Chemical and Pharmaceutical Bulletin
Online ISSN : 1347-5223
Print ISSN : 0009-2363
ISSN-L : 0009-2363
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Determination of ppb Levels of Tryptophan Derivatives by Capillary Electrophoresis with Homogeneous Liquid–Liquid Extraction and Sweeping Method
Yoshitaka TakagaiShukuro Igarashi
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2003 Volume 51 Issue 4 Pages 373-377


Tryptophan (Trp) derivatives were selectively separated from 24 kinds of amino acid mixture solutions. Capillary electrophoresis (CE) with UV detection using the described pretreatment system was able to separate and determine 4 kinds of Trp derivatives: 5-hydroxy L-tryptophan, 5-methyl L-tryptophan, 1-methyl L-tryptophan and L-tryptophan. The pretreatment system used a combination of a homogeneous liquid–liquid extraction and a sweeping method, the two are different kinds of powerful preconcentration/separation methods. Trp derivatives were thus separated by two different separation systems. First, these derivatives were selectively extracted at 57—100% by a homogeneous liquid–liquid extraction; secondly, they were respectively separated by micellar electrokinetic chromatography (MEKC) with a sweeping effect. The detection limits following complete separation of the Trp derivatives were 10−8 mol l−1 levels, respectively. The proposed method provided a more than 10-fold the improvement in sensitivity compared with fluorescence labeling/fluorophotometric analysis; the proposed method was also applied to the component analysis of nutritious medicine.

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© 2003 The Pharmaceutical Society of Japan
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