A novel, fast, and sensitive stability-indicating HPLC method was developed, fully validated, and applied to the simultaneous determination of aliskiren and hydrochlorothiazide in a combined formulation. Effective chromatographic separation was achieved using a phenyl analytical column with isocratic elution using the mobile phase 0.030 M ammonium acetate-acetonitrile (60 + 40, v/v) at a flow rate of 0.40 mL/min. The UV spectrophotometric detector was set at 280 nm. The method was linear over the concentration ranges of 1.5-4.5 and 0.125-0.375 μg/mL for aliskiren and hydrochlorothiazide, respectively. The intraday and interday RSD values were less than 6.1%, while the relative percentage error, Er, was less than 5% for both analytes. Both drugs were subjected to stress conditions of acidic and alkaline hydrolysis, oxidation, and thermal degradation. The proposed method proved to be stability indicating by resolution of the drugs from their forced degradation products. The method was applied successfully to the QC and content uniformity tests in combined commercial tablets.
Bisphosphonates are used to treat various skeletal disorders, as they modulate bone metabolism by inhibition of the osteoclast-mediated bone resorption. These compounds are both polar and ionic, and therefore, by using reversed phase liquid chromatography are eluted rapidly. Hydrophilic interaction liquid chromatography (HILIC) is an advantageous technique for the separation and analysis of polar molecules. As the elution order in HILIC is reversed to reversed phase liquid chromatography, a reasonable retention and selectivity for polar compounds is expected. In this work the retention mechanism of three bisphosponates, namely risedronate, tiludronate and zoledronate, was investigated under zwitterionic HILIC conditions. The key factors influencing the retention of the analytes on a zwitterionic ZIC®-pHILIC column (150.0 × 2.1 mm i.d., 200 Å, 3.5 μm) have been systematically investigated. It was found that apart from partition, electrostatic repulsions play an important role in the retention of bisphosphonates. Peak tailing of risedronate and zoledronate was improved by the addition of sodium pyrophosphate in the mobile phase. A zwitterionic hydrophilic interaction liquid chromatography-photodiode array (HILIC-PDA) method was further optimized and fully validated to quantitate risedronate in commercial film-coated tablets. The calibration curves for risedronate showed good linearity (r > 0.9991) within the calibration range tested. The intra- and inter-day coefficient of variation (CV) values was less than 0.6%, while the relative percentage error (%Er) was less than −2.3%. Accelerated stability studies of risedronate conducted under several degradation conditions including hydrolysis, oxidation and heat demonstrated the selectivity of the procedure. A short-run analysis of not more than 6 min allowed the analysis of large samples per day. The applicability of the method for the quantitation of risedronate was demonstrated via the analysis of commercial tablets containing this compound.
A simple, rapid, and stability-indicating HPLC method has been developed, fully validated, and applied to the quantification of paracetamol, pseudoephedrine hydrochloride, and chlorpheniramine maleate in a pharmaceutical formulation, using hydrochlorothiazide as an internal standard. Chromatographic separation was achieved isocratically on an RP porous graphitized carbon analytical column (125 2.1 mm id, particle size 5 m) using 5.0 mM ammonium acetateacetonitrile (35 + 65, v/v) mobile phase at a flow rate of 0.50 mL/min. UV spectrophotometric detection at 220 nm was used. The method had linear calibration curves over the range of 3070 g/mL for paracetamol, 1.84.2 g/mL for pseudoephedrine hydrochloride, and 120280 ng/mL for chlorpheniramine maleate. The intraday and interday RSD values were less than 3.2 for all compounds, while the relative error was less than 2.9. Accelerated stability studies performed under various stress conditions proved the selectivity of the method. The developed method was applied successfully to QC and content uniformity tests of commercial tablets.
This article describes the development and validation of a selective high-performance liquid chromatography method that allows, after liquid–liquid extraction and pre-column derivatization reaction with quercetin, the quantification of aluminium chlorohydrate in antiperspirant creams. Chromatographic separation was achieved on an XTerra MS C18 analytical column (150 × 3.0 mm i.d., particle size 5 μm) using a mobile phase of acetonitrile:water (15:85, v/v) containing 0.08 % trifluoroacetic acid at a flow rate of 0.30 mL min−1. Ultraviolet spectrophotometric detection at 415 nm was used. The assay was linear over a concentration range of 3.7–30.6 μg mL−1 for aluminium with a limit of quantitation of 3.74 μg mL−1. Quality control samples (4.4, 17.1 and 30.6 μg mL−1) in five replicates from five different runs of analysis demonstrated intra-assay precision (% coefficient of variation <3.8 %), inter-assay precision (% coefficient of variation <5.4 %) and an overall accuracy (% recovery) between 96 and 101 %. The method was used to quantify aluminium in antiperspirant creams containing 11.0, 13.0 and 16.0 % (w/w) aluminium chlorohydrate, respectively.
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