Detection of sildenafil and sildenafil analogues in coffee powder using liquid chromatography tandem mass spectrometry

Abstract

Sildenafil citrate (SC) is an active ingredient found in Viagra, a prescribed pharmaceutical drug to cure erectile dysfunction (ED). Consuming SC will increase the blood flow to the body which lead to an increase in blood pressure to men with ED for normal sexual life. Sildenafil abuse was reported by media for those who are not diagnosed with ED but taking SC for the sexual affect that it brings. SC legally is forbidden, if consumed without prescription might cause headache, vision disturbances, heart problem and even failure, thus might lead to death. Camouflaged by the pleasure and masking the threat it brings, Sildenafil can be taken on its own or spiked in beverages, candy, herbal supplement and coffee powder. Various steps have been taken by the authorities to curb and hopefully stop this problem. In order to avoid prosecution, black-marketeers have introduced Sildenafil analogues. Thus, the authorities have been forced to introduce new procedures to detect these drugs in consumer products. Hence this study is focused on the detection of Sildenafil and Sildenafil analogues in coffee powder using LC-MSMS. The chemical fragmentation elucidation was done by interpreting the chromatograms obtained. Fifteen samples of confiscated coffee powders were obtained from local market; six were found to contain either Sildenafil alone or mixture of Sildenafil analogues namely Yohimbine; 8.53 ppm (S5), Sildenafil; 0.51 ppm (S7), Homosildenafil; 5.87 ppm (S7), Thiosildenafil; 1.01 ppm (S7) Thiodymethyl sildenafil; 131.77 ppm (S7), ThiohomoSildenafil; 0.0064 ppm (S9), Tadalafil; 21.03 ppm (S11), Norneosildenafil; 0.02 ppm (S11), Carbodenafil; 0.1 ppm (S12), NDesmethylacetildenafil; 4.7 ppm (S12) and Hydroxythiohomosildenafil; 0.02 ppm (S13). The advantage of using LC-MSMS in this study includes its high sensitivity, specificity and the mass characteristic ions of each analyte fulfilling the identification requirements for confirmatory qualitative analysis