Portable and low-cost colorimetric office paper-based device for phenacetin detection in seized cocaine samples

An office paper-based colorimetric device is proposed as a portable, rapid, and low-cost sensor for forensic applications aiming to detect phenacetin used as adulterant in illicit seized materials such as cocaine. The proposed method uses white office paper as the substrate and wax printing technology to fabricate the detection zones. Based on the optimum conditions, a linear analytical curve was obtained for phenacetin concentrations ranging from 0 to 64.52µgmL^‒1, and the straight line was in accordance with the following equation: (Magenta percentage color) = 1.19 + 0.458 (C_Phe/µgmL^‒1), R² = 0.990. The limit of detection was calculated as 3.5µgmL^‒1 (3σ/slope). The accuracy of the proposed method was evaluated using real seized cocaine samples and the spike-recovery procedure.