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Mason Malloy


Postgraduate Research Student

Academic and research departments

Department of Chemistry.

My research project

My qualifications

2018
Master of Chemistry Chemistry with Forensic Investigation
University of Surrey

Affiliations and memberships

AMRSC
Associate Member of the Royal Society of Chemistry

My publications

Publications

Mason Courtney Malloy, I. Bogdanović Radović, Z Siketic, M JAKSIC (2018)Determination of deposition order of blue ballpoint pen lines by MeV Secondary Ion Mass Spectrometry, In: Forensic Chemistry7pp. 75-80 Elsevier

Secondary Ion Mass Spectrometry using MeV ion excitation was utilised for the analysis of optically indistinguishable intersecting ballpoint pen lines on paper. It was demonstrated that the technique was able to identify different colorants (dyes and synthetic organic pigments) with high efficiency and in a single measurement. The analysis of ink-ink intersections was performed using the Time-of-Flight mass spectrometer for MeV Secondary Ion Mass Spectrometry. This technique is attached to the heavy ion microprobe at the accelerator facility, and employs focused 8 MeV Si4+ ions for the surface analysis. Molecular imaging allowed for successful identification of sequence deposition order of otherwise optically indistinguishable intersecting lines.

Matea Krmpotić, Dubravka Jembrih-Simbürger, Z Siketic, NM Markovic, Marta Anghelone, Tonči Tadić, Dora Plavčić, Mason Courtney Malloy, Iva Bogdanović Radović (2020)Identification of Synthetic Organic Pigments (SOPs) Used in Modern Artist’s Paints with Secondary Ion Mass Spectrometry with MeV Ions, In: Analytical Chemistry92(13)pp. 9287-9294 American Chemical Society

This work reports on the first systematic study using secondary ion mass spectrometry with MeV ions (MeV-SIMS) for analysis of synthetic organic pigments (SOPs) that can be usually found in modern and contemporary art paints. In order to prove the applicability of the method to different chemical classes of SOPs, 17 pigments were selected for the analyses. The focus was on blue and green phthalocyanines, yellow and red (naphthol AS) azo pigments, red quinacridone, anthraquinone, and diketopyrrolo-pyrrole pigments. Since there are no reference spectra available for this technique, pure pigment powders were measured first to create a database. Simple two-component paint systems were also prepared for testing purposes by mixing synthetic organic pigments with alkyd and acrylic binders. Commercial paints that contain the SOPs with identical C.I. numbers as in the prepared two-component samples were analyzed. All pigments were successfully identified in commercial products in the MeV-SIMS mass spectra through molecular and larger specific fragment ion peaks in the positive-ion mode. The main advantages of MeV-SIMS over other techniques used in SOPs identification, like pyrolysis gas chromatography mass spectrometry (Py-GC/MS), direct-temperature resolved mass spectrometry (DTMS), and laser desorption ionization mass spectrometry (LDIMS), can be summarized as follows: (i) pigments and binders can be detected simultaneously in the same mass spectrum acquired over a short measurement time (up to 500 s), (ii) only small sample flakes are required for the measurements, which are analyzed without any chemical treatment prior to the analyses, (iii) samples are not consumed during the analyses and can be reused for other measurements, e.g., multielemental analysis by other ion beam analysis (IBA) techniques, such as particle-induced X-ray emission (PIXE). Compared to, e.g., Raman spectroscopy, the significant benefit of MeV-SIMS is the exact identification of the SOPs in the paints even if pigments of similar structures are measured.