Spectrophotometric determination of sildenafil citrate in pharmaceutic formulations
Viagra � has quickly turn out to be one of the most popular plus traditionally used drugs throughout the remedying of erection dysfunction. 3 In parallel with the particular growth in its consumption, there were the increase in typically the number of cases of adulteration and even falsification of this particular medication. 4 To be able to date, it comes with a lack of a monograph and description of your official method with regard to its analysis within the Brazilian pharmacopoeia and in the primary international works with this category. In look at of these considerations, it is best to guarantee typically the quality of these products sold for typically the protection of customers' health.
The methods described in typically the literature for sildenafil citrate analysis contain voltammetry, 5. six high performance chemical chromatography with UV 7-9 detection or coupled to mass spectrometry, 10 micellar electrokinetic chromatography, 10 gas chromatography, 10 capillary electrophoresis, 13 spectroscopy of elemental magnetic resonance 16 and spectrophotometry. 15-17 Chromatographic methods will be the most used inside the determination of sildenafil citrate in several matrices (pharmaceutical formulations, plasma plus urine), 7-9, 11as well as in the particular determination of pharmacokinetic parameters. 성인용품 have low detection limits, which usually justifies their employ in the examination of biological fluids. However, they need a very long time in the initial sample prep steps, use higher amounts of solvents and the instrumentation is more expensive, which raises the final cost of typically the analyzes. For the particular analysis of pharmaceutical formulations, it is desirable that methods using affordable approaches and that give fast, precise in addition to accurate results will be available.
Molecular consumption spectrophotometry is the instrumental manner of alternative widely used for this specific purpose, having the advantages of being very simple, involving the using low-cost equipment in addition to being able to be easily automated. The methods defined within the literature with regard to the determination regarding sildenafil citrate simply by spectrophotometry 15-17 are usually scarce found many disadvantages, because they need heating for coloring development in acetonitrile medium 16 or even involve laborious procedures with many stages of sample coping with, including extractions using chloroform. 15
This kind of work describes the development of a fast and even simple spectrophotometric approach based on the particular reaction between sildenafil citrate and p-chloranil 16 accelerated by the addition associated with hydrogen peroxide, immediately producing a secure violet complex (? max = 535 nm) at place temperature.
EXPERIMENTAL ELEMENT
Materials and gear
The volume sizes were created with category A burettes or even Eppendorf micropipette (100-1000 � L). The particular glassware used inside the preparation regarding the solutions was grade A and the weighings were performed on an analytical balance AG204, Mettler Toledo. Absorbance proportions were created using a Varian spectrophotometer type Cary 100 equipped with glass or even quartz cuvettes having an optical path of 1 cm.
Reagents plus solutions
All reactants and solvents used in this work were of analytical quality. Working solution your five. 68 x twelve -3 mol M -1 of sildenafil citrate (supplied simply by Pfizer, 95%) has been prepared in methanol (Mallinckrodt, Xalostoc, Mexico). This solution will be stable for fifteen days if stashed in the freezer. 5 p-chloranil (Sigma, St. Louis, USA), working solution 1 ) 00 x twelve -2 mol M -1 of p-chloranil (Sigma, St. Louis, USA) was ready in dioxane (Mallinckrodt, Xalostoc, Mexico). Hydrogen peroxide solution a few. 00 mol L -1was prepared by the right dilution of the Peridrol answer (Merck, Darmstadt, Philippines, 30% w or w) with methanol, previously standardized in accordance to the permanganimetric procedure. 18
therefore that its final concentration went from 8. 52 x 12 -5 to 1. 70 x 10 -3 mol L -1. The volume from the flasks was finished with methanol up in order to the mark and then the absorbance dimensions were made at 535 nm in opposition to a similarly well prepared blank, but with out the addition involving sildenafil citrate. Typically the calibration curve has been constructed by conspiring the absorbance values?? measured as a functionality of the sildenafil citrate concentration.
Test preparation and evaluation
Samples of medications containing sildenafil citrate out there were purchased through local pharmacies and analyzed by the proposed method, within just their expiration date ranges.
Sixteen tablets, by the same order, were weighed by using an analytical balance plus the mean mass price was determined. Therefore, they were sprayed on agate grain until an excellent powder was obtained. A portion involving sprayed sample equal to 20 mg of sildenafil citrate has been exactly weighed and even subjected to mixing with 5 milliliters of methanol in a magnetic stirrer for 15 minutes. This solution was initially transferred to a ten mL volumetric flask and the volume constructed with methanol till the meniscus. Well then, the perfect solution is was filtered about Whatman 41 quantitative filter paper along with a 750 �L differential was taken in addition to analyzed according to the recommended process for the structure from the analytical competition.