A Chemist's Paradise

Rohith Krishna

I'm here to talk about all things Chemistry, toxicology and forensic science. Make sure to put on some personal protective equipments because the reaction's about to begin.

Episodes

  1. Evaluating the Bleeding Effect in DESI-MSI Molecular Fingerprinting

    Apr 24

    Evaluating the Bleeding Effect in DESI-MSI Molecular Fingerprinting

    My third PhD paper Since its inception in 2004, Desorption Electrospray Ionization Mass Spectrometry (DESI MS) has seen a significant increase in its application to the pharmaceutical and clinical setting, supported by a steady improvement of the sensitivity, mass accuracy, mass resolution, spatial resolution and usability, as well as by the advantages offered by its ambient nature. However, in comparison to the rapid growth for tissue imaging, the uptake of DESI-MSI in fingerprint imaging has not grown a substantial body of knowledge, compared to MALDI-MSI. In this work, we set off to dissect the application of DESI-MSI to fingerprint imaging to explore both the advantages and the potential challenges that might have slowed the uptake, taking stock from our previous work and that of others in this area. During this endeavor we have highlighted advantages but also discovered that, under a range of optimized operating conditions, fingerprint imaging by DESI-MSI is affected by a delocalization phenomenon which we termed “the bleeding effect”. This phenomenon has been shown to be specific to fingerprints, as sample type, as opposed to biological tissues, and may be one of the contributing factors to a seemingly slower uptake of this technique in molecular fingerprinting. Therefore, a description of the observed effect, how to minimize it, and its implications in operational work are discussed. https://doi.org/10.1021/acs.analchem.5c08143

    20 min
  2. Multimodal MSI for Drug Analysis on Fingerprints

    06/14/2025

    Multimodal MSI for Drug Analysis on Fingerprints

    My Second PhD Paper Although drug facilitated sexual assault (DFSA) is an old issue, current statistics on the frequency of this crime have led to growing concerns. As these drugs are metabolised very quickly, toxicological evidence from biological fluids, corroborating the victim's statement, is challenging to recover, especially with late reports. We are proposing an additional method involving the analysis of the victim's fingermarks recovered at the scene(s) of the crime, which may contain the parent drug and its metabolite. As a case study, a multi-modal mass spectrometry-based approach has been developed and explored to detect and image both risperidone and its pharmacologically active metabolite, paliperidone, after contamination of a fingertip at very low concentrations and deposition of a fingerprint on a surface. In particular Matrix Assisted Laser Desorption Ionisation Mass Spectrometry Imaging (MALDI MSI), Desorption Electrospray Ionisation Mass Spectrometry Imaging (DESI MSI) and Soft Ionisation by Chemical Reaction In Transfer, (SICRIT®) have been used in different combinations to both detect the drugs and reconstruct the fingerprint ridge pattern; this approach enables the simultaneous provision of both chemical information (circumstances surrounding the crime) and biometric information. A forensic operational scenario has also been simulated whereby the contaminated fingerprint is deposited on paper and enhanced with a routine fingerprint enhancement technique prior to analysis via mass spectrometry imaging. Overall, our investigation indicates that this additional approach is feasible and is worth exploring further.Check the paper out: https://doi.org/10.1039/D5AN00328H

    19 min

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I'm here to talk about all things Chemistry, toxicology and forensic science. Make sure to put on some personal protective equipments because the reaction's about to begin.