Modified Ambient Mass Spectrometric Methods For Field Screening And Confirmation Of Forensic Evidence

Abstract

The utility of field-portable analytical instrumentation has the potential to revolutionize many fields of science, particularly for forensic science and law enforcement. While colorimetric testing can be employed for drug evidence screening, the influx of novel psychoactive substances has significantly decreased the effectiveness of this investigation strategy. One approach to meeting the needs of today’s practitioner is coupling flexible, ambient ionization techniques with portable mass spectrometric (MS) instrumentation. Ambient ionization techniques have a rich history of being amendable to the sample at hand. Since their inception in 2005, numerous techniques saturate the field. The main drive for this development is to allow the analysis of wider sample classes with doing as minimal sample preparation required. Herein, the efforts to develop and perform a selection of simplified, rapidly-interchangeable, ambient ionization sources will be discussed, including paper spray ionization (PSI) and paper cone spray ionization (PCSI). First reported by Cha and Kim, PCSI has been shown adept at bulk analyte analysis. Here, a modified PCSI source that allows for real-time extraction and filtration of forensic samples known to hinder screening or compromise hygiene on MS systems is investigated. Also, studies will be included that evaluates an inter-source comparison of ionization methods that have already shown broad utility within the forensic community, PSI and direct analysis in real time (DART), in order to discern analytical performance and usability in forensic evidence processing. While portable MS systems have been shown capable of assisting investigative decision-making, this single technology does not fulfill the two-tiered identification guidelines suggested by the Scientific Working Group for the Analysis of Seized Drugs (SWGDRUG) for generating prosecutorial data. By integrating surface-enhanced Raman spectroscopy (SERS) with a portable MS system, a rapid, yet robust, method for drug evidence identification is discussed, while looking at the development and characterization of this instrumental strategy.