young age group (30's-40's) did not show much difference.

• Journal of Food Hygiene and Safety
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• v.32 no.3
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• pp.193-198
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• 2017

Scutellaria baicalensis, Eleutherococcus senticosus, and Angelica sinensis have been used as raw materials for health functional foods. This study was conducted to develop a novel method to analyze levels of baicalin (Scutellaria baicalensis), eleutheroside E (Eleutherococcus senticosus), and ligustilide (Angelica sinensis) simultaneously in health functional foods. The methanol extracted samples were analyzed and quantified via liquid chromatography-tandem mass spectrometry (LC-MS/MS) in the positive ion mode and the negative ion mode using multiple reaction monitoring. Standard calibration curves confirmed linearity with the correlation coefficient ($r^2$) of > 0.99 at $100-2000{\mu}g/mL$ concentration range. The limits of detection (LODs) and limits of quantitation (LOQs) were in the range of $13.0{\sim}35.2{\mu}g/L$ and $39.3{\sim}106.7{\mu}g/L$, respectively. The recovery results ranged between 91.4~109.9% at 3 different concentration levels with relative standard deviations (RSDs) less than 5%. The proposed analytical method was characterized with high accuracy and acceptable precision. The new method would be an effective tool to analyze baicalin, eleutheroside E, and ligustilide simultaneously in raw materials of health functional foods.

• Journal of the Korean Chemical Society
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• v.56 no.5
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• pp.583-590
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• 2012

The HF (Hollow fiber) extraction method was optimized to analysis seven species of pesticides in aqueous sample and analyzing samples by GC/MS. Hollow fiber extraction showed good efficiency when it was conducted under these conditions: organic solvent was toluene and agitation speed was 1200 rpm. The 15% concentration of NaCl was optimized when it was experimented between 5% and 25%. The equilibrium time was determined at 15 minutes. The pH 5 showed the best effect on the extraction efficiency. The linearities of calibration curves of seven species were good with correlation of regression ($r^2$) over 0.995 when they were experimented over a concentration range of $5{\mu}g/L$ to $50{\mu}g/L$. The analytical data exhibited the detection of limits (LODs) range of $0.37{\mu}g/L$ to $1.23{\mu}g/L$ and the limit of quantification (LOQs) range of $1.19{\mu}g/L$ to $3.91{\mu}g/L$. The optimized HF-LPME extraction method provides a simple and effective preparation and requires small amount of organic solvents and samples compared to conventional pre-treatment methods.

• Preventive Nutrition and Food Science
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• v.19 no.4
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• pp.321-326
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• 2014

In this study, we developed a method to quantify esculetin (6,7-dihydroxycoumarin) in plasma and tissues using HPLC coupled with ultraviolet detection and measured the level of esculetin in rat plasma after oral administration. The calibration curve for esculetin was linear in the range of 4.8 ng/mL to 476.2 ng/mL, with a correlation coefficient ($r^2$) of 0.996, a limit of detection value of 33.2 ng/mL, and a limit of quantification value of 100.6 ng/mL. Recovery rates for the 95.2 ng/mL and 190.5 ng/mL samples were 95.2% and 100.3%, within-runs and 104.8% and 101.0% between-runs, respectively. The relative standard deviation was less than 7% for both runs. In the pharmacokinetic analysis, the peak plasma esculetin level was reached 5 min after administration ($C_{max}=173.3ng/mL$; $T_{1/2}=45min$; $AUC_{0{\sim}180min}=5,167.5ng{\cdot}min/mL$). At 180 min post-administration (i.e., after euthanasia), esculetin was only detectable in the liver ($30.87{\pm}11.33ng/g$) and the kidney ($20.29{\pm}7.02ng/g$).