A simple analytical method involving the use of a monolithic silica disk-packed spin column and HPLC-ECD for determination of l-DOPA in plasma of patients with Parkinson's disease

Makoto Tsunoda,Takao Tsuda,Masaaki Hirayama,Kinji Ohno

doi:10.1039/c3ay40934a

Abstract

L-DOPA (L-3,4-dihydroxyphenylalanine) is commonly used in the treatment of Parkinson's disease. Monitoring the concentration of L-DOPA in human plasma will enable dose optimization, but is rarely performed because current quantification methods are tedious and time-consuming. In this study, a simple method for the determination of L-DOPA in the plasma of patients with Parkinson's disease was developed. A monolithic silica disk-packed spin column with a phenylboronate moiety, which forms stable anionic complexes with the cis-hydroxyl groups of L-DOPA, was used to extract L-DOPA from plasma with extraction recoveries exceeding 90%. The extracted L-DOPA was then separated on a reversed-phase column and detected electrochemically with a boron-doped diamond electrode. The method, which has a limit of detection of 10 fmol, was then successfully applied for the determination of L-DOPA in the plasma of healthy volunteers and patients with Parkinson's disease.

Highlights

Parkinson's disease (PD) is a common neurodegenerative disease that affects 0.3% of the population over the age of 50
The drug L-DOPA (L-3,4-dihydroxyphenylalanine) is currently the most effective treatment option for PD, but continuous administration of L-DOPA generally leads to narrowing of the therapeutic window.[2]
If the concentration of L-DOPA falls below a certain threshold, PD symptoms can intensify to where the patients cannot move, which is known as wearing-off or the on–off phenomenon

Summary

Analytical Methods

A simple analytical method involving the use of a monolithic silica disk-packed spin column and HPLC-ECD for determination of L-DOPA in plasma of patients with Parkinson's disease. L-DOPA (L-3,4-dihydroxyphenylalanine) is commonly used in the treatment of Parkinson's disease. A simple method for the determination of L-DOPA in the plasma of patients with Parkinson's disease was developed. A monolithic silica disk-packed spin column with a phenylboronate moiety, which forms stable anionic complexes with the cis-hydroxyl groups of L-DOPA, was used to extract L-DOPA from plasma with extraction recoveries exceeding 90%. The method, which has a limit of detection of 10 fmol, was successfully applied for the determination of L-DOPA in the plasma of healthy volunteers and patients with Parkinson's disease

Introduction

Method validation

Results and discussion

Conclusion