A Novel Spectrophotometric Method for the Determination of Levodopa with the Detection System of Potassium Ferricyanide‐Fe(III)

Abstract

In this paper, a novel method has been established to determine levodopa with the detection system of potassium ferricyanide‐Fe(III). In the presence of potassium ferricyanide, it has been demonstrated that Fe(III) is reduced to Fe(II) by levodopa at pH 4.0. In addition, the in situ formed Fe(II) reacts with potassium ferricyanide to form soluble prussian blue (KFeIII[FeII(CN)6]). Beer's law is obeyed in the range of levodopa concentrations of 0.01–4.00 μg mL−1 at the maximal absorption wavelength of 735 nm. The linear regression equation is A = 0.0082 + 0.61365 C (μg mL−1) with a correlation coefficient of 0.9996. The detection limit (3σ/k) is 9 ng mL−1, and R.S.D. is 0.73% (n = 11). Moreover, the apparent molar absorption coefficient of indirect determination of levodopa is 1.2 × 105 Lmol−1cm−1. The parameters with regard to determination are optimized, and the reaction mechanism is discussed. This method has been successfully applied to determine levodopa in pharmaceutical, serum and urine samples. Analytical results obtained with this novel assay are satisfactory.

Determination of Picogram Levels of Levodopa in Pharmaceutical Preparations and Biofluids by Flow-Injection Chemiluminescence

“…Various methods have been developed for the determination of L-dopa, including high performance liquid chromatography [2], gas chromatography [3], electrochemistry [4], UV-Vis spectrophotometry [5], and flow-injection chemiluminescence (FI-CL) [6,7], etc. Compared with other methods, FI-CL offers the amazing advantages of ultra sensitivity, instrumental simplicity, and sampling efficiency in the different science fields.…”