Determination of L-3,4-dihydroxyphenylalanine in blood by high-performance liquid chromatography after solvent extraction.
The use of high-performance liquid chromatography combined with solvent extraction for sample purification is described for the determination of L-3,4-dihydroxyphenylalanine in blood plasma. It is extracted into n-hexanol via complexation of its catechol moiety with diphenyl borate and ion-pair formation of its carboxylic group with tetrapentylammonium ion in an alkaline buffer. Under optimal extraction conditions, L-3,4-dihydroxyphenylalanine and 3,4-dihydroxybenzylamine used as an internal standard are extracted from blood plasma by a simple procedure and in a short time and then separated by reversed-phase ion-pair chromatography. The analytical recovery (100.8%) and reproducibility (coefficient of variation = 2.3% for n = 6) from plasma samples are good enough for routine analysis. L-3,4-Dihydroxyphenylalanine levels in blood can be monitored by this method after oral intake of the substance.
Tsuchiya
H
H
Department of Dental Pharmacology, Asahi University School of Dentistry, Gifu, Japan.
Hayashi
T
T
D001881:Borates; D002851:Chromatography, High Pressure Liquid; D002852:Chromatography, Ion Exchange; D004298:Dopamine / Q000031:analogs & derivatives / Q000097:blood; D004305:Dose-Response Relationship, Drug; D006801:Humans; D007980:Levodopa / Q000097:blood*; D008297:Male; D012997:Solvents; D013050:Spectrometry, Fluorescence
D001881:Borates; D012997:Solvents; C022133:3,4-dihydroxybenzylamine; D007980:Levodopa; D004298:Dopamine