• Proceedings of the PSK Conference
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• 2001.04a
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• pp.183.1-183.1
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• 2001

• Proceedings of the PSK Conference
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• 2000.04a
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• pp.201.1-201.1
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• 2000

• Proceedings of the PSK Conference
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• 2002.04a
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• pp.178.1-178.1
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• 2002

• Archives of Pharmacal Research
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• v.27 no.9
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• pp.901-905
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• 2004

A rapid, sensitive and selective hydrophilic interaction liquid chromatography-tandem mass spectrometric(HILIC-MS/MS) method for the determination of tiapride in human plasma was developed. Tiapride and internal standard, metoclopramide were extracted from human plasma with dichloromethane at basic pH and analyzed on an Atlantis HILIC silica column with the mobile phase of acetonitrile-ammonium formate (190 mM, pH 3.0) (94：6, v/v). The ana-Iytes were detected using an electrospray ionization tandem mass spectrometry in the multi-ple-reaction-monitoring mode. The standard curve was linear (r＝0.999) over the concentration range of 1.00-200 ng/mL. The coefficient of variation and relative error for intra- and inter-assay at three QC levels were 6.4∼8.8％ and -2.0∼3.6％, respectively. The recoveries of tiapride ranged from 96.3 to 97.4％, with that of metoclopramide (internal standard) being 94.2％. The lower limit of quantification for tiapride was 1.00 ng/mL using 1 00 $\mu$L of plasma sample.

• BMB Reports
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• v.43 no.11
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• pp.761-765
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• 2010

Salivary testosterone levels in Korean adults were quantitatively measured for the first time by liquid chromatography-electrospray-tandem mass spectrometry (LC ESI MS/MS). Salivary testosterone was separated on a multiple reaction monitoring (MRM) chromatogram within 7 min. The LC ESI MS/MS assay was validated over the linearity range of 0.01-2.00 ng/ml (r=0.99987) using testosterone-$d_3$ as an internal standard. The lower limit of quantification (LOQ) was 0.01 ng/ml. The intra- and inter-assay precisions were 1.54% to 4.09% and 0.96% to 4.29%, respectively. The mean recovery was 93.32% (range 88.43-98.05%). The validated assay was then applied to measure the salivary testosterone levels of Korean adults. In men, the salivary testosterone level collected between 9：00-11：00 am was approximately 2.8 times higher than that in women (P < 0.0001). Salivary testosterone levels in both sexes negatively correlated with age. The present assay would also be useful in measuring salivary testosterone levels in clinical laboratories.

• Biomolecules & Therapeutics
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• v.17 no.2
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• pp.188-198
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• 2009

This work was conducted to investigate the effect of bisphenol A (BPA) on estradiol (E2) 2-and 4-hydroxylase activities in the liver, kidney and lung tissues of male and female rats. After intraperitoneal administration of BPA to male and female rats for 4 days at 0, 10, and 50 mg/kg, the conversion of the substrate for hepatic and extra-hepatic enzyme activities was measured by GC/MSD. The result showed decreases of body and organ weights at 50 mg/kg BPA of male and female rats. Male hepatic E2 2-hydroxylase activity was inhibited by 68% at 10 mg/kg and by 82% at 50 mg/kg BPA. Female hepatic E2 2-hydroxylase activity was decreased by 46% at 10 mg/kg and by 56% at 50 mg/kg to the control. E2 4-hydroxylase was inhibited by 57 and 57% at 10 mg/kg and 54 and 78% at 50 mg/kg in liver of female and male, respectively. The urinary excretion rate of 2-hydroxyestradiol (2-OHE), androsterone and testosterone in urine of female rats with 50 mg/kg BPA were decreased significantly. The results showed that 50 mg/kg BPA was decreased E2 2-and 4-hydroxylase activities in liver, but not in other tissues. The urinary excretion rates of 2-OHE, androsterone and testosterone were also decreased. In liver, estrogenic enzyme activity were higher in male than female. These results suggest that BPA can disrupt estrogen metabolism by suppressing E2 2-and 4-hydroxylase activities in the liver of male and female rats.

• Analytical Science and Technology
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• v.13 no.6
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• pp.1089-1096
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• 2000

• Proceedings of the Korea Environmental Mutagen Society Conference
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• 2004.05a
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• pp.33-34
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• 2004

• Proceedings of the PSK Conference
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• 2000.04a
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• pp.219.1-219.1
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• 2000

• Bulletin of the Korean Chemical Society
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• v.31 no.5
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• pp.1149-1154
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• 2010

Liquid chromatography/mass spectrometry using isotope dilution method has been established as a primary method for the measurement of cortisol in human serum. Verification of this method was accomplished by the participation in Consultative Committee for Amount of Substance-Metrology in Chemistry (CCQM) pilot study. Two levels of cortisol certified reference materials were prepared and certified by the established method. They were used as sample materials for the proficiency testing. The expanded uncertainty in the measurement of cortisol in human serum was approximately 1.2% at 95% confidence level. The results of the proficiency testing showed a good precision among the participants, but some bias to the certified values. This means that commercial field laboratories should keep traceability chain to SI unit through available reference measurement procedures and/or available reference materials.