Internal solid contact sensor for the determination of doxycycline hydrochloride in pharmaceutical formulation

Quantitative Analysis of Methacycline Hydrochloride by Direct Potentiometry Using the Internal Solid Contact Sensor

“…10 The procedures of pretreating a substrate electrode (Pt or GC) surface and of modifying PPy or Pan film on substrate in a three electrode-cell, i.e. disc electrode used as the working electrode, SCE as reference electrode and platinum wire electrode as counter electrode, by repeating potential scan method, and of preparation of ISCS by dipping-coating procedures are the same as described by Sun et al 5,6 The following conditions are used for preparation of PPy or Pan film on substrate for a sensor. Evaluation of the comprehensive quality of sensor 5,9 The value of CQI for a given sensor is caculated using the following equation: CQI = ΣfiPi, where fi denotes a weighting factor whose values are 0.38 for f1, 0.30 for f2, 0.22 for f3 and 0.10 for f4, respectively, and Pi denotes the devoting of one of performances, which include S (mV/decade), LR (M), LD (M) and T (s) which is defined as the time needed for the sensor to reach a stable potential value after a concentration step from 10 -4 to 10 -3 M of the primary ion, 11 to the value of CQI, and the values can be calculated from the following formula: P1 = S/20, P2 = lg[LR]upper limit -lg[LR]lower limit, P3 = aLDmax/LDi, P4 = b/Ti.…”

“…Previous experimental investigations 5,6 have found that the conditions/parameters of electropolymerization for pyrrole (or aniline) could affect the response performances of ISCSs to some extent.…”

“…1, so the following electropolymerization parameters of pyrrole are the best selected: 0.25 M pyrrole, 1 M KCl, repeating scan times 15 (or 20 times for GC) and scan potential range from -0.1 to +0.7 V. It is of interest that the electropolymerization conditions are consistent with the optimized conditions of the preparation of PPy for the two sensors Pt/Ppy/PVC(OTC-PT) 5 and Pt/Ppy/PVC(DC-TPB). 6 For the preparation of PAn film, the optimized conditions of electropolymerization for the preparation of Pt/PAn/PVC(DC-TPB) 6 are directly applied as follows: 1.0 M aniline, 1.0 M HCl, repeated scan times 15 (or 20) times for Pt (or GC) and scan potential range from -0.1 to +0.8 V.…”

“…3,4 Therefore, searches for new analytical methods or techniques for the determination of tetracyclines in various samples have attracted a great deal of attentions. 2,5,6 For the determination of MC·Cl, some pharmacopoeias recommend high performance liquid chromatography (HPLC) 7,8 and antibiotics-microbial assay. 7 A few analytical methods including HPLC, spectrophotometry and phosphorimetry for the determination of MC·Cl in pharmaceutical analysis have been reported in the literature.…”

Weighting Factor in Calculation of Comprehensive Quality Index and Optimization of PVC Membrane Composition for Ion Selective Electrode

“…1.0 Â 10 22 -1.0 Â 10 26 M standard solutions of DC.Cl were also prepared using the same procedures described elsewhere. [6,11] …”