• Applied Biological Chemistry
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• v.31 no.1
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• pp.106-113
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• 1988

The rice lamina inclination test indicated the presence of brassinosteroid-like active substances in immature Vicia faba seeds. Two of these were identified as castasterone and brassinolide by GC/MS and GC/SIM, respectively. Another active principle was identified as methyl 4-chloroindole-3-acetate by GC/MS and HPLC.

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.402.1-402.1
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• 2002

The LC/MS/MS method for the simultaneous determination of sildenafil and its active metabolite N-demethylsildenafil in human plama was developed. Sildenafil. its active metabolite and the internal standard. DA-8159 were extracted form human plasma by liquid-liquid partitioning. A reverse-phase HPLC separation was performed on Luna phenylhexyl column with the mixture of acetonitrile-5 mM ammonium formate (55:45. v/v) as mobile phase. (omitted)

• Analytical Science and Technology
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• v.20 no.2
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• pp.115-123
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• 2007

The heterocyclic amines (HAs) are a family of mutagenic/carcinogenic chemicals formed from the cooking of muscle meats such as beef, meat, fowl, and fish. A major draw back in the analysis of HAs from foods is their very low level of concentration (ng/g) and a number of matrix interferences in samples. Solid-phase extraction (SPE) is one of the procedures widely used for the extraction and purification of HAs in food samples. In this study, several SPE procedures of HAs determination were performed. Recoveries of the HAs were obtained from comparing a matrix such as a standard methanolic solution and pre-cooked meat extracts. Recovery values were ranging between 25.3 and 93.0 % at a concentration of 25.0 ng/g. HAs were determined with high sensitivity by micro-HPLC (${\mu}$-HPLC) analysis with electrospray ionization mass spectrometry (ESI-MS). Another developed method, which is freezing filtration method, shows better extraction recoveries and good precisions. The established method will be applicable to monitoring of heterocyclic amines from the cooked meat.

• Analytical Science and Technology
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• v.7 no.1
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• pp.41-52
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• 1994

The importance of separation comes from demands on study for exact effect of synthetic drugs and the reactivity of enantiomer in biological system. Racemization rate was measured under the influence of heat, acid, UV-light, enzyme(trypsin) and 6N-HCl at $105^{\circ}C$ on alanine, threonine, isoleucine, lecuine, aspartic acid, methionine, glutamic acid, tyrosine. The method for the identification of overlapped amino acids with GC was developed from the close study of fragmentation pattern with mass spectrometry. With cyclodextrin bonded phase by HPLC, the separation of dansyl amino acid was tested for compartison.

• Korean Journal of Food Science and Technology
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• v.39 no.4
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• pp.372-379
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• 2007

A high-performance liquid chromatography-electrospray ionization (HPLC-ESI) tandem MS was developed for the rapid and simultaneous determination of forbidden medicines in dietary supplements. Thirteen medicinal components such as PDE-5 inhibitors and their analogues, and the newly identified dimethylsildenafil and xanthoanthrafil, were included in this study. After tentative standardization of molecular ions in both polarities using thirteen references on the mass spectrometer, with ESI-continuous infusion via the syringe pump method, the relative intensity of the ions present in the resulting spectra was quantitatively compared. From the results, the ion mode was selected depending on each reference's characteristics. A HPLC method coupled with the ESI mode was developed considering the matrix effect and interference depending on the type of sample. The validation test of the developed method was followed by carrying out precision, accuracy, recovery, sensitivity and linearity, etc. The method showed sufficiently high sensitivity, reproducibility, and specificity, and produced 4 times faster results when compared with the existing HPLC/UV method for the determination of forbidden compounds in dietary supplements.

• Analytical Science and Technology
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• v.20 no.2
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• pp.138-146
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• 2007

A simple and sensitive method for the determination of paroxetine in canine plasma was developed and validated by liquid-liquid extraction and liquid chromatography-tandem mass spectrometry (LC-/MS/MS). Fluoxetine was used as an internal standard. Paroxetine and internal standard in plasma samples were extracted using TBME (tert-butyl methyl ether). A centrifuged upper layer was then evaporated and reconstituted with mobile phase of 50% acetonitrile adjusted to pH 3 by formic acid. The reconstituted samples were injected into a Capcell Pak UG120 ($2.0{\times}150mm$, $5{\mu}m$) column. Using MS/MS with SRM (selective reaction monitoring) mode, the transitions (precursor to product) monitored were m/z $330{\rightarrow}192$ for paroxetine, and m/z $310{\rightarrow}148$ for internal standard. Linear detection responses were obtained for paroxetine concentration range of 0.02~5 ng/mL. A correlation coefficient of linear regression ($R^2$) was 0.9993. Detection of paroxetine in canine plasma was accurate and precise, with limit of quantification at 0.02 ng/mL. The method has been successfully applied to pharmacokinetic study of paroxetine in healthy beagle dogs.

