ABSTRACT
The electrochemical behavior of glipizide at the hanging mercury drop electrode (HMDE) was studied in B-R universal buffers of pH 1.7-11. The voltammograms exhibited a well-defined 4-electron irreversible cathodic peak which attributed to reduction of the two C=N of the pyrazine ring of glipizide molecule. Glipizide was found to has an interfacial adsorptive character onto the mercury electrode surface. A monolayer surface coverage of 1.02x10(-10)mol cm(-2) was estimated and hence each adsorbed glipizide molecule occupied an area of 1.63 nm(2) onto the mercury electrode surface. A simple and precise square-wave adsorptive cathodic stripping (SWAdCS) voltammetric procedure was described for quantification of bulk glipizide with a limit of detection of 1.5x10(-10)M and a limit of quantitation of 5x10(-10)M. The proposed procedure was successfully applied for quantitation of glipizide in its pharmaceutical formulation (Minidiab tablets) without interference from excipients.
Subject(s)
Glipizide/blood , Glipizide/chemistry , Hypoglycemic Agents/blood , Hypoglycemic Agents/chemistry , Buffers , Electrochemistry/methods , Electrodes , Humans , Hydrogen-Ion Concentration , Molecular Structure , Pharmaceutical Preparations/analysis , Pharmaceutical Preparations/blood , Pharmaceutical Preparations/chemistry , Reproducibility of Results , Sensitivity and Specificity , TabletsABSTRACT
The electroreduction of ethinylestradiol at the hanging mercury drop electrode in the Britton-Robinson universal buffer of pH 2-11 was studied and its interfacial adsorptive character onto the mercury electrode surface was identified. A validated simple, rapid, sensitive, specific, precise and inexpensive square-wave voltammetric procedure is described for the determination of ethinylestradiol following its accumulation onto a hanging mercury drop electrode in a Britton-Robinson universal buffer of pH 7. The optimal procedural conditions were: accumulation potential E(acc)=-0.7 V versus Ag/AgCl/KCl(s), accumulation duration=60s, pulse-amplitude=70 mV, scan increment=10 mV and frequency=120 Hz. Limits of detection (LOD) and quantification (LOQ) of 5.9x10(-10)M and 1.9x10(-9)M bulk ethinylestradiol, respectively, were achieved. The proposed procedure was successfully applied to the quantification of ethinylestradiol in pharmaceutical formulation (Ethinyl-oestradiol tablets) and in human serum and plasma without the necessity for sample pretreatments and/or time-consuming extraction or evaporation steps prior to the analysis. LOD of 8.7x10(-10)M and 3x10(-9)M and LOQ of 2.9x10(-9)M and 1x10(-8)M of ethinylestradiol were achieved in human serum and plasma, respectively.
Subject(s)
Ethinyl Estradiol/analysis , Pharmaceutical Preparations/chemistry , Adult , Electrochemistry/methods , Electrodes , Ethinyl Estradiol/blood , Female , Humans , Hydrogen-Ion Concentration , Mercury , Reproducibility of Results , TabletsABSTRACT
The electrochemical behavior of the antibiotic drug cefazolin sodium (CFZ) in Britton-Robinson buffers (pH 2-11) at the mercury electrode was studied by means of dc-polarography, cyclic voltammetry, controlled-potential coulometry and square-wave adsorptive stripping voltammetry techniques. A validated square-wave adsorptive cathodic stripping voltammetric procedure was described for the trace determination of cefazolin in bulk form up to limits of detection and quantitation of 2.6 x 10(-10)M and 8.6 x 10(-10)M, respectively. The method was successfully applied for determination of cefazolin in pharmaceutical preparation without the necessity for samples pretreatment or any time-consuming extraction or evaporation steps prior to the analysis.
Subject(s)
Anti-Bacterial Agents/analysis , Cefazolin/analysis , Mercury , Chemistry, Pharmaceutical , Electrochemistry , Electrodes , Hydrogen-Ion Concentration , Injections , Pharmaceutical Solutions , Polarography , Reference Standards , Reproducibility of ResultsABSTRACT
The polarographic behavior of amiloride hydrochloride has been studied in Britton-Robinson buffers of pH 1.9-11. In acidic medium at Ph< or =2, the dc-polarograms exhibited a single 4-electron cathodic irreversible wave, while at pH values >2, a second two-electron irreversible cathodic wave appeared at a more negative potential. The single or first wave may be attributed to the cleavage of the double bond of the -CH=NH of the imidino amide group with the release of NH(3). While the second wave may be due to the saturation of the C=O of the carboxamide moiety. A polarographic procedure of suffocate sensitivity for the determination of bulk amiloride drug in Britton-Robinson buffer at pH 2 is described. The calibration graph was obtained over the concentration range 2.5 x 10(-5) to 2.5 x 10(-4) M amiloride. The limits of detection (LOD) and quantitation (LOQ) of the procedure were 1 x 10(-5) and 3.3 x 10(-4) M bulk amiloride, respectively. Moreover, a differential-pulse adsorptive cathodic stripping voltammetric procedure has been described to assay of the drug at lower concentration levels. The optimal conditions were: E(acc) = -0.9V, t(acc)=30 s, scan rate=20mV, pulse-height=90 mV and Britton-Robinson buffer of pH 8. The calibration graph was obtained over the concentration range 2 x 10(-8) to 1 x 10(-6) M for bulk amiloride. Both procedures were successfully applied to the determination of amiloride in tablets without the necessity for sample pretreatment or any time-consuming extraction or evaporation steps prior to the drug analysis.
Subject(s)
Amiloride/analysis , Amiloride/chemistry , Mercury/analysis , Chemistry, Pharmaceutical , Electrochemistry , ElectrodesABSTRACT
Chlordiazepoxide is a sedative-hypnotic drug widely employed as a transquilizer and anti-depressant. Its electrochemical behavior in Britton-Robinson (B-R) buffers of pH 2-11 at a mercury electrode has been investigated using dc-polarography, cyclic voltammetry and controlled-potential coulometry. Polarograms of the drug in B-R buffers of pH 2-10 exhibited three 2-electron waves, while at pH>10, only a single 4-electron wave was observed. The first, second, and third waves in buffers of pH
Subject(s)
Chlordiazepoxide/blood , Chlordiazepoxide/chemistry , Hypnotics and Sedatives/blood , Hypnotics and Sedatives/chemistry , Mercury/chemistry , Chemistry, Pharmaceutical , Electrochemistry , Electrodes , HumansABSTRACT
Indomethacin is a non-steroidal anti-inflammatory drug possessing anti-pyretic and analgesic properties. A fully validated square-wave adsorptive cathodic stripping voltammetric procedure is described for determination of indomethacin. The procedure was based on the reduction of the C=O double bond of the drug molecule in Britton-Robinson buffer (pH 4) after its preconcentration onto the mercury electrode surface. The optimized conditions of the procedure were: frequency 120 Hz, scan increment 10 mV, pulse amplitude 50 mV, preconcentration potential -0.9 V (vs. Ag/AgCl/KCl(s)) and preconcentration time 90 s. The proposed procedure was successfully applied for determination of the drug in tablets and human serum with good recoveries. The limits of detection in bulk form and human serum were 6.7 x 10(-10) mol L(-1) and 8.1 x 10(-10) mol L(-1), respectively.