Disposable screen printed sensor for the electrochemical detection of methamphetamine in undiluted saliva

Background

Methamphetamine has an adverse effect on the ability to drive safely. Police need to quickly screen potentially impaired drivers therefore a rapid disposable test for methamphetamine is highly desirable. This is the first proof-of-concept report of a disposable electrochemical test for methamphetamine in undiluted saliva.

Results

A screen printed carbon electrode is used for the N,N′-(1,4-phenylene)-dibenzenesulfonamide mediated detection of methamphetamine in saliva buffer and saliva. The oxidized mediator reacts with methamphetamine to give an electrochemically active adduct which can undergo electrochemical reduction. Galvanostatic oxidation in combination with a double square wave reduction technique resulted in detection of methamphetamine in undiluted saliva with a response time of 55 s and lower detection limit of 400 ng/mL.

Conclusions

Using a double square wave voltammetry technique, rapid detection of methamphetamine in undiluted saliva can be achieved, however there is significant donor variation in response and the detection limit is significantly higher than desired. Further optimization of the assay and sensor format is required to improve the detection limit and reduce donor effects.

Electronic supplementary material

The online version of this article (doi:10.1186/s13065-016-0147-2) contains supplementary material, which is available to authorized users.

Disposable screen printed sensor for the electrochemical detection of delta-9-tetrahydrocannabinol in undiluted saliva

Background

Cannabis has an adverse effect on the ability to drive safely, therefore a rapid disposable test for Δ⁹-tetrahydrocannabinol (Δ⁹-THC), the psychoactive component of cannabis, is highly desirable for roadside testing.

Results

A screen printed carbon electrode is used for the N-(4-amino-3-methoxyphenyl)-methanesulfonamide mediated detection of Δ⁹-THC in saliva. Mediator placed in an overlayer was galvanostatically oxidized and reacted with Δ⁹-THC to give an electrochemically active adduct which could be detected by chronoamperometric reduction. Detection of 25-50 ng/mL Δ⁹-THC spiked into undiluted saliva was achieved with a response time of 30 s. A trial of the sensors with four cannabis smokers showed sensitivity of 28 %, specificity of 99 % and accuracy of 52 %.

Conclusions

Rapid electrochemical detection of Δ⁹-THC in undiluted saliva has been demonstrated using a disposable sensor, however the sensitivity is lower than acceptable. Further optimization of the assay and sensor format is required to improve the sensitivity of response to Δ⁹-THC.