Artificial oral fluid characterisation: Potential for use as a reference matrix in drug testing

Abstract

Quality assurance schemes for drug‐screening programmes require access to large quantities of biological matrices for reference or control samples. This presents problems when the availability of a matrix, such as oral fluid (OF) for screening or for confirmatory purposes, limits the collection of large volumes. In such cases, synthetic alternatives of OF may provide a solution. The preparation of an artificial (synthetic) oral fluid (AOF) was conducted by dissolving its components (salts, surfactant, antimicrobial agent and mucin) in water. We characterised the physical properties of AOF to determine its suitability as a matrix for quality assurance purposes. The evaluation of pH, specific gravity (SG), conductivity (mS cm−1), freezing point depression (°C), light‐scattering and kinematic viscosity (mm2 s−1) showed AOF to be a stable, reliable matrix. Synthetic OF was prepared using components (mucin, surfactants and so on) obtained from different suppliers and a comparison was performed. Our results suggest that AOF is a feasible matrix for the preparation of quality assurance samples for confirmatory or drug screening programmes.

Stability of drugs of abuse in synthetic oral fluid investigated using a simple “dilute and inject” method of analysis

“…A SOF has the distinct advantage of consistency and is easily prepared simply by dissolving its components in water. Our work has shown that it appears to be a stable and reliable matrix for drug testing purposes 18 . We have developed a simple dilute and inject analytical method to detect six different drugs of abuse (morphine, amfetamine, cocaine, diazepam and THC) including the primary metabolite of cocaine, benzoylecgonine spiked in SOF.…”

“…The SOF composition is presented in Table 2 and was prepared as described in our previous paper 18 . SOF was prepared by dissolving the compounds in water taking extra care when handling mucin and Tween® 20 as both have the potential to foam.…”

“…The preparation of the SOF and its subsequent characterisation for quality control purposes has been described previously by our group. 18 The SOF was spiked with six commonly misused drugs and their metabolites: morphine, amfetamine, benzoylecgonine, cocaine, diazepam and THC at 100 ng/ml. composition of the mobile phase and various analytical columns.…”

“…Due to the variability in human OF composition, there is a clear need to be able to synthesise synthetic oral fluid (SOF) that would allow for its use as a reproducible reference material for the preparation of quality control samples for confirmatory or drug‐screening programmes as a substitute for human OF 18 …”

“…[15][16][17] Due to the variability in human OF composition, there is a clear need to be able to synthesise synthetic oral fluid (SOF) that would allow for its use as a reproducible reference material for the preparation of quality control samples for confirmatory or drug-screening programmes as a substitute for human OF. 18 Enders and McIntire reported a "dilute and inject" LC-MS/MS method for the detection of opioids in oral fluid. The oral fluid was collected utilising a sampling device and diluted 1 in 10 prior to LC-MS/MS MRM (multiple reaction monitoring) with a run time of just below 3 min.…”