Detection of cocaine and cathinones by electrochemical fingerprinting using nanomaterials

Illicit drugs use and abuse remains an increasing challenge for worldwide authorities and, therefore, it is important to have accurate methods to detect them in seized samples, biological fluids and wastewaters. They are recently classified as the latest group of emerging pollutants as their consumption increased tremendously in recent years.

Nanomaterials have gained much attention over the last decade in the development of sensors for a myriad of applications. The applicability of these nanomaterials, functionalized or not, significantly increases and are therefore highly suitable for use in the detection of drugs of abuse.

We have assessed the suitability of various nanoplatforms for the electrochemical detection of illicit drugs, such as graphene, singled-walled carbon nanotubes, multi-walled carbon nanotubes functionalized with platinum nanoparticles, gold nanoparticles and platinum nanoparticles. Graphene and singled-walled carbon nanotubes were drop-casted onto graphite screen printed electrodes and left to dry at room temperature. Multi-walled carbon nanotubes were functionalized with platinum nanoparticles using a simple and efficient chemical process, in which carboxylic acid-functionalized multi-walled carbon nanotubes were mixed with chloroplatinic acid in a mixture of ethylene glycol and water to result in platinum-functionalized multi-walled carbon nanotubes. The functionalized multiwalled carbon nanotubes were drop-casted onto graphite screen printed electrodes. Gold and platinum nanoparticles were deposited by electrodeposition from a solution of chloroauric acid and chloroplatinic acid, respectively, by cyclic voltammetry.

The electrochemical fingerprints of cocaine and cathinones (such as mephedrone, alpha-polyvinylpirolidone, methylmethcatinone, chloroethcatinone, chloromethcathinone, etylone) were elucidated on the above-mentioned nanoplatforms. Square wave voltammetry was performed as a high-performance electrochemical method. This allowed for the sensitive and selective (class selectivity) of the investigated illicit drugs.