Δ9-Tetrahydrocannabinol (THC), the active substance in marijuana, is known to reduce psychomotor function and cognition thus greatly impairing driving ability. Existing THC detection technologies (urine or blood-based) are not adequate for assessing recent exposure to determine if a driver is operating under the influence. Giner describes a novel approach which involves the utilization of inexpensive disposable electrodes and electrochemical measurements to detect the presence and abundance of target THC molecules in saliva. Saliva testing via electrochemical detection will eliminate the need for expensive and time-consuming analytical techniques which have a turnaround time of several days.