Determination of guaiphenesin in anti-tussive pharmaceutical preparations containing dextromethorphan by first- and second-derivative ultraviolet spectrophotometry

Fabrication of graphene nanosheet–multiwalled carbon nanotube–polyaniline modified carbon paste electrode for the simultaneous electrochemical determination of terbutaline sulphate and guaifenesin

A sensitive electrochemical method is developed for the simultaneous determination of terbutaline sulphate (TBS) and guaifenesin (GF) at a carbon paste electrode modified with graphene nanosheet–multiwalled carbon nanotube–polyaniline composite (GNS–MWCNT–PANI).

Voltammetric assay of Guaifenesin in pharmaceutical formulation

The electrochemical oxidation of Guaifenesin in a pharmaceutical formulation containing Guaifenesin has been carried out in Britton-Robinson buffer (BRB) (0.04 mol L-1) on platinum electrode. Guaifenesin exhibits a well-defined irreversible oxidation peak at 0.924 V/ref. The influence of pH on the oxidation of Guaifenesin was studied in BRB (pH range 2-5). A method for the analysis of Guaifenesin in BRB (0.04 mol L-1, pH 2), which allows quantification over the range 20-60 microg mL-1, was proposed and successfully applied to the determination of Guaifenesin in syrup with mean recovery and relative standard deviation of 103.3% and 1.32%, respectively.

Simultaneous Determination of Cyproterone Acetate and Ethinylestradiol in Tablets by Derivative Spectrophotometry

Derivative spectrophotometry offers a useful approach for the analysis of drugs in multi-component mixtures. In this study a third-derivative spectrophotometric method was used for simultaneous determination of cyproterone acetate and ethinylestradiol using the zero-crossing technique. The measurements were carried out at wavelengths of 316 and 226 nm for cyproterone acetate and ethinylestradiol respectively. The method was found to be linear (r2>0.999) in the range of 0.5-6 mg/100 ml for cyproterone acetate in the presence of 35 microg/100 ml ethinylestsradiol at 316 nm. The same linear correlation (r2>0.999) was obtained in the range of 10-80 microg/100 ml of ethinylestradiol in the presence of 2 mg/100 ml of cyproterone acetate at 226 nm. The limit of determination was 0.5 mg/100 ml and 10 microg/100 ml for cyproterone acetate and ethinylestradiol respectively. The method was successfully applied for simultaneous determination of cyproterone acetate and ethinylestradiol in pharmaceutical preparations without any interferences from excipients.

Determination of guaifenesin in human serum by capillary gas chromatography and electron capture detection

A method for the quantitation of guaifenesin in human serum has been developed and validated. The procedure involves liquid-liquid extraction of the serum sample in the presence of mephenesin as an internal standard, followed by derivatization and analysis using capillary gas chromatography (GC) and electron capture detection (ECD). Different solvents were tested for extraction of guaifenesin from serum. n-Hexane/dichloromethane (1:1, v/v) gave the highest recovery and the lowest background and was chosen as the extraction solvent. After extraction, the residue of guaifenesin was derivatized at 60 degrees C for 30 min, with trifluoroacetic acid anhydride (TFAA) in toluene in the presence of pyridine. Excess trifluoroacetic acid anhydride was removed using dilute solution of ammonium hydroxide. The method proved to be linear over the range of 25.0-1000 ng/ml. Recovery of guaifenesin from spiked samples was consistent, averaging 75.5% at 50.0 ng/ml with a range of 72.0-80.0% (N = 8 determinations) and averaging 78% at 800 ng/ml with a range of 76.0-81.0% (N = 8 determinations). The internal standard recovery was also consistent averaging 72.8% with a range of 67.0-76.0% (N = 16 determinations).

Simultaneous estimation of phenylpropanolamine HCl, guaiphenesin and diphenylpyraline HCl in syrups by LC

A simple, precise and accurate HPLC method was developed for the simultaneous estimation of phenyl-propanolamine HCl, guaiphenesin and diphenylpyraline HCl in syrup. The method was carried out on a Shimpak C8 column with a mobile phase consisting of acetonitrile-triethylamine (pH adjusted to 3.5 using orthophosphoric acid; 0.5%), (35:65, v/v) at a flow rate of 1.2 ml min(-1). Detection was carried out at 210 nm. Diphenhydramine was used as internal standard. The validation of the method was also carried out.

Simultaneous determination of dextromethorphan HBr and bromhexine HCl in tablets by first-derivative spectrophotometry

A rapid, simple and direct assay procedure based on first-derivative spectrophotometry, using a zero-crossing and peak-to-base measurement at 234 and 324 nm, respectively, has been developed for the specific determination of dextromethorphan HBr and bromhexine HCl in tablets. Calibration graphs were linear with the correlation coefficients of 0.9999 for both analytes. The limit of detections were 0.033 and 0.103 microgram ml-1 for dextromethorphan HBr and bromhexine HCl, respectively. A HPLC method has been developed as the reference method. The results obtained by the first-derivative spectrophotometry were in good agreement with those found by the HPLC method.