The adulteration of whiskey with analgesics and sedation drugs has been a common practice to prevent hangover the following day and promote loss of consciousness. In both situations, the portable and low cost detection platforms are of paramount importance for forensic investigations. This report describes the use of electrochemical paper‐based analytical devices (ePADs) fabricated by pencil drawing for detecting metamizole, paracetamol and midazolam maleate in whiskey. Different types of paper substrates and graphite pencils were initially characterized with ferrocyanide. The best results were achieved using vegetal paper and Aquarelle/6B pencils. ePADs revealed a decrease in current signal indicating a short lifetime, thus limiting their use to disposable sensors. Despite the short lifetime, the graphite pencil ePADs revealed good electrochemical reproducibility (RSD=3.3 %). The forensic feasibility of the proposed ePADs was demonstrated through the analysis of metamizole and paracetamol in whiskey. The limit of detection (LOD) achieved for paracetamol and metamizole were 45 and 20 mg L−1, respectively. ePADs were also tested to detect midazolam maleate in whiskey. The signal recorded exhibited linear correlation in a wide concentration range (25–1000 mg L−1) and a LOD of ca. 5 mg L−1. Considering the disposability and operational simplicity, ePADs offer a good strategy for detecting adulterations in alcoholic beverages at the point‐of‐need.

This study describes the use of electrochemical paper-based analytical devices (ePADs) drawn with graphite pencil for the determination of ascorbic acid (AA) in commercial tablets. ePADs were fabricated using vegetal paper and graphite pencil. First, the three-electrode electrochemical cell drawn using a graphical software and toner lines were laser printed on the vegetal paper surface to delimit the electrode areas. Then, the electrode regions were manually painted with graphite pencil. Afterwards, the pseudo-reference electrode was defined with the deposition of silver ink over the graphite surface. Cyclic voltammetry and square wave voltammetry (SWV) experiments were performed to optimize the electroanalytical parameters as well as to quantitatively determine the AA concentration in two commercial tables. ePADs exhibited linear behavior for a concentration range between 0.5 and 3.0 mmol L. The achieved limit of detection and sensitivity were 70 μmol L and 0.47 μA/mmol L, respectively. The AA concentration levels found by SWV experiments in both Cenevit and Energil C were 2.80 ± 0.02 and 3.10 ± 0.01 mmol L, respectively. The accuracy of the proposed devices was investigated through recovery experiments in three concentration levels and it presented values between 95 and 115%.

The cover picture illustrates the fabrication process of electrochemical paper‐based analytical devices (ePADs) fabricated by pencil drawing for detecting analgesics and sedation drugs in whiskey. Analgesics are commonly used to adulterate alcoholic beverages to prevent the hangover. On other hand, sedative drugs are occasionally added to alcoholic beverages to promote loss of consciousness, amnesia and hallucination in the victim. The ePADs fabricated with graphite pencil were successfully tested to detect metamizole, paracetamol and midazolam maleate, as model drugs, in whiskey samples. Due to the inherent portability, disposability, low cost, operational simplicity and speed, ePADs can emerge as an attractive strategy for point‐of‐need by crime scene or police agents. More details are discussed in the article by Anderson A. Dias, Thiago M. G. Cardoso, Cyro L. S. Chagas, Virgílio X. G. Oliveira, Rodrigo A. A. Munoz, Charles S. Henry, Mário H. P. Santana, Thiago R. L. C. Paixão and Wendell K. T. Coltro. DOI: 10.1002/elan.201800308