An improved method for the determination of S-Carboxymethyl-L-cysteine in biological fluids with precolumn derivatization and on-line clean-up |
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Authors: | P. Guinebault C. Dubruc A. Haddouche C. Colafranceschi G. Bianchetti |
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Affiliation: | (1) Synthelabo Recherche (L.E.R.S.), 58 rue de la Glacière, F-75013 Paris, France |
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Abstract: | Summary In order to follow levels of S-Carboxymethyl-L-cysteine in biological fluids for a period as long as three half-lives after drug administration during pharmacokinetic studies, an improved method for its determination had to be developed. Like the previous one, this method uses a protein precipitation step followed by an O-Phthalaldehyde derivatization step and then an HPLC on-line clean-up. This latter was obtained by means of a switching valve system, including a Nucleosil CN 5 m (3 cm × 4.6 mm i.d.) precolumn and a Spherisorb ODS 5 m (15 cm×4.6 mm i.d.) analytical column. The sensitivity limit was improved to 0.1 g/ml in plasma samples and 0.2 g/ml in urine samples.This method was applied in studies comparing single (0.75 g) and repeated (0.75 g tid) oral administration of the drug to 30 elderly patients and 20 healthy volunteers. Results showed that the half-life was 40% longer in elderly patients than in healthy volunteers, and that area under the plasma concentration versus time curve (AUC) values in elderly patients were twice those obtained with young subjects. |
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Keywords: | Column liquid chromatography Determination of S-Carboxymethyl-L-cysteine Precolumn derivatization HPLC on-line clean-up |
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