caa a22 4500 465746586 CHVBK 20180323111822.0 cr unu---uuuuu 170327e19900101xx s 000 0 eng 10.1007/BF00322550 doi (NATIONALLICENCE)springer-10.1007/BF00322550 Issopoulos Prodromos Laboratory of Analytical Chemistry, Department of Inorganic and Analytical Chemistry, University of Ioannina, Ioannina, Greece aut High-sensitivity spectrophotometric determination of trace amounts of Levodopa, Carbidopa and α-Methyldopa [Elektronische Daten] [Prodromos Issopoulos] Summary: A simple, sensitive and accurate spectrophotometric method for the determination of Levodopa (LVDA)(I), Carbidopa (CBDA)(II) and α-Methyldopa (α-MDA)(III) at the ppb level has been developed. This method is based on the oxidation of (I), (II) and (III) by Fe(III), using a Fe(III)-o-Phenanthroline mixture and is followed by the formation of a highly stable orange-red coloured tris-complex [Fe(II)-(o-Phenanthroline)3]2+ in a moderate acidic medium (pH=5.0±0.2) which exhibits an absorption maximum at λ=510 nm. The apparent molar absorptivities were 1.26×105, 1.02×105 and 1.29×105 l mol−1 cm−1 and the Sandell's sensitivities were 1.57, 2.20 and 1.60 ng cm−2 for (I), (II) and (III), respectively. Beer's law is obeyed in a concentration range from 50 to 2500 ppb for (I) and (III) and from 100 to 4000 ppb for (II). The slope and the intercept of the regression lines for each of these drugs were calculated with correlation coefficients of 0.9999 for (I) and (III) and 0.9998 for (II). The results obtained from the determination of the drugs studied, using both the described procedure and the corresponding official method, were statistically compared by means of the Student's t-test and by the variance ratio F-test, and no significant difference was observed. Springer-Verlag, 1990 Fresenius' Journal of Analytical Chemistry Springer-Verlag 336/2(1990-01-01), 124-128 0937-0633 336:2<124 1990 336 216 https://doi.org/10.1007/BF00322550 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00322550 text/html Onlinezugriff via DOI NATIONALLICENCE 100 1- Issopoulos Prodromos Laboratory of Analytical Chemistry, Department of Inorganic and Analytical Chemistry, University of Ioannina, Ioannina, Greece aut NATIONALLICENCE 773 0- Fresenius' Journal of Analytical Chemistry Springer-Verlag 336/2(1990-01-01), 124-128 0937-0633 336:2<124 1990 336 216 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer