FIA titrations of ephedrine in pharmaceutical formulations with a PVC tetraphenylborate tubular electrode.
A flow injection system for the titration of ephedrine in pharmaceutical products with potentiometric detection was developed. For this purpose a tetraphenylborate tubular electrode was constructed. The electrode was prepared without inner reference solution and with a PVC membrane based on tetrapentylammonium tetraphenylborate as ion exchanger and 2-nitrophenylphenyl ether as mediator solvent. Its operational characteristics were evaluated in a low dispersion manifold and compared with more conventionally shaped electrodes using the same sensor. In the pH range 2.5-11.5, the electrodes showed linear response between 3.8 x 10(-6) and 0.1 M with a slope of -56.4 mV/log[BPh4]. Ephedrine determinations in pharmaceutical products were carried out in a single channel manifold with a mixing chamber incorporated and using the tubular electrode as detector. Recovery rates of 98.6 +/- 2.5% were obtained in the analysis of tables, nasal drops and syrups with a sampling rate of about 60 h-1.
Alçada
M N
MN
CEQUP-Departamento de Química-Física, Faculdade de Farmácia, Universidade do Porto, Portugal.
Lima
J L
JL
Montenegro
M C
MC
D004566:Electrodes; D004809:Ephedrine / Q000032:analysis*; D017022:Flow Injection Analysis; D006863:Hydrogen-Ion Concentration; D007202:Indicators and Reagents; D011143:Polyvinyl Chloride; D011199:Potentiometry; D012996:Solutions; D013607:Tablets; D013775:Tetraphenylborate
D007202:Indicators and Reagents; D012996:Solutions; D013607:Tablets; D013775:Tetraphenylborate; D011143:Polyvinyl Chloride; D004809:Ephedrine