Potentiometric determination of L‐dopa, carbidopa, methyldopa and aspartame using a new trinitrobenzenesulfonate selective electrode

Abstract

A selective PVC membrane electrode based on the ion-pair of cetylpyridinium (CP') and 2,4,6-trinitrobenzenesulfonate (TNBS-) as the electroactive species was developed. The electrode exhibits a rapid and Nernstian response to TNBS-from 5.0 x M at 25 k 0.I"C. The response is unaffected by the change of pH over the range 2-12. Selectivity coefficients for a larger number of organic and inorganic anions and sugars are given. The electrode has been successfully applied to the determination of L-dopa, carbidopa, methyldopa and aspartame in pure solutions and in their pharmaceutical formulations with a precision and accuracy of 0.9-1.3% without interference from excipients.

Studies of the Rate Constant of l-DOPA Oxidation and Decarboxylation by HPLC

“…In a formulation ) method that can separate the drug from its degradation products formed under various physico-chemical and enzymatic conditions. At present, a variety of analytical methods have been established for measuring L-DOPA levels in different sample matrices, such as spectrophotometry [13][14][15], flow injection analysis [16,17], spectrofluorimetry [18], chemiluminescence [19], potentiometry [20], voltammetry [21] and capillary electrophoresis [22], which, however, can hardly be considered simple, quick or inexpensive. Most of these techniques have suffered from diverse disadvantages with regard to specificity, complex sample preparation and long analysis time.…”

Differential pulse voltammetric determination of methyldopa using MWCNTs modified glassy carbon decorated with NiFe2O4 nanoparticles

“…Methyldopa is a competitive inhibitor of dopadecarboxylase, which metabolized Ldopa into dopamine [3,4]. Many analytical methods have been reported for determination of catecholamine drugs, such as methyldopa, in biological samples including spectrophotometry [5][6][7][8], fluorescence [9,10], high-performance liquid chromatography [11][12][13], chemiluminescence [14][15][16], gas chromatography [17], and potentiometry [18]. Some of these methods described above have disadvantages such as low sensitivity, long analysis times, and/or require expensive instruments.…”

EVALUATING THE ACCUMULATION TREND OF L-DOPA IN DARK-GERMINATED SEEDS AND SUSPENSION CULTURES OF Phaseolus vulgaris L. BY AN EFFICIENT UV-SPECTROPHOTOMETRIC METHOD

“…In this regard, various analytical methods such as HPLC technique with diode-array, fluorescence, electrochemical and UV-detection, 6-17 1 H-NMR analysis, 18 chemiluminescence, HPTLC, 22 gas chromatography, 23 radioimmunoassay, 24 titrimetric, 25 voltametric determination, 26 electrochemistry methods, 27 potentiometry, 28 LC-MS-MS, 29 and TLC have been developed. 30 However, most of these methods are complex and hence lack the simplicity needed for routine applications.…”