Voltammetric study and determination of the new psychoactive substances 25H-NBOH and 25B-NBOH in synthetic urine and blotter paper samples using a composite electrode

The dramatic escalation in the quantity of new synthetic drugs in recent years has prompted the pursuit of novel methods for identifying and quantifying these substances. Notably among them are the substituted phenethylamines known as NBOHs and NBOMes. Electrochemical study and quantification of new psychoactive substances (NPS) 25H-NBOH and 25B-NBOH in synthetic urine and synthetic blotting papers is presented using differential pulse voltammetry (DPV) on a composite electrode (CE) made of graphite and polycaprolactone (PCL). Based on the cyclic voltammetry (CV) results, we propose that the drug oxidation mechanism comprises two main steps. Initially, it involves the oxidation of the secondary amine, necessitating the removal of one electron from the amino-nitrogen atom, leading to dealkylation. Subsequently, bromine or methoxy substitution takes place. Under the optimized experimental conditions for the differential pulse voltammetry (DPV) studies, analytical curves were obtained in the range of 100 to 800 ng mL−1 for 25H-NBOH and 100 to 700 ng mL−1 for 25B-NBOH (r² = 0.999), with detection limits of 19 ng mL−1 and 23 ng mL−1, respectively, and quantification limits of 64 ng mL−1 and 76 ng mL−1. The proposed method was employed for quantification of the drugs in synthetic urine and synthetic blotting papers, with recovery values between 95% and 106%, demonstrating no interference from the matrices.