Abstract
Drug abuse still represents a global problem, and it is associated with an increased risk of diseases, injuries, and deaths. Cocaine (COC) and opiates are the most abused drugs and account for a significant number of fatalities. Therefore, it is important to develop methods capable of effectively identifying and quantifying these substances. The present study aims to evaluate the long-term stability of COC, ecgonine methylester (EME), benzoylecgonine (BEG), cocaethylene (COET), norcocaine (NCOC), morphine (MOR), codeine (COD) and 6-monoacetylmorphine (6-MAM) in oral fluid samples. The analytes of interest were isolated from the matrix (50 µL) using the dried saliva spots (DSS) sampling approach and were subsequently analyzed by gas chromatography coupled with tandem mass spectrometry (GC–MS/MS). The parameters that could influence the stability of the target compounds were studied, and these were storage temperature, light, use of preservatives (and respective concentrations), and time. The effects of each parameter were evaluated using the design of experiments (DOE) approach. The stability of the target analytes was improved when the DSS were stored at room temperature, in the presence of light and using 1% sodium fluoride. The best conditions were then adopted for the DSS storage and long-term stability was assessed. COD was only stable for 1 day, EME was stable for 3 days, COC, COET, NCOC and 6-MAM were stable for 7 days, MOR for 14 days and BEG remained stable throughout the study (136 days). This is the first study that evaluates the stability of these compounds in oral fluid samples after application in DSS cards, and optimizes the conditions in order to improve their stability.
Highlights
Cocaine is the major alkaloid of Erythroxylum coca [1]and its first use dates back more than 4500 years ago, when coca leaves were used for religious and ritual ceremonies by the Andean civilizations [2]
Data analysis was performed in MINITAB®, version 17, and the response was given by the relative peak area
The present work allowed for the establishment of the best conditions to improve the stability of COC, opiates, and metabolites in oral fluid samples, when applied in Dried Saliva Spots (DSS)
Summary
Cocaine (benzoylmethylecgonine; COC) is the major alkaloid of Erythroxylum coca [1]and its first use dates back more than 4500 years ago, when coca leaves were used for religious and ritual ceremonies by the Andean civilizations [2]. COC is one of the most widely used stimulants and illicit drugs in Europe [2], and since its popularity has increased in recent years it is no longer considered an “elite drug” [3]. Its consumption is associated with numerous health problems such as neurological impairment, cardiovascular disorders, as well as social problems and death [5,6,7]. Opiates, both licit and illicit, are another class of drugs commonly consumed worldwide and their use has been increasing in recent years [6]. Opiates use can cause problems in the cardiovascular, nervous, respiratory, and gastrointestinal systems [8,9]
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