• Bulletin of the Korean Chemical Society
• /
• v.18 no.5
• /
• pp.463-464
• /
• 1997

• Bulletin of the Korean Chemical Society
• /
• v.18 no.5
• /
• pp.475-478
• /
• 1997

(3R,4R)-4-Acetoxy-3-[(1'R-tert-butyldimethylsilyloxy)ethyl]-2-azetidinone, one of the best synthons for carbapenems and penems was efficiently synthesized from readily available L-threonine via double azetidinone ring formation.

• Korean Architects
• /
• no.5 s.218
• /
• pp.7-23
• /
• 1987

• The Korean Chronic Disease News
• /
• no.294
• /
• pp.9.2-9.2
• /
• 2005

• The monthly packaging world
• /
• s.112
• /
• pp.169-171
• /
• 2002

• KPRC NEWS
• /
• no.10
• /
• pp.16-17
• /
• 2007

• Analytical Science and Technology
• /
• v.19 no.6
• /
• pp.519-528
• /
• 2006

An analytical method for the determination of thyroid hormones in urine samples has been studied by using solid-phase extraction and high-performance liquid chromatography/diode array detector/electro-spray mass spectrometry. Seven thyroid hormones were successfully separated by gradient elution on the reverse phase Hypersil ODS column (4.6 mm I.D., 100 mm length, particle size $5{\mu}m$) with ammonium formate buffer and acetonitrile, and UV spectra and mass fragment could be confirmed. The extraction recoveries of thyroid hormones in the urine samples (pH 3) were in the range of 89.0-113.1% with solid-phase extraction by C18, followed by elution with 4 ml of methanol/ammonium hydroxide (9 : 1). The calibration curves showed good linearity with the correlation coefficients ($r^2$) varying from 0.992 to 0.998 and the detection limits of all analytes were obtained in the range of 2-4 ng/ml (3.8-13.0 pmol/ml).

• Analytical Science and Technology
• /
• v.20 no.5
• /
• pp.424-433
• /
• 2007

An analytical method for the determination of thyroid hormones in plasma samples has been studied by solid-phase extraction and high-performance liquid chromatography/diode array detector (DAD)/electrospray ionization (ESI)-mass spectrometer. Seven thyroid hormones were successfully separated by gradient elution on the reverse phase Hypersil ODS column (4.6 mm I.D., 250 mm length, particle size $5{\mu}m$) with ammonium formate buffer and acetonitrile. In addition, these compounds were confirmed by UV spectra and ESI-mass Spectra. The extraction recoveries of thyroid hormones in the plasma sample (at pH 3) were in the range of 74.5-115.7 % with solid-phase extraction by C18, followed by elution with 4 mL of methanol. The calibration curves showed good linearity with the correlation coefficients ($r^2$) varying from 0.9939 to 0.9978 and the detection limits of all analytes were obtained in the range of 20-50 ng/mL (38.1-162.8 pmol/mL). As a result, thyroxine was found in the range of 50.98-112.97 ng/mL in normal plasma samples.