Modified high-performance liquid chromatography with electrochemical detection method for plasma measurement of levodopa, 3-O-methyldopa, dopamine, carbidopa and 3,4-dihydroxyphenyl acetic acid

Determination of levodopa in human plasma by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS): application to a bioequivalence study

“…In addition, the short retention time and good resolution of the analyte and internal standard under HPLC-MS/MS conditions have the advantage of high-throughput in the analysis compared to recent studies in the literature using a similar extraction method. 1,6,9,19,20 The extraction method used was considered satisfactory since higher peak symmetry and sharper signals by acid amount added were achieved and short analysis time, without decreasing the signal intensity of levodopa (Figure 1b) or of the internal standard carbidopa (Figure 2b).…”

“…21 In this method, no additive was used for pH adjustment (neutralization) or for the precipitation of perchlorate in the extraction stage, in contrast to findings in the literature. 1,11 Therefore, the choice of the column was based on its strength, according to the analytical chromatographic method used and the ability to tolerate the injection of samples processed with perchloric acid.…”

“…1,11,[19][20][21][22] Protein precipitation with perchloric acid 0.4 M was applied to prepare plasma samples because it was simple to perform, fast, easily reproducible and provides a high recovery of the analyte under our experimental conditions (Table 2).…”

“…1,2 The motor features, such as bradykinesia, resting tremor, rigidity, gait and postural changes, are the major features of PD. 3 Levodopa (LVP) provides rapid and effective control of motor symptoms in virtually all PD patients and since its introduction has dramatically improved survival and quality of life for people with PD and is considered the gold standard of PD pharmacotherapy.…”

“…4,7,8 Measurements of LVP and its metabolites in blood have been crucial for development of these strategies by clarifying the role of systemic pharmacokinetics in clinical response. 1 Several methods have been developed to determine LVP and its major metabolite 3-O-methyl dopa in biological fluids. However, most methods of LVP and 3OMD quantitation were carried out by using high-performance liquid chromatography with electrochemical detection (HPLC-EC).…”