Rapid screening of high-priority N-nitrosamines in pharmaceutical, forensic, and environmental samples with paper spray ionization and filter cone spray ionization-mass spectrometry

Fourier Transform Ion Trap Mass Analysis by Deciphering Ion Ejection Signals in the Frequency Domain

Mass analysis in an ion trap is conventionally realized through time domain analysis of the ejected ion current collected from an electron multiplier (EM), in which the ion ejection time is found to have a correlation with the mass-to-charge (m/z) ratio of the ion. In this study, we investigated a new method for mass analysis by examining ion ejection signals in the frequency domain. Theoretical analysis and ion trajectory simulations show that ions of the same m/z ratio are ejected from an ion trap at regular intervals, producing a periodic pulsed signal on the EM. The period of this pulsed ejection signal is directly linked to the m/z values of the ions. To realize this method experimentally, a broadband preamplifier was built and integrated on a miniature ion trap mass spectrometer (the "Brick" series from Nier Inc.) to capture this pulsed ion ejection signal collected from the EM. Experimental results were in good agreement with theoretical and simulation analyses. This method has the potential to improve the mass resolution of an ion trap mass analyzer. As a proof-of-concept demonstration, a peak width of 0.1 Da at a m/z value of 281 was achieved in experiments.

Ambient ionisation mass spectrometry for drug and toxin analysis: A review of the recent literature

Ambient ionisation mass spectrometry (AIMS) is a form of mass spectrometry whereby analyte ionisation occurs outside of a vacuum source under ambient conditions. This enables the direct analysis of samples in their native state, with little or no sample preparation and without chromatographic separation. The removal of these steps facilitates a much faster analytical process, enabling the direct analysis of samples within minutes if not seconds. Consequently, AIMS has gained rapid popularity across a diverse range of applications, in particular the analysis of drugs and toxins. Numerous fields rely upon mass spectrometry for the detection and identification of drugs, including clinical diagnostics, forensic chemistry, and food safety. However, all of these fields are hindered by the time-consuming and laboratory-confined nature of traditional techniques. As such, the potential for AIMS to resolve these challenges has resulted in a growing interest in ambient ionisation for drug and toxin analysis. Since the early 2000s, forensic science, diagnostic testing, anti-doping, pharmaceuticals, environmental analysis and food safety have all seen a marked increase in AIMS applications, foreshadowing a new future for drug testing. In this review, some of the most promising AIMS techniques for drug analysis will be discussed, alongside different applications of AIMS published over a 5-year period, to provide a summary of the recent research activity for ambient ionisation for drug and toxin analysis.

Application of a Modified 3D-PCSI-MS Ion Source to On-Site, Trace Evidence Processing via Integrated Vacuum Collection

Trace evidence, including hair, fibers, soil/dust, and gunshot residue (GSR), can be recovered from a crime scene to help identify or associate a suspect with illegal activities via physical, chemical, and biological testing. Vacuum collection is one technique that is employed in recovering such trace evidence but is often done so in a targeted manner, leaving other complementary, chemical-specific information unexamined. Here, we describe a modified 3D-printed cone spray ionization (3D-PCSI) source with integrated vacuum collection for on-site, forensic evidence screening, allowing the processing of targeted physical traces and nontargeted chemical species alike. The reported form factor allows sample collection, onboard extraction, filtration, and spray-based ionization in a singular vessel with minimal handling of evidence by the operator. Utilizing authentic forensic evidence types and portable MS instrumentation, this new method was characterized through systematic studies that replicate CSI applications. Reliability in the form of false positive/negative response rates was determined from a modest, user-blinded data set, and other attributes, such as collection efficacy and detection limit, were examined.