Sildenafil detection in coffee powder using Bromocresol green (BCG) as indicator by visible and ultra-violet spectroscopy

Sildenafil Citrate (SC) an active ingredient in Viagra and has become one of the most commonly prescribed pharmaceuticals drugs to cure sexual deficiency. Sildenafil is prohibited but still being sold ‘over the counter’ it prescribed SC is readily available in the ‘black market’ in the formed either doped or as pills to help potency. Most chromatographic study by researches have proven to be a powerful method to detect SC. On the other hand, spectroscopic method that will quantify quantitatively the amount of the SC in its formulation is yet to be explored. In Malaysia it has been reported that SC had been doped to coffee powder to enhance sexual activity to drinkers. In this study, five samples from different manufacturers of coffee powder which claims that their coffee have an extra power that can sexually arouse drinkers were collected from Johor Bahru, Malaysia. These coffee powders were then analyzed for SC using colored method Ultra Violet (UV) Spectroscopy at 424 nm. In this reaction, BCG is used and an intense yellow coloration is formed. This is then, used as an indicator to estimate the amount of sildenafil present. This study illustrated a good result with calibration curve linear up to 0.9983. The percentage of accuracy, error and coefficient variance recorded for sildenafil are 0.12%, 0.2% and 3.01% respectively. From the UV analysis, Sample 5 was identified to be positive and contain 18.81±0.55 μg/ml of SC. The other samples either show the absent of SC contain analogue of SC or maybe the level of detectible of SC in coffee powder was too low.