الفهرس 
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Abstract
The present work illustrates practical application for micro-determination of some drugs such as Enrofloxacin, Lomefloxacin and Ofloxacin usingc (HPLC) and spectrophotometric studies using acid dye reagent methods. These components are used as Antibacterial broad spectrum. The study containing three essential parts as follows:
Part I:
The introduction that gives a literature survey of the previous studies for the analysis of the studied drugs including high performance liquid chromatography and spectrophotometric studies.
Part II
The experimental part includes apparatus that used for the measurements and procedures for preparations of the drug solutions and reagents. It also contains the proposed high performance liquid chromatographic and spectrophotometric methods for determination of the studied drugs in pure form and dosage forms that analyzed. In addition, it contains pharmacopoeia) and official methods for analysis
of the studied drugs. Part III
Include the results and discussion of the high performance liquid chromatography and spectrophotometry using acid dye reagents for
ion-pair complex formation procedures for the determination of the
studied drugs. 111.1 High Performance Liquid Chromatography Methods
In this study, two different analytical techniques were used for
separation of the three investigated antibacterial drugs. A sensitive, selective, and accurate high performance liquid chromatography UV absorbance methods for determination of selected antibacterial drugs namely Enrofloxacin, Lomefloxacin and Ofloxacin either individual or in mixture were developed. Method A, the examined drugs were injected into a Nucleosil C18 column and eluted with a mobile phase consisting of acetonitrile and solution of potassium phosphate (pH 2.4) and flow rate 1.2 ml/min. Method B, the examined drugs were injected into a p Bondapack C18 column and eluted with a mobile phase consisting of acetonitrile and solution of mixture of ammonium acetate and sodium
perchlorate (pH 2.2) and flow rate 1.5 ml/min. The two developed methods revealed high linearity with correlation coefficient more than 0.999. Furthermore, the two methods were applied on the available
dosage forms of each component and the average assay approx. 100% and CV not more than 1%. The recovery of each studied component (individual and in mixture) between 98% and 102% with CV not more than 1%. Finally, the obtained results proved that the use of the two developed methods for routine analysis of the pharmaceutical compounds either in pure form or dosage forms.
111.2 Spectrophotometric Method
This part include the results and discussion of the spectrophotometric procedures for the determination of the studied drugs using acid dyes reagents such as phenol red, methyl red, cresol red, congo red and eriochrome black T. The proposed methods are based on coloured ion-
pair complex formation between the acid dyes and drugs which is extracted with organic solvents (chloroform, carbon tetrachloride, benzene and methylene chloride) and determination of the concentration by measuring the absorbance of the extracted complex against blank prepared by the some way. The following experimental variables are investigated;
•Effect of pH
•Effect of time and temperature
•Effect of extracting solvent
•Effect of reagent concentration
•Molecular ratio of the complex
•Sequence of addition
•Evaluation of the stability constants of the ion-pair complexes.
•Effect of the dosage form compositions
Furthermore, the three acid dye reagents were used at optimum conditions and found that Beer’s law is obeyed in concentration ranges (1-32, 1-26, 1-28, 1-36, 1-22 pgm1-1 for enrofloxacin), (1 -30,1-23, 1-30, 1-40, 1-20 pgm1-1 for lomefloxacin) and ( 1-34, 1-25, 1-25, 1-34, 1-18 pgml-1 for ofloxacin) with phenol red, cresol red, methyl red, congo red and eirochrom black T, respectively. For more accurate results,
Ringbom optimum concentration ranges are determined. Molar absorpitivity, Sandell sensitivity, detection and quantification limits are calculated. The stoichiometric ratios of studied drugs with phenol red are established using the molar ratio and continuous variation methods and found to be 1:1 for drug under consideration with phenol red. In order to determine the accuracy and precision of the proposed methods, solution containing three different concentrations of studied drugs are prepared and analyzed in six replicates. The recovery, relative standard deviation, the relative error and confidence limits are calculated. The proposed methods can successfully applied to determine the studied drugs in their dosage forms. The results obtained are compared statistically by Student’s t-test and variance ratio F-test
with the official method at 95% confidence level. The results showed that the t- and F- values are less than the critical value indicating that there is no significant difference between the proposed and official methods. Thus the proposed spectrophotmetric methods can be
applied in determination of the studied drugs in pure and in dosage forms.