Development and Validation of Point-of-Care Deployable Sensors for the Rapid Detection of Emerging New Psychoactive Substances (NPS): N-ethylpentylone and MDPHP

Ali, Inayah (2020) Development and Validation of Point-of-Care Deployable Sensors for the Rapid Detection of Emerging New Psychoactive Substances (NPS): N-ethylpentylone and MDPHP. Masters by Research thesis (MSc), Manchester Metropolitan University for the degree of Master of Science (by Research).

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Abstract

The continuous synthesis of new psychoactive substances on the drug market highlights the requirement for a portable, rapid analytical tool with the ability to detect and quantify substances at low concentrations, whilst providing sensitive and reproducible results. Synthetic cathinone’s are the second largest group of new psychoactive substances and are increasingly popular among drug abusers due to their stimulant effects and availability. In this study, the electrochemical detection of two synthetic cathinone’s, 3',4'- methylenedioxy-α-pyrrolidinohexiophenone (MDPHP) and N-ethylpentylone (NEP) were studied using screen-printed graphene electrodes. In regards to cyclic voltammetry, the linear ranges were found to be 25 – 600 µg mL-1 in acetate buffer (0.1 M, pH 5.5) for NEP and 100 – 1000 µg mL-1 in acetate buffer (0.1 M, pH 5.5) for MDPHP. Whilst using cyclic voltammetry in regards to the NEP, the linear ranges were found to be 25 – 600 µg mL-1 in acetate buffer (0.1 M, pH 5.5) using the control NEP and 25 – 500 µg mL-1 in acetate buffer (0.1 M, pH 5.5) using the street sample of NEP. The linear range for MDPHP was found to be 100 – 1000 µg mL-1 in acetate buffer (0.1 M, pH 5.5) and in spiked diluted human urine, for both the control and street sample. The corresponding limit of detection were calculated to be 0.046 µg mL-1 , 0.104 µg mL-1 , 0.195 µg mL-1 , 0.130 µg mL-1 and 0.205 µg mL-1 for the NEP control and street sample in acetate (0.1 M, pH 5.5) , and the MDPHP control and street sample in acetate (0.1 M, pH 5.5) and spiked diluted human urine, respectively. To increase sensitivity of the method, differential pulse voltammetry was utilized and the linear ranges were found to be 25 – 100 µg mL-1 for NEP and 100 – 1000 µg mL-1 for MDPHP. The corresponding limit of detection were calculated to be 0.130 µg mL1 for NEP and 0.348 µg mL-1 for MDPHP. Quantification of MDPHP street samples were also recorded and the possible interference of common adulterants was tested using cyclic voltammetry. The electrochemical techniques studied show that the detection and quantification of synthetic cathinone’s are viable and serves potential to develop as a portable analytical detector.