Chromatographic methods for simultaneous determination of diiodohydroxyquinoline and metronidazole in their binary mixture.

Two chromatographic methods were developed for analysis ofdiiodohydroxyquinoline (DIHQ) and metronidazole (MTN). In the first method, diiodohydroxyquinoline and metronidazole were separated on TLC silica gel 60F254 plate using chloroform: acetone: glacial acetic acid (7.5: 2.5: 0.1, by volume) as mobile phase. The obtained bands were then scanned at 254 nm. The second method is a RP-HPLC method in which diiodohydroxyquinoline and metronidazole were separated on a reversed-phase C18 column using water : methanol (60 :40, V/V, PH=3.6 )as mobile phase at a flow rate of 0.7 mL.min-1 and UV detection at 220 nm. The mentioned methods were successfully used for determination of diiodohydroxyquinoline and metronidazole in pure form and in their pharmaceutical formulation.

Report: Simultaneous determination of naphazoline hydrochloride, chlorpheniramine maleate and methylene blue in their ternary mixture.

Validated spectrophotometric and chemometric methods were developed for determination of Naphazoline Hydrochloride (NAP), Chlorpheniramine maleate (CLO) and Methylene blue (MB) in their ternary mixture. Method A was a spectrophotometric method, where NAP and MB were determined using second derivative (D²) spectrophoto metric method using the peak amplitudes at 299 nm and 337 nm for NAP and MB respectively , while CLO was determined using second derivative ratio (DD²) spectrophotometric method using the peak amplitude at 276.6 nm. Method B used the chemometric techniques; principal component regression (PCR) and partial least squares (PLS) for determination of NAP, CLO and MB using the information contained in the absorption spectra of their ternary mixture solutions. The proposed methods have been successfully applied for the analysis of NAP, CLO and MB in their pharmaceutical formulation and the obtained results were statistically compared with the reported methods.

Spectrophotometric and spectrofluorimetric methods for determination of Racecadotril.

Two accurate and sensitive spectrophotometric and spectrofluorimetric methods were developed for determination of Racecadotril. In the first method reduction of Fe3+ into Fe2+ in presence of o-phenanthroline by Racecadotril to form a stable orange-red ferroin chelate [Fe-(Phen)3]2+ was the basis for its determination. The absorbance at 510 nm was measured and linear correlation was obtained in the concentration range of 2.5-25 µg mL(-1). In the second method the native fluorescence of Racecadotril in acetonitrile solvent at λ=319 nm when excitation was at 252 nm is used for its determination. Linear correlation was obtained in the concentration range of 50 to 500 ng mL(-1). The proposed methods were applied for determination of Racecadotril in bulk powder with mean accuracy of 100.39±1.239 for the spectrophotometric method and 100.09±1.042 for the spectrofluorimetric method. The proposed methods were successfully applied for determination of Racecadotril in its pharmaceutical dosage form.

Simultaneous determination of methocarbamol and ibuprofen or diclofenac potassium using mean centering of the ratio spectra method.

Accurate and sensitive methods were developed for simultaneous determination of methocarbamol and ibuprofen or diclofenac potassium in their binary mixtures, and in the presence of a methocarbamol related substance (guaifenesin) using mean centering of the ratio spectra method. The results obtained were statistically compared with the reported HPLC methods; no significant difference between the proposed methods and the reported methods was found regarding either accuracy or precision.