Improvement in precision of the liquid chromatographic-electrospray ionization tandem mass spectrometric analysis of 3'-C-ethynylcytidine in rat plasma.
During the development of the liquid chromatography with electrospray ionization-tandem mass spectrometry for the quantitative determination of 3'-C-ethynylcytidine (I) in rat plasma, ion suppression caused by the matrix components was observed for I and its structural analogue, 3'-C-ethylcytidine (II) as the internal standard. In the method initially designed, I/II peak area ratios varied according to the degree of matrix effect, which led to the poor precision of the assay. From the examination of the ion suppression behavior for I and II, it was assumed that this phenomenon is attributed to the difference in the retention time between I and II. Based on this assumption, therefore, the methanol content in the mobile phase was changed from 5 to 25% so as to make I and II the same retention time. As a result of this modification of the initial method, the precision expressed as relative standard deviation was improved from 5.2-16.2 to 2.7-4.2% in intra-assay and from 6.8-14.9 to 3.5-7.2% in inter-assay validations.
Kitamura
R
R
Pharmacokinetics Research Laboratory, Taiho Pharmaceutical Co., Ltd., Tokushima, Japan. r-kitamura@taiho.co.jp
Matsuoka
K
K
Matsushima
E
E
Kawaguchi
Y
Y
D000818:Animals; D002853:Chromatography, Liquid / Q000379:methods*; D003562:Cytidine / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000097:blood*; D013058:Mass Spectrometry; D015394:Molecular Structure; D051381:Rats; D015203:Reproducibility of Results
C103084:1-(3-C-ethynylribopentofuranosyl)cytosine; D003562:Cytidine