A rapid and sensitive column-switching semi-micro high-performance liquid chromatography method was developed for the direct analysis of tiropramide in human plasma. The plasma sample (100 microl) was directly injected onto Capcell Pak MF Ph-1 precolumn where deproteinization and analyte fractionation occurred. Tiropramide was then eluted into an enrichment column (Capcell Pak UG C(18)) using acetonitrile-potassium phosphate (pH 7.0, 50 mM) (12:88, v/v) and was analyzed on a semi-micro C(18) analytical column using acetonitrile-potassium phosphate (pH 7.0, 10 mM) (50:50, v/v). The method showed excellent sensitivity (limit of quantification 5 ng/ml), and good precision (C.V.
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http://dx.doi.org/10.1016/s0731-7085(02)00570-8 DOI Listing Publication Analysis
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Food Chem
December 2024
Shandong Provincial Key Laboratory of Biochemical Engineering, College of Biological Engineering, Qingdao University of Science and Technology, Qingdao 266042, China. Electronic address:
This study aimed to explore the relationship between hypoxanthine (Hx) levels and freshness indicators in three kinds of fish samples during storage for 7 days at 4 °C to determine the Hx levels indicating freshness. The total volatile basic nitrogen (TVBN) was tested using the semi-micro Kjeldahl method, and Hx level and K value were measured using high-performance liquid chromatography (HPLC). During storage, Hx levels, TVBN, and K values increased, and distinct patterns were observed between Hx and TVBN in three fish samples.
View Article and Find Full Text PDFAnal Sci
June 2021
Department of Molecular and Material Sciences, Kyushu University.
A detection system consisting of a photothermal heterodyne interferometer (PHI) combined with semi-micro HPLC (high-performance liquid chromatography) has been designed and investigated. An ultraviolet (UV) or deep-UV laser emitting at 375 or 213 nm, respectively, was used for the excitation of nitro-polycyclic aromatic hydrocarbons (NPAHs) and amino acids. A photothermally induced change in the refractive index of the solvent causes an optical phase difference between two arms of the interferometer, one beam passing through the photoexcited region and another used as a reference, which was sensitively detected with the PHI.
View Article and Find Full Text PDFRapid Commun Mass Spectrom
October 2011
Laboratory of Analytical and Bio-Analytical Chemistry, School of Pharmaceutical Sciences, and Global COE Program, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan.
With Boc-Asn-GlcNAc as a basic structure, four permanently positively charged kinds of new acceptors (GP-Boc-Asn-GlcNAc, GT-Boc-Asn-GlcNAc, HMP-Boc-Asn-GlcNAc, MPDPZ-Boc-Asn-GlcNAc) and five kinds of similar structure acceptors (2-PA-Boc-Asn-GlcNAc, 3-PA-Boc-Asn-GlcNAc, 4-PA-Boc-Asn-GlcNAc, HP-Boc-Asn-GlcNAc, PDPZ-Boc-Asn-GlcNAc) were synthesized as acceptors for the resolution of oligosaccharides in glycopeptides. The synthesized acceptors enzymatically reacted with Disialo-Asn (donor) in the presence of Endo-M. The reaction yields of each transglycosylation product were not obvious, because we do not have all the authentic Disialo-Asn-Boc-acceptors.
View Article and Find Full Text PDFJ Chromatogr B Analyt Technol Biomed Life Sci
April 2011
Department of Analytical Chemistry, School of Pharmacy, Tokyo University of Pharmacy and Life Sciences, Tokyo, Japan.
A simple method has been developed for the simultaneous determination of lathosterol and cholesterol by high-performance liquid chromatography with electrochemical detection (HPLC-ECD). Lathosterol was found to be electrochemically oxidized and its current peak height was linearly related to the amount of lathosterol injected, ranging from 0.15 μmol/L to 300 μmol/L (r=0.
View Article and Find Full Text PDFJ Chromatogr B Analyt Technol Biomed Life Sci
December 2010
Department of Bio-analytical Chemistry, Faculty of Pharmaceutical Sciences, Niigata University of Pharmacy and Applied Life Sciences, 265-1 Higashijima, Akiha-ku, Niigata, Niigata 956-8603, Japan.
A method for the simultaneous determination of pregnenolone and 17α-hydroxypregnenolone by high-performance liquid chromatography with an immobilized cholesterol oxidation enzyme reactor was developed. Pregnenolone and 17α-hydroxypregnenolone were converted to progesterone and 17α-hydroxyprogesterone, respectively, by the immobilized enzyme packed into the reactor column, and could thus be monitored by UV absorption at 240 nm. The calibration curves for pregnenolone and 17α-hydroxypregnenolone were linear in the range of 0.
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