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A new highly sensitive high-performance liquid chromatographic method with fluorescence detection (HPLC-FLD) in zero-order emission mode was developed for the first time for the simultaneous determination of piroxicam (PRX) and norfloxacin (NRF) in biological fluids. The fluorescence detector wavelengths were set at 278 nm for excitation and zero-order mode for emission. The zero-order emission mode produced greater sensitivity for the measurement of both drugs than a fixed emission wavelength (446 nm). The new developed method was validated according to International Conference of Harmonization (ICH) guidelines. Linearity was found to be over concentration ranges 0.001-20 μg/ml and 0.00003-0.035 μg/ml for PRX and NRF, respectively. The limits of detection were 4.87 × 10 −4 and 1.32 × 10 −5 μg/ml for PRX and NRF, and the limits of quantitation were 1.47 × 10 −3 and 4.01 × 10 −5 μg/ml, respectively. The current fluorescence method was found to be more sensitive than most commonly used analytical methods and was successfully applied for simultaneous determination of PRX and NRF in biological fluids (serum and urine) with recoveries ranging from 91.67% to 100.36% for PRX and from 96.00% to 101.43% for NRF.

Objective: To develop a sensitive, fast and selective method for the determination of sumatriptan succinate (SUM) in pharmaceutical samples. Methods:The method is based on measuring the synchronous fluorescence of SUM using ∆λ of (12 0 nm) and at a wavelength of excitation and emission of 230 and 325 nm respectively, using Agilent Technology, Cary eclipse, G9800AA model Luminescence spectrometer. Effect of variables on fluorescence emission intensities was studied such as solvent, surfactant, and pH. The proposed method was validated in term of linearity, limit of detection as per the international conference on harmonization guidelines ICH Q (R1). Results:The linearity of the method was obtained with a wide range of (50-150) ng/ml with a high value of correlation coefficient value of (0.992). Limits of detection (LOD) and limits of quantitation (LOQ) were found to be 16.3 and 49.5 ng/ml respectively, the mean recovery was found to be 99.1% with low relative standard deviation (% RSD). The method was also compared statistically with the reference method using t-test and f-test, the results show no difference either in pure or pharmaceutical tablets. Conclusion:The obtained results revealed that the developed method can be applied successfully for the determination of SUM in drug formulations samples with good accuracy and precision. I In nt te er rn na at ti io on na al l J Jo ou ur rn na al l o of f A Ap pp pl li ie ed d P Ph ha ar rm ma ac ce eu ut ti ic cs s

Green, sensitive and selective spectrophotometric methods were developed for the determination of nitrite in water samples. The methods (A, B and C) are based on the reduction of 5-nitroimidazoles; metronidazole (MTL), secnidazole (SCL) and tinidazole (TNL), respectively, followed by diazotization using nitrite in acidic medium, then coupling with pyrogallol (PG). The amount of nitrite was determined by measuring the absorbance of the colored product at 385 nm. The new methods were linear in the ranges of 2.5–30 μgml

Purpose: To develop simple and reliable quantitative methods for the determination of cilnidipine (CLD) in pharmaceutical tablets.Methods: Two simple and sensitive methods (spectrophotometric and spectrofluorimetric) were developed for the determination of cilnidipine (CLD) in pure form and in a pharmaceutical preparation. Spectrophotometric method (A) is based on oxidation of CLD with a known excess amount of Nbromosuccinamide (NBS) in acidic medium, followed by addition of methyl orange indicator and absorbance measurement at 510 nm. The spectrofluorimetric method (B) is based on oxidation of CLD to cerium (IV), followed by measurement of fluorescence emission of Ce (III) at 350 nm. Factors that affect the performance of the two methods were studied and optimized.Results: The spectrophotometric and spectrofluorimetric procedures were successfully used for measuring CLD levels in pharmaceutical dosage form, in the ranges of 2.0 - 25.0 and 0.25 - 11.2 μg/mL, at detection limits of 1.05 and 0.13 μg/mL, respectively. There were no significant differences between the proposed methods and a standard reference method (p < 0.05).Conclusion: The developed methods provide simple and reliable procedures for quantitative measurement of CLD in bulk and tablet forms. Keywords: Cilnidipine, Oxidation, Spectrophotometric, Spectrofluorimetric, Drug formulation