A major challenge within forensic science is the development of accurate and robust methodologies that can be utilized on-site for detection at crime scenes and can be used for analyzing multiple sample types. The recent expansion of electrochemical sensors to tackle this hurdle requires sensors that can undergo analysis without any pretreatment. Given the vast array of samples that are submitted for forensic analysis, this can pose a major challenge for all electrochemical sensors, including electrochemiluminescent (ECL)-based sensors. Within this contribution, we demonstrate the capacity for an ECL-based sensor to address this challenge and it is potential to detect and quantify atropine from a wide range of samples directly from herbal material to spiked solutions. This portable platform demonstrates satisfactory analytical parameters with linearity across a concentration range of 0.75 to 100 μM, reproducibility of 3.0%, repeatability of 9.2%, and a detection limit of ∼0.75 μM. The sensor displays good selectivity toward alkaloid species and, in particular, the hallucinogenic tropane alkaloid functionality within complex matrices. This portable sensor provides rapid detection alongside low cost and operational simplicity, thus, providing a basis for the exploitation of ECL-based sensors within the forensic arena.

Electrochemiluminescence (ECL) has increased in popularity as a result of its inherent advantages, including but not limited to portability, simplicity of use, and low reagent consumption. However, its significant advantages are often over shadowed as a result of its limited specificity. ECL emissions are intrinsically broad and lack the definition of other available analytical techniques. Furthermore, species with similar functional groups have almost identical electrochemical behavior and thus typically emit within approximately the same potential region. Within this contribution we have demonstrate the use of pH controlled ECL to prove the presence of two individual species within a mixed sample. Analysis at a single pH would not provide this information. We have illustrated the potential of this methodology to quantify scopolamine alongside sister tropane alkaloid atropine, a known ECL interferent. Previously the two alkaloids could not be distinguished from one another using a single technique which did not involve a separation strategy. pH controlled ECL is a simple approach to improve the specificity of a basic [Ru­(bpy)3]2+ film based sensor. By exploiting molecular characteristics, such as pK a, we have been able to fine-tune our methodology to facilitate identification of analytes previously exhibiting indistinguishable ECL emission. Thus, by improving specificity, while maintaining operational simplicity and inexpensive design, we have been able to highlight the potential power of ECL for identification of structurally similar compounds. Further improvements of specificity, such as demonstrated within this contribution, will only further future applications of ECL sensors across a range of different fields.

Electrochemiluminescent sensors for point-of-care devices; a screening strategy for the direct detection of hallucinogens within a variety of biological matrices.

While debates have raged over the relationship between trance and rock art, unambiguous evidence of the consumption of hallucinogens has not been reported from any rock art site in the world. A painting possibly representing the flowers of Datura on the ceiling of a Californian rock art site called Pinwheel Cave was discovered alongside fibrous quids in the same ceiling. Even though Native Californians are historically documented to have used Datura to enter trance states, little evidence exists to associate it with rock art. A multianalytical approach to the rock art, the quids, and the archaeological context of this site was undertaken. Liquid chromatography−mass spectrometry (LC-MS) results found hallucinogenic alkaloids scopolamine and atropine in the quids, while scanning electron microscope analysis confirms most to be Datura wrightii. Three-dimensional (3D) analyses of the quids indicate the quids were likely masticated and thus consumed in the cave under the paintings. Archaeological evidence and chronological dating shows the site was well utilized as a temporary residence for a range of activities from Late Prehistory through Colonial Periods. This indicates that Datura was ingested in the cave and that the rock painting represents the plant itself, serving to codify communal rituals involving this powerful entheogen. These results confirm the use of hallucinogens at a rock art site while calling into question previous assumptions concerning trance and rock art imagery.

The expansion of electrochemical sensors to biomedical applications at point of care requires these sensors to undergo analysis without any pre-treatment of extraction. This poses a major challenge for all electrochemical sensors including electrochemiluminescent (ECL) based sensors. ECL offers many advantages for biomedical applications however; obtaining results from complex matrices has proven to be a large hurdle for the application of ECL sensors within this field. This work demonstrates the potential of cathodic ECL to detect and quantify homocysteine with 0.1 nM limit of detection, which is associated with hyperhomocysteinemia, in blood. This near infrared quantum dot (NIR QD) based ECL sensor displays good linearity allowing for rapid detection and providing a basis for exploitation of ECL based sensors for biomedical diagnostics utilising homocysteine as a model cathodic co-reactant. This work will lay the foundations for future developments in biosensing and imaging fields and stands as an initial proof of concept for the utilization of cathodic ECL technologies for biomedical applications once the limits of detection within clinically relevant levels has been achieved. This work illustrates the potential of cathodic ECL sensors, using Hcy as a model complex, for the detection of biomolecules. EXPERIMENTAL Materials Qdot® 800 ITK™ organic quantum dots, (1 μM in decane) were obtained from Invitrogen. Lumidot™ 560 and 640 nm QDs, (5 mg/mL in toluene), chitosan (medium molecular weight, 75-85 % de-acetylated), and all other chemicals were purchased from Sigma-Aldrich. All solutions were prepared in milli-Q water (18 mΩ cm). Bovine whole blood samples utilised within this study were obtained from Wishaw Abattoir Ltd following University of Strathclyde ethical approval. These were stored in aliquots at-20 ºC. Aliquots were defrosted at room temperature on the day of analysis and used immediately. Instrumentation A CH instrument model 760D electrochemical analyser using a standard 3 electrode setup including a 3 mm diameter GC working electrode, Pt wire counter electrode and Ag/AgCl 3 M KCl reference electrode purchased from IJ Cambria Scientific Ltd (UK) was utilised to record all electrochemical measurements. GC electrodes were cleaned following the pro-ASSOCIATED CONTENT Supporting Information Supporting material includes ECL responses for the interactions with reactive oxygen species (Figure S1), ECL responses for 1 mM K2S2O8 in blood with the Stern-Volmer and modified Stern-Volmer plots for this data (Figure S2). The ECL dependence for the interferents given in Figure 6 (Figure S3). Chromatographic experimental details are also included (Figure S4). This material is available free of charge via the Internet at http://pubs.acs.org.

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The abuse of methamphetamine (MA) is to date detected and subsequently verified through the monitoring of MA and its metabolites within biological specimens. Current approaches require complex sample purification strategies...

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