• Journal of the Korean Chemical Society
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• v.63 no.6
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• pp.420-426
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• 2019

Selenoproteins,in Korean blood serum, GPx, SelP, and SeAlb were separated and determined with the use of HPLC-ICP/MS. Deuterium was used as a collision gas and affinity column with ammonium formate was used as an eluting solvent for the accurate quantitation of selenoproteins in human blood serum. Certified reference material BCR 639 (133±12 ng g^-1) was tested for the accuracy and the result was satisfactory 130±6 ng g^-1. Blood serum for the rectal cancer and controlled groups were collected and analyzed to give 84±27 ng g^-1, and 119±28 ng g^-1, respectively. The difference was statistically obvious when t-test was performed (t_cal 4.93 > t_95% 2.04). The decrease for cancer group was more obvious for female and aged group. The distributions of three selenoproteins were similar with each other, which means rectal cancer group did not show any specificity for any selenoproteins. As cancer developed, GPx showed a slight decrease but not obvious while the total concentration was increasing particularly at the second stage of cancer.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.33 no.2
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• pp.153-157
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• 2000

Hydrolysate which inhibit the Angiotensin I-converting enzyme (ACE) was prepared from mackerel muscle by pretense. The ACE inhibitory activity of mackerel muscle hvdrolysate (MMH) was $967 {\mu}g of IC_(50)$. ACE inhibitory peptides were isolated by ultrafiltration, gel permeation column chromatography (GPC), reversed phase column chromatography(RPC), reversed phasehigh performance liquid chromatography (RP-HPLC), and gel permeation high performance liquid chromatography (GP-HPLC) from the MMH. The amino acid sequence of the ACE inhibitory peptides was Tyr-Val-Ala. The $IC_(50)$ of this peptide for ACE from rabbit lung was $1.4 {\mu}M$.

• The Korean Journal of Pesticide Science
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• v.15 no.3
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• pp.238-245
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• 2011

This study was carried out to examine residual pesticides in dried agricultural products collected from Gyeonggi province in 2010. A total of 102 samples was collected and analyzed for 206 pesticides by multiresidue method using GC-${\mu}ECD$, GC-NPD, GC/TOF/MSD, HPLC-UVD, HPLC-FLD and HPLC/MS/MS. The detection rate of residual pesticides was 23.5% (24 of 102 samples) and the agricultural products exceeding their MRLs (Maximum Residue Limits) were 1 sample of pepper leaves. Additionally, the frequently detected pesticide were chlorothalonil, fenvalerate, chlorpyrifos, endosulfan, bifenthrin, cypermethrin, hexaconazole and iprodione. The pesticide types detected in the dried agricultural products showed in the descending order of organophosphorus (22%), pyrethroid (22%), organochloride (17%), dicarboxymide (11%), carboxymide (6%), carbamate (6%), triazole (5%) and the others (11%).

• Korean Journal of Food Science and Technology
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• v.33 no.3
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• pp.282-287
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• 2001

This study was carried out to investigate the difference of ginsenoside compositions in crude ginseng saponins prepared by five different methods including three new methods. Two known methods are hot methanol(MeOH) extraction/n-butanol(n-BuOH) fractionation and hot MeOH extraction/Diaion HP-20 adsorption/MeOH elution. Three new methods are hot MeOH extraction/cation AG 50W $absorption/H_2O$ elution/n-BuOH extraction, cool MeOH extraction/Diaion HP-20 adsorption/MeOH elution and direct extraction with ethyl acetate(EtOAc)/n-BuOH. Analysis of ginsenoside composition in the crude saponins by conventional HPLC/RI(Refractive Index) did not show great difference between methods except EtOAc/n-BuOH method. However, HPLC/ELSD (evaporative light scattering detector) employing gradient mobile phase afforded fine resolution of ginsenoside Rf, $Rg_1$ and $Rh_1$, and great difference of ginsenoside compositions between methods. LC/MS revealed that large amount of prosapogenins were produced during the pass through the cation exchange (AG 50W) column being strongly acidic. Six major ginsenosides such as $Rb_1,w;Rb_2,$ Rc, Rd, Re and $Rg_1$, 5 prosapogenins and one chikusetsusaponin were identified by LC/MS. A newly established HPLC method employing ODS column and gradient mobile phase of $KH_2PO_4/CH_3CN$ revealed that malonyl ginsenosides were detected only in the crude saponin obtained from cool MeOH extraction.