الفهرس 
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Abstract
In this study different analytical techniques were used for the separation of the investigated NSAIDs:
1-A sensitive, selective and accurate high-performance liquid chromatography (HPLC) UV- absorbance and high-performance liquid chromatography-mass spectrometry (LC-MS) assay for the determination of selected non-steroidal anti-inflammatory drugs (NSAIDs), namely salicin (SAL), salicylic acid (SAL.A), tenoxicam (TEN), ketorolac (KET), tolmetin (TOL), piroxicam (PIR), naproxen (NAP), flurbiprofen (Flu), diclofenac (DIC), ibuprofen (IBU), either individual or in mixtures, was developed. The examined drugs were injected onto a Spherisorb C18 column and and eluted with a mobile phase consisting of acetonitrile (ACN) and 20 mM ammonium acetate (pH 3.7) at flow rate of 1 ml/min.
The p-HPLC approach was based on the use of capillary columns and mobile phase at flow rate of 2 pl/min. In this coherence a fused silica capillary was packed with ProntoSil C18 and stabilized by encapsulation with poly(styrene-divinylbenzene).
The comparison between HPLC-UV, LC-MS and p-HPLC revealed similar limits of detection for p-HPLC and LC-MS, but lowest consumption of mobile phase and sample when using p-HPLC-UV (2 pl/min flow rate, 0.5 pl injection volume). All three determination methods revealed high linearity with correlation coefficient > 0.9600.
Finally, the obtained results approve the use of the developed p-HPLC-UV for routine analysis of the pharmaceutical compounds investigated.
2-The study has been performed to evaluate the use of micellar electrokinetic chromatography (MEKC), a mode of capillary electrophoresis (CE) as analytical technique in pharmaceutical analysis in separation of studied NSAIDs. Valuable information was gathered and optimum conditions were defined, which resulted in fast elution with baseline-separated peaks. Capillary electrophoresis was conducted by using a separation buffer consisting of 20 mM Na2HPO4, 20 mM B-cyclodextrin and 50 mM SDS at pH 9.0, an applied voltage of 25 kV and a temperature 25-26°C. The analysis time is 8 min and the detection limits between 0.5-5.0 pg/ml. The MEKC method was validated according to the recommended validation procedures of the International Conference of Harmonization. The validation was performed on
commercially available formulations (tablets, capsules and injections) to verify the suitability of the method.
3- The production of pharmaceutical formulations of the investigated compounds involve stability studies to guarantee high quality products. The stability of aceclofenac (AC) was investigated using a high-performance liquid chromatography (HPLC) procedure, consisting of a Spherisorb C18 column and 20 mM ammonium acetate (pH 3.7) and acetonitrile as mobile phase. Working with a gradient system at a flow rate of 1 ml min-1, the developed method was specific, accurate and reproducible. The stability of AC was performed in 0.1 M hydrochloric acid, phosphate buffer (pH-7.5) and water/ethanol (1:1). AC was found to undergo fast hydrolysis in 0.1 M hydrochloric acid solution. The decomposition of the investigated drug followed a first order kinetics. The degradation rate constant was found -at 0.0183 and degradation half-life at 16.45 hr at 25°C. In comparison AC was more stable in physiological phosphate buffer (pH 7.5), whereas the degradation rate constant and degradation half-life were 0.0028 h-land 107.33 h, respectively.
In a second approach the production of degradation products under different pHs (0.1M HCI, 0.1M Na0H) was investigated by LC-MS. Interestingly degradations patterns of low and high pH were very similar with ident signals at m/z 296 (diclofenac) and at m/z 278 (1-(2,6-dichlorophenyI)-2-indolinone), but with an additional signal at m/z 309 (diclofenac methyl ester) occurring only after alkaline hydrolysis.
Finally, this method permits detection and quantitation of aceclofenac in the presence of its degradation products, giving also information about nnass to charge ratios and possible degradation pathways.