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

Window of detection of cocaine-related alkaloids in oral fluid collected with the FloqSwab™ after coca tea consumption

Coca tea is a popular drink in some countries of South America, where it is presented as a safe energy preparation, based on a limited total content of cocaine of ∼3-5 mg. Tea bags can be bought with no legal considerations in these countries both by locals and tourists, but its consumption can have consequences when consumed overseas. Driving under the influence of cocaine is banned in most of the places in the world and can be documented by oral fluid testing. A study was implemented with coca tea bags (Coca & Muna) purchased in Peru, after a French attorney-at-law contacted the laboratory to assess the involvement of coca tea in the positive oral fluid results of a driver. Ten healthy volunteers consumed 250 mL of coca tea containing 4.5 mg of cocaine. No volunteer reported any change in behavioral effects after consumption of the coca tea. Oral fluid was collected with a swab (FloqSwab™, Copan) over 8 h to follow the elimination of cocaine and its major metabolites (benzoylecgonine and ecgonine methylester). This is the procedure used by the French police. All samples were analyzed by UHPLC-MS-MS after Quantisal™ buffer desorption. As the device does not allow measurement of the amount of collected fluid, the results are qualitative. This is in accordance with the French law that requires a yes or no response about the presence of cocaine, with a minimum required performance level of 10 ng/mL of cocaine or benzoylecgonine. Parent cocaine was identified for 30-120 min. Benzoylecgonine and ecgonine methylester were identified between 1 and 8 h, with a large inter-individual variation. Although it is generally accepted that a 4-5 mg cocaine dose has no significant pharmacological effect, the consumption of coca tea can lead to the suspension of a person's driving license due to a positive oral fluid test.

Evaluation of an Oral Fluid Collection Device and a Solid-Phase Extraction Method for the Determination of Coca Leaf Alkaloids by Gas Chromatography-Mass Spectrometry

Some South American countries have ancient traditions that may pose legal problems, such as the consumption of coca leaves, as this can provide positive results for cocaine use after the analysis of biological samples. For this reason, it is necessary to find specific markers that help differentiate legal from illegal consumption, such as tropacocaine, cinnamoylcocaine, and especially hygrine and cuscohygrine. In this work, two techniques for collecting biological samples are compared: the Quantisal® Oral Fluid collection device and passive drooling. Once the samples were collected, they were subjected to solid-phase extraction for subsequent injection into GC-MS. Different validation parameters included in international guides have been studied to evaluate whether the proposed method is valid for the defined purpose, placing special emphasis on the study of the matrix effect and little value on GC-MS analyses. With respect to this parameter, an increase in the signal was found for CUS and t-CIN, but it was not significant for the rest of the substances studied. The recoveries have varied significantly depending on the way of working, being higher when working with standardized areas. After carrying out work with the oral fluid samples collected from laboratory volunteers, the method was applied to two real samples. The results obtained support the need for further research to overcome certain limitations presented by the device.

Detection of coca alkaloids in oral fluid from coca leaf (tea) consumers: using solid phase extraction to improve validation parameters and widen the detection window

Hygrine and cuscohygrine, two coca leaf alkaloids, have been previously proposed as markers to differentiate legal and illegal cocaine consumption. This is a very common problem in some countries of South America, where the consumption of coca leaves has a long tradition. Analytical methods focusing on the assessment of coca leaf alkaloids, such as cuscohygrine, hygrine, tropacocaine and t-cinnamoylcocaine, in oral fluid are virtually non-existent in forensic toxicology laboratories worldwide due to their lack of application. However, the problem of differentiating legal and illegal cocaine use in criminal justice, DUID (drug-impaired driving) and WDT (workplace drug testing) programs is growing. Therefore, researchers are obliged to develop methods to measure coca leaf alkaloids (cuscohygrine, hygrine and t-cinnamoylcocaine) in biological matrices for further validation for routine analyses in forensic toxicology laboratories. This work aims to optimize a previously published separation method by protein precipitation in oral fluid by using solid-phase extraction (SPE) coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) operating in multiple reaction monitoring (MRM) mode. The use of SPE allowed the matrix effect and the background to be reduced in the chromatograms due to the obtained cleaner extracts. Consequently, improved detection and quantification limits were reached. Findings showed that the detection windows for coca leaf alkaloids were longer than three hours in real oral fluid samples from volunteers who drank a cup of coca tea. These detection windows are quite higher than those previously obtained when using the method based on separation by protein precipitation.

Dereplication of tropane alkaloids from four Erythroxylum species using liquid chromatography coupled with ESI-MSn and HRESIMS

RATIONALE

Tropane alkaloids represent an important class of secondary metabolites, but many of these compounds are already described in the scientific literature, so the use of guided identification and isolation strategies, such as dereplication, represent a fast and safe alternative.

METHODS

For the annotation of the tropane alkaloids the chloroform phases of the four Erythroxylum species were analyzed by high-performance liquid chromatography coupled to mass spectrometry with positive-mode electrospray ionization, then the ions of their protonated molecules, molecular formulas and fragmentation patterns were observed and a comparison of the obtained data with those present in the scientific literature was performed. The compounds not fully annotated were isolated and characterized by 1 H and 13 C nuclear magnetic resonance spectroscopy.

RESULTS

The annotation of 29 tropane alkaloids was performed, some being described for the first time in the family Erythroxylaceae. The chemical profiles of these secondary metabolites in the four Erythroxylum species analyzed were traced and compared. Isolation of three compounds whose mass spectral data were not sufficient for their full annotation was performed. They were 6-(benzoyloxy)-3-(3,5-dimethoxy-4-hydroxybenzoyloxy)tropane, 6-(benzoyloxy)-3-(3,4,5-trimethoxybenzoyloxy)tropane and 6-(benzoyloxy)-3-(3,4,5-trimethoxycinamoyloxy)tropane, first reported in the species Erythroxylum revolutum Mart.

CONCLUSIONS

This work contributes to the phytochemical knowledge of the genus Erythroxylum, and demonstrates the efficiency and importance of using guided isolation methodologies of secondary metabolites in natural products research. Since safe results were presented in the annotation of the compounds evidenced, employing small quantities of organic solvents, when compared to classical methodologies, besides promoting an optimization in the research time.

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

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.