Advances in Sample Preparation Workflows for Oral Fluid Analysis

The analysis of drugs of abuse in oral fluids is a solution that is gaining popularity due to its less invasive collection technique as compared to blood or urine collection. However, there are some issues with the buffer used in the collection devices for oral fluid testing. It is often difficult to remove all of the surfactants from the buffer, which can cause matrix effects. Oftentimes solid phase extraction or lengthy extraction techniques are utilized. Finding a method that uses a simple sample preparation paired with accurate and robust quantitation of the analytes is important for laboratories running these tests. An LC-MS/MS method was developed for the quantitation of these compounds using a Raptor Biphenyl 50 x 2.1 mm, 2.7 µm analytical column equipped with a Raptor Biphenyl EXP 5 x 2 mm, 2.7 µm guard column. Samples were prepared in oral fluid and combined with Quantisal buffer. Samples were tested using three different sample preparation techniques: salt-assisted liquid-liquid extraction (SALLE); supported liquid extraction (SLE); and dilute and shoot. The results of these extraction techniques were investigated and compared using recovery, linearity, matrix effects, and accuracy and precision.