Commercially Available Blue Diode Laser Engraver Operating at 455 nm as an Affordable LD-REIMS Ionization Source

Lasers are commonly used for mass spectrometric applications to perform laser ablation-desorption and ionization; however, the use of visible light is not very common. Here, we report a commercially available visible light laser engraver operating at 455 nm as an ionization source, generating rich spectral profiles featuring predominantly lipid species, such as fatty acids and glycerophospholipids. Laser settings such as the speed of movement over the sample and laser power were tested, resulting in an optimum laser speed of 300 mm/min and a laser power of 30-50% for the analysis of fresh salmon tissue samples. Spectra generated were found to be similar to those produced by a conventional REIMS mechanism using Joule heating of the tissues, which was consolidated by comparative studies of the ion formation mechanism. The generated spectra show a slightly higher signal in the lower mass range, suggesting a higher degree of in-source fragmentation; however, no spectral feature was unique to either method. To test the suitability of the visible laser system to act as an REIMS-like profiling technique for food authenticity testing, we assessed the discrimination of Norwegian farmed salmon samples (n = 26) produced using conventional and organic farming methods.

Recent Advances in Combinations of TLC With MALDI and Other Desorption/Ionization Mass-Spectrometry Techniques

The combination of planar chromatography with desorption/ionization mass-spectrometry (MS) techniques provides chemists with unique tools for fast and simple separation of mixtures followed by the detection of analytes by the most powerful analytical method. Since its introduction in the early 1990s, thin-layer chromatography (TLC)/matrix-assisted mass spectrometry (MALDI) has been used for the analysis of a wide range of analytes, including natural and synthetic organic compounds. Nowadays, new desorption/ionization approaches have been developed and applied in conjunction with planar chromatography competing with MALDI. This review covers recent developments in the combination of TLC with various desorption/ionization MS methods which were made in recent several years.

CeO2-CB nanocomposite as a novel SALDI substrate for enhancing the detection sensitivity of pharmaceutical drug molecules in beverage samples

SALDI-MS analysis of pharmaceutical drug molecules (amitriptyline, imipramine and promazine) using carbon-based substrates, namely, activated charcoal (AC), carbon nanotubes (CNTs), carbon black (CB), graphene (rGO), graphene oxide (GO) and graphite, was explored and compared with the conventional organic matrix of MALDI. CB exhibited superior performance with respect to the other substrates in terms of detection sensitivity. Despite the effectiveness of CB to detect all drug molecules, it demonstrated a number of background signals, which may be an issue for the analysis of other molecules in the future. Therefore, for the first time, a CeO₂-