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The need for agile and proper identification of drugs of abuse has encouraged the scientific community to improve and todevelop new methodologies. The drug lysergic acid diethylamide (LSD) is still widely used due to its hallucinogenic effects. The use ofvoltammetric methods to analyze narcotics has increased in recent years, and the possibility of miniaturizing the electrochemical equipmentallows these methods to be applied outside the laboratory; for example, in crime scenes. In addition to portability, the search for affordable andsustainable materials for use in electroanalytical research has grown in recent decades. In this context, employing paper substrate, graphite pen-cil, and silver paint to construct paper-based electrodes is a great alternative. Here, a paper-based device comprising three electrodes was drawnon 300 g/m2watercolor paper with 8B pencils, and its efficiency was compared to the efficiency of a commercially available screen-printedcarbon electrode. Square wave voltammetry was used for LSD analysis in aqueous medium containing 0.05 mol/L LiClO4. The limits of detec-tion and quantification were 0.38 and 1.27 mol/L, respectively. Both electrodes exhibited a similar voltammetric response, which was alsoconfirmed during analysis of a seized LSD sample, with recovery of less than 10%. The seized samples were previously analyzed by GCMStechnique, employing the full scan spectra against the software spectral library. The electrode selectivity was also tested against 3,4-methylene-dioxymethamphetamine (MDMA) and methamphetamine. It was possible to differentiate these compounds from LSD, indicating that the devel-oped paper-based device has potential application in forensic chemistry analyses., Financial support provided by the Polícia Científica do Estado de São Paulo for the partnership, and Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP - Process 2016/23825-3), Fundação para a Ciência e Tecnologia, FCT, Portugal, (UID/QUI/00686/2016 and UID/QUI/00686/2019), and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (Process Capes Pro Forenses 25/2014).

In real-life situations, where samples such as wet soil, body fluids or foodstuff, contain high content of solids/impurities with a limited amount of liquid, sample collection within an adsorptive substrate prior ion determination emerges as a necessary step. For this reason, paper-based technology has been widely studied in development of potentiometric sensors and their application in determination of ions in various samples. Paper is easily available, inexpensive, capable of wicking fluids, disposable and biodegradable, thus provides clear benefits to be integrated with potentiometric ion sensors. In turn, potentiometric ion sensors are characterized by relatively cheap and compact design and, most importantly, by the ability to perform quick and easy ion determination. In this review, all aspects of application of paper substrates in potentiometry will be critically discussed. Those will include the application of paper substrates in paper-based sampling, fabrication of paper-based ion-selective and reference electrodes, and paper-based potentiometric devices. Economic Development Board (EDB) Ministry of National Development (MND) Nanyang Technological University National Environmental Agency (NEA) National Research Foundation (NRF) The authors would like to thank NEWRI (Nanyang Environment and Water Research Institute) and Singapore's Economic Development Board (EDB) for their financial support of this research. Undergraduate Research Experience on Campus Programme (URECA) is acknowledged for provided support. SCARCE is supported by the National Research Foundation, Prime Minister's Office, Singapore, the Ministry of National Development, Singapore, and National Environment Agency, Ministry of Sustainability and the Environment, Singapore under the Closing theWaste Loop R&D Initiative as part of the Urban Solutions & Sustainability e Integration Fund (Award No. USS-IF-2018-4).

The fabrication, characterization, and applications of paper-based screen-printed carbon electrodes (SPCE) are discussed. In particular, microscopy images of the working electrode surface show a reproducible 3D pattern that enhances the performance of the device compared to that of a polyester-based SPCE. Gold nanoparticles and CdSe@ZnS quantum dots are detected using different electrochemical techniques. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.