Editorial: Luminescence and electrochemical methods: Analysis of physical evidence

In this inspiring issue, three interesting and diverse peer-reviewed articles were published: two full research articles and one review article. The topics of these articles covered luminescence and electrochemical methods for the analysis of physical evidence. The three articles discussed the detection of fentanyl and its analogs via in situ electrochemical-surface enhanced Raman spectroscopy (EC-SERS), the utilization of electrochemistry to probe the degradation and time since deposition of blood and, finally, the role of fluorescence spectroscopy in the analysis of blood. These articles highlighted some of the main challenges currently facing forensic practitioners working with different types of physical evidence and provided suggestions for some of the fundamental unanswered questions. Can we rapidly differentiate between fentanyl and its analogs? Can we predict the degradation behavior of bloodstains at different temperatures using electrochemistry? How can fluorescence spectroscopy be beneficial for blood analysis? Due to the increase in casework related to fentanyl and its analogs, there is a genuine need for simple, rapid and sensitive methods for their identification and differentiation. In this respect, the in situ electrochemical-surface enhanced Raman spectroscopy (EC-SERS) method was developed by Ott et al. for the rapid detection of fentanyl and six of its analogs. In this detailed study, the authors initially optimized the experimental conditions for the SERS substrate and amperometric detection. The synthesis and roughening of the SERS substrate (Ag nanoparticles) were performed in situ utilizing cyclic voltammetry (CV) and multipulse amperometric detection (MPD). Consequently, MPD parameters were optimized to obtain the maximum response and improved enhancement due to SERS hot spot generation. Major functional groups in fentanyl were identified, and acetyl fentanyl, methoxyacetyl fentanyl, furanyl fentanyl, acryl fentanyl, valeryl fentanyl and despropionyl fentanyl (4-ANPP) analogs were successfully analyzed due to their difference in the amide portion. This is significant for crime laboratories when minor differences in the drug molecule structure can make identification challenging. Sensitivity was evaluated by determining the limit of detection of each drug by measuring the signal OPEN ACCESS