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Indirect determination of ephedrine in urine by differential pulse polarography
Author(s) -
Hernandez L.,
Zapardiel A.,
Bermejo E.,
Perez J. A.,
Chicharro M.,
Garijo M. J.
Publication year - 1997
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/elan.1140091518
Subject(s) - polarography , chemistry , hydrochloric acid , urine , chromatography , electrochemistry , detection limit , sodium nitrite , potassium , extraction (chemistry) , nitrosation , ephedrine , dropping mercury electrode , sodium sulfite , sodium , inorganic chemistry , electrode , biochemistry , organic chemistry , neuroscience , biology
The nitrosation of ephedrine and the electrochemical reduction of N ‐nitrosoephedrine were investigated by differential pulse polarography and have been optimized in order to attain the optimum analytical signal. Reduction of the N ‐nitrosoephedrine was carried out in one irreversible, diffusion‐controlled step using potassium chloride‐hydrochloric acid. In 0.1 M hydrochloric acid the N ‐nitrosoephedrine shows a well‐defined reduction peak at −0.77 V (vs. Ag/AgCl/ 3 M KCl). An indirect differential‐pulse polarographic method is described for the determination of ephedrine at levels higher than 2.5 μg per mL of urine. An extraction procedure with C 18 cartridge and a fast and easy nitrosation reaction with sodium nitrite in 0.2 M phthalate potassium hydrogen is also described. Determination of 5 μg/mL of N ‐nitrosoephedrine in urine samples of 4 mL was possible using the standard addition method, with a relative error of −4.0% and relative standard deviations no higher than 2.1%.
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