This study describes the development and validation of high performance thin layer chromatographic (HPTLC) method for the simultaneous estimation of Emtricitabine (EMT), Rilpivirine (RPV) and Tenofovir disoproxil fumarate (TFV) in combined dosage form. Chromatographic separation of these drugs was performed on aluminum plates precoated with silica gel 60 F254 as the stationary phase using solvent system consisted of chloroform: ethyl acetate: methanol: glacial acetic acid (5:2:1:0.1 v/v/v/v). The densitometric analysis was carried out in absorbance mode at 272 nm. The drugs were satisfactorily resolved with Rf values of 0.28 ± 0.02, 0.70 ± 0.02 and 0.52 ± 0.04, respectively. The method was validated according to the International Conference of Harmonization (ICH) guidelines. The calibration curves were linear over the (r 2 > 0.999) concentrations range from 600-2400 ng band -1 for Emtricitabine, 50-300 ng bands -1 for Rilpivirine and 600-3600 ng band -1 for Tenofovir disoproxil fumarate. The method showed accuracy of 100.01%, 100.32% and 100.14% and percentage assay of 99.91%, 98.72% and 99.34% for Emtricitabine, Rilpivirine and Tenofovir disoproxil fumarate, respectively. Percentage relative standard deviation (<2%) was found for both precision and robustness study showing that the proposed method was precise, specificity, robust and stable in accordance with ICH guidelines.

A simple and cost effective spectrophotometric method is described for the determination of fluvastatin sodium in pure form and in pharmaceutical formulations. When the drug reacts with sodium hydroxide shows absorption maximum at 304 nm and obeys beer's law in the concentration range 5-25 µg mL -1 . The absorbance was found to increase linearly with increasing concentration of FVS, which is corroborated by the calculated correlation coefficient value of 0.9999 (n=5). The apparent molar absorptivity and sandell sensitivity were 1.1905 X 10 4 and 0.0368844 µg cm -2 cm respectively. The slope and intercept of the equation of the regression line are 0.027112 and 0.003539 respectively. The limit of detection and limit of quantification was found to be 0.0811 µg mL -1 & 0.2460 µg mL -1 . The validity of the described procedure was assessed. Statistical analysis of the result has been carried out revealing high accuracy and good precision. The proposed method was successfully applied to the determination of FVS in pharmaceutical formulations without any interference from common excipients. The relative standard deviations were ≤ 0.937%, with recoveries of 98.60% -101.70%.

A simple, accurate, precise, economical and validated uv spectrometric absorption correction method was developed for olmesartan, medoxomil amlodipine besylate and hydrochlorothiazide in bulk and its dosage form. The stock solutions were prepared in methanol followed by further dilutions with double distilled water. The λmax for olmesartan, amlodipine besylate and hydrochlorothiazide were 256.5 nm, 362 nm and 316 nm, respectively. Beer’s law was obeyed in the concentration range of 3-18 μg/mL, 1- 6μg/mL and 2-12 μg/mL, respectively. The method was validated by following the analytical performance parameters suggested by the ICH Guidelines. The percentage assay in commercial formulation was found to be in the range olmesartan 100.06%, amlodipine 99.17% and hydrochlorothiazide 100.14% by the proposed method. The method was validated with respect to linearity, precision and accuracy. recovery was found to be in the range of olmesartan 99.65%,amlodipine 99.97% and hydrochlorothiazide 99.81% by absorbance corrected method. The high recovery and low coefficients of variation conforms the suitability of the method for simultaneous analysis of three drugs in combined tablets.

A simple high performance thin layer chromatographic method for simultaneous quantification of aceclofenac, paracetamol and thiocolchicoside in bulk and tablet dosage form was investigated. Chromatographic separation of the drugs were performed on aluminium plates precoated with silica gel 60 F 254 as the stationary phase and the solvent system consisted of chloroform: methanol: ethyl acetate: glacial acetic acid (5: 2.5: 2.5: 0.1, v/v/v/v). Densitometric evaluation of the separated zones was performed at 272 nm and the method was validated. The R f values and drug content of aceclofenac, paracetamol and thiocolchicoside were 0.52±0.03, 0.72±0.03 and 0.30 ± 0.03 and 100.37%, 100.30% and 100.43% respectively. The calibration curves of peak area versus concentration, which were linear from 50 -300 ng/band of aceclofenac, 250 -1500 ng/ band of paracetamol and 50 -300 ng/band of thiocolchicoside, coefficient of determination (r 2 ) was greater than 0.999. The method was validated for linearity, accuracy, precision, robustness, specificity and application for assay as per ICH guidelines.

A simple, precise and accurate difference spectroscopic method has been developed for the estimation of balsalazide in bulk and in pharmaceutical dosage form. The proposed method is based on the principle that balsalazide can exhibit two different chemical forms in basic and acidic medium that differ in the absorption spectra in basic and acidic medium. Since the drug was freely soluble in distilled water, a stock solution (1 mg/mL) was prepared with distilled water. Further dilution was made by using 0.1 M sodium hydroxide and 0.1 M hydrochloric acid separately. The maxima and minima in the difference spectra of balsalazide were at 460 nm and 354 nm, respectively. Difference in absorbance between these maxima and minima was calculated to find out the amplitude. This amplitude was plotted against concentration. Beer's law is valid in the concentration range of 2-20 µg/mL. The results of analysis have been validated statistically and by recovery studies.