Stability of Cocaine, Opiates, and Metabolites in Dried Saliva Spots

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.

Saliva Sampling in Therapeutic Drug Monitoring and Physiologically Based Pharmacokinetic Modeling: Review

“…The method for obtaining a dried biological fluid is known as dried matrix spots (DMSs) sampling. It involves spotting the liquid specimen onto a collection card, allowing it to dry, and then transferring it to a tube with an extracting solvent [15,21]. Likewise, Dried saliva spots (DSSs) are reported in the literature as an alternative to liquid oral fluid for TDM [22].…”

“…The efficiency of saliva sample preparation and analysis is improved by combining the DSS method with a highly sensitive detection instrument [22,24]. The assay protocols used for drug testing have been performed by applying a range of analytical techniques, including highperformance liquid chromatography (HPLC) techniques, solidphase extraction (SPE), liquidliquid extraction (LLE), and protein precipitation (PP) approaches [21]. Gas chromatography coupled to mass spectrometry (GCMS) and ultrahigh performance liquid chromatography (UHPLC) coupled to MS/MS, liquid chromatography (LC) coupled to tandem mass spectrometry (MS/MS) have also been commonly used [19].…”

Evaluation of Antipsychotic Drugs’ Stability in Oral Fluid Samples

“…In the present work, DOE was applied to evaluate the response to different storage conditions, and to optimize the long-term stability of compounds in DSS cards. Preservative concentrations were chosen according to the literature [25]. For each of the preservatives, more specific norms were followed.…”

Advances on Bioanalysis: Recent Approaches in the Determination of Biomarkers, Drugs of Abuse and Medicines

“…Finally, a study on the stability of cocaine and opiates in oral fluid samples was presented by Almeida et al [ 11 ]. The authors studied a number of parameters that could influence the stability of the target compounds, namely storage temperature, light, use of preservatives (and respective concentrations), and time.…”