• Proceedings of the PSK Conference
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• 2002.10a
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• pp.401.3-402
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• 2002

Enalapril (ENP) maleate is effective drug for the treatment of renivascular hypertension and heart failure. ENP acts as inhibitor of the enzyme angiotensin-convertase (ACE-inhibitor) and metabolized to enalaprilat (ENPT), which is the active metabolite that is really responsible for the therapeutic action. In the present study, a sensitive and rapid liquid chromatography/ electrospray ion trap tandem mass spectrometry (LC/MS/MS) method combined with high-throughput solid phase extraction (SPE) has been developed and validated for the simultaneous quantitative determination of ENP and ENPT in human plasma. (omitted)

• BMB Reports
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• v.43 no.7
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• pp.506-511
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• 2010

The levels of salivary cortisol and cortisone in Korean adults were measured for the first time using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The salivary cortisol and cortisone were separated within 10 min. The regression coefficients (r) of the calibration curves were greater than 0.999 for the two steroids. The limits of quantitation (LOQ) were 0.2 ng/ml for cortisol and 1 ng/ml for cortisone. The intra-day precisions of the assay were <3.9% and 8.6% for cortisol and cortisone respectively, and the inter-day precisions were <1.9% and 4.3% for cortisol and cortisone, respectively. The salivary cortisone concentrations were approximately 4-9 times higher than those of salivary cortisol during the daytime. Diurnal rhythms, during which the cortisol and cortisone concentrations were higher in the morning than in the afternoon, were also observed. The present assay may be useful for the diagnosis of several adrenal dysfunctions in clinical biochemistry.

• Analytical Science and Technology
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• v.23 no.4
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• pp.405-413
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• 2010

A new method for the simultaneous determination of six glucocorticoids (betamethasone, dexamethasone, prednisone, prednisolone, methylprednisolone, and flumethasone) in meats (bovine muscle, bovine liver) were established. Samples were effectively extracted using C18 cartridge with ethylacetate. Chromatographic separation was achieved using C18 column and negative electrospray ionization mass spectrometry was performed in the Multiple Reaction Monitoring mode for the effective quantitation and qualification of glucocorticoids. Acetonitrile and water (0.1% formic acid) were used as mobile phase and additive for effective electrospray ionization, and gave good chromatographic separation and mass spectrometric sensitivity. The limit of detection (LODs) and the limit of quantitation (LOQs) in spiked blank samples depending on types of matrix and pharmaceuticals were ranged from 0.2 to $1.0\;{\mu}g$/kg and 0.8 to $3.4\;{\mu}g$/kg, respectively. And the recoveries were between 89.5 to 119.6%. The established method showed good recoveries, accuracies, precisions and fast sample preparation and it will be applied to assay of glucocorticoids residues in meat.

• Analytical Science and Technology
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• v.16 no.1
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• pp.59-69
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• 2003

Benzophenone (BZP) and 4-nitrotoluene (4-NT) listed as endocrine disrupting chemicals are suspected to contaminate ground water sites and soil. Analytical method for simultaneous determination of the two chemicals in soil and ground water was developed by gas chromatography-mass spectrometry. Water (100 ml) was extracted with hexane, and soil (10 g) was extracted with methanol and hexane. Recovery in water was >72% for BZP and 90-118% for 4-NT. Recovery for 4-NT and BZP in soil was 51-59% with coefficient variation of less than 19.5%. Calibration curves showed a good linearity with $r^2=0.997$. In water and soil collected at nation-wide sites, BZP was found at 5 sites among 43 water sites at the concentration of $14.87{\pm}3.83ng/100 ml$. No 4-NT was found. It is suggested that this method is appropriate to the simultaneous quantitation of 4-NT and BZP in ground water and soil samples.

• Natural Product Sciences
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• v.19 no.3
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• pp.236-241
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• 2013

A high-performance liquid chromatography-diode array detector (HPLC-DAD) method was established for quantitative evaluation of nine constituents of Fraxinus rhynchophylla such as four coumarins, esculin (1), fraxin (2), esculetin (3), fraxetin (4), three lignans, syringaresinol 4,4'-O-${\beta}$-diglucoside (5), pinoresinol 4-O-${\beta}$-glucoside (6), pinoresinol (9), one secoiridoid, oleuropein (7), and one coumarinolignan, cleomiscosin C (8). The preferred chromatographic condition was obtained on Phenomenex Gemini-NX (3 ${\mu}m$, C18 110A, $150{\times}4.60$ mm) and the mobile phase was composed of water and acetonitrile using a gradient elution. The wavelength was set at 220 nm. Extraction condition of these constituents in F. rhynchophylla was also optimized through extraction time, extraction solvent and extraction method using established method. From this study, extraction at $70^{\circ}C$ with the mixture of ethanol and water for more than 12 h was suggested to be good extraction condition for these constituents. Quantitation of nine constituents in different F. rhynchophylla samples was also successfully accomplished with the newly established method.

• Journal of Microbiology and Biotechnology
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• v.28 no.7
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• pp.1141-1146
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• 2018

2'-Fucosyllactose (2'-FL) is one of the most important human milk oligosaccharides and has several health benefits for infants. The levels of 2'-FL in breast milk or samples from other sources can be quantified by high-performance liquid chromatography. However, this method cannot be used for simultaneous detection of the target compound in numerous samples. Here, we developed a simple method for quantifying 2'-FL in a microplate format. The method involves two steps: (i) release of $\text\tiny{L}$-fucose from 2'-FL by ${\alpha}$-(1-2,3,4,6)-$\text\tiny{L}$-fucosidase and (ii) measurement of NADPH formed during the oxidation of $\text\tiny{L}$-fucose by $\text\tiny{L}$-fucose dehydrogenase. This method enables measurement of up to 5 g/l 2'-FL in 50 min using a 96-well microplate. The efficiency and simplicity of the proposed method make it suitable for the analyses of a large number of samples simultaneously.

• Bulletin of the Korean Chemical Society
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• v.33 no.7
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• pp.2163-2167
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• 2012

A rapid, specific, and reliable LC-MS/MS-based bioanalytical method was developed and validated in rat plasma for the simultaneous quantitation of amitriptyline and its metabolite nortriptyline. Chromatographic separation of these analytes was achieved on a Gemini C18 column ($50{\times}4.60mm$, $5{\mu}m$) using reversed-phase chromatography. The mobile phase was an isocratic solvent system consisting of 1% formic acid in water and methanol (10:90, v/v), at a flow rate of 0.2 mL/min. The analytical range was set as 0.1-500 ng/mL for amitriptyline and 0.08-500 ng/mL for nortriptyline using a $200{\mu}L$ plasma sample. The accuracy and precision of the assay were in accordance with FDA regulations for the validation of bioanalytical methods. The validated method was successfully applied to a pharmacokinetic study in six rats after oral administration of amitriptyline (15 mg/kg). This method allows laboratory scientists to rapidly determine amitriptyline and nortriptyline concentrations in plasma.

• Journal of Digital Convergence
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• v.10 no.6
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• pp.331-339
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• 2012

The easy and simple simultaneous analytical method of preservatives (BA, SA, DHA, MP, EP, IPP, PP, IBP and BP) was studied by more easily changing from method used in food and drug using HPLC with scherzo SM-C18 column. All presevatives were seperated successfully in mobile phase of 50 mM ammonium formate : 0.1% phosphoric acid (50:50 v/v%) and 50 mM ammonium formate : acetonitrile (30 : 70). Retention time of BA, SA, DHA, MP, EP, IPP, PP, IBP and BP was 7.74, 9.08, 12.57, 13.83, 21.62, 27.29, 28.20, 33.20 and 33.68 min, respectively. The calibration curves of BA, SA, DHA, MP, EP, IPP, PP, IBP and BP were linear over the concentration range of 5~80 ${\mu}g/mL$ with correlation coefficient of above 0.999. The limit of detection (LOD) and limit of quantitation (LOQ) of BA, SA, DHA, MP, EP, IPP, PP, IBP and BP were 0.52 and 1.58, 1.09 and 3.29, 1.00 and 3.03, 1.36 and 4.13, 1.26 and 3.83, 1.02 and 3.08, 1.11 and 3.37, 0.82 and 2.48, 0.85 and 2.59 ${\mu}g/mL$, respectively. The coefficients of variation for intra- and inter-day assay were 0.12~2.68 and 0.18~2.66%, respectively. The developed method showed good intra- and inter-day precision and accuracy. The preservatives used in mouthwashes were BA, MP and PP and were detected in 24 samples(86%) except for 4 samples and not showed significant difference in using dose of adult and children. In conclusion, the developed method can be useful for simultaneous analysis of preservatives in mouthwashes and these results suggest that could be applied to fundamental study and guideline on content of preservatives in mouthwashes.

• Journal of Food Hygiene and Safety
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• v.8 no.1
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• pp.9-15
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• 1993

In an attempt to quantitate and qualitate residual antibiotics and antibacterial agents in meat simultaneously, we studied a gas chromatography-mass spectrometry(GC/M8) analysis. For a simultaneous analysis of penicillin G, chloramphenicol and thiamphenicol in meat, a simple and rapid clean-up procedure including extraction with 0.01 M EDTA-2Na Mcilvaine buffer (pH 4.0), defatting with n-hexane, and elution with 0.01M-methanolic oxalic acid from Bond Elute $C_{18}$ cartridge, and quantitation by selected ion monitoring (SIM) mode after derivatization was performed. The recoveries (%) of penicillin G, chloramphenicol and thiamphenicol (CV, %) at 1 ppm fortification level were 63.5 (7.6), 76.3 (8.1) and 84.7 (2.0), and the detection limits of those were 0.6, 0.085 and $0.084\;\mu\textrm{g}$ beef, respectively. This method using 81M mode allows excellent detection and quantitation of residual antibiotics and antibacterial agents in meat. Moreover, confirmation by a full scan electron impact mass spectrum is possible if residual level in the sample in above 1 ppm.

• Bulletin of the Korean Chemical Society
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• v.33 no.2
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• pp.559-563
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• 2012

An analytical method for the simultaneous determination of veterinary medicines (amprolium and decoquinate) in cattle and chicken's muscle by HPLC/UV-vis was established. Samples were extracted by a HLB (Hydrophilic-Liphophilic Balance) cartridge with acetonitrile and methanol. Prior to HPLC injection, a mixture solvent (Water:MeOH, 1:1) was utilized as a reconstitution solvent. Chromatographic separation was achieved with a C18 column ($250{\times}4.6mm$, $5{\mu}m$) using gradient elution with 20 mM HFBA and MeOH:ACN (1:1.8). The calibration curves from the spiked blank matrix showed good linearity (above $r^2$=0.997) in the concentration range of $0.13-12.0mg\;kg^{-1}$. The relative recovery (accuracy) and limit of quantitation (LOQ) were in the range of 78.5-107.1% and $0.13-0.42mg\;kg^{-1}$, respectively. The developed method can be used to determine under the MRL (Maximum Residue Limits) levels of veterinary medicines in animal tissues.