Development of a Reliable Method for Assessing Coca Alkaloids in Oral Fluid by HPLC-MS-MS

A reliable method based on high-performance liquid chromatography-tandem mass spectrometry has been developed for the assessment of coca alkaloids/metabolites [cocaine (COC), benzoylecgonine (BE), cocaethylene (CE), ecgonine methyl ester (EME), anhydroecgonine methyl ester (AEME), tropococaine (TRO), transcinnamoylcocaine (trCIN), cuscohygrine (CUS) and hygrine (HYG)] in oral fluid samples from cocaine abusers and from coca leaves consumers (coca leaves chewers and coca tea drinkers). Oral fluid samples were collected by the passive drool technique (spitting), and after centrifugation the supernatant was treated for protein removal by adding acidified acetonitrile. The developed method was fully validated according to the international criteria and good results have been obtained (intraday and inter-day precisions were lower than ±20%, intraday and inter day accuracy was within the 75-116% range, and LODs/LOQs was lower and close to cut-off values for COC and BE). The proposed method has been successfully applied to oral fluid samples from cocaine abusers, and also from coca leave chewers and coca tea drinkers. CUS and HYG were only found in oral fluid from people who chewed coca leaves and drank coca tea and were not detected in cocaine abusers. Both CUS and HYG could be good markers in oral fluid for distinguishing people who consume coca leaves legally (coca leave chewers and coca tea drinkers) from those who consume illegal cocaine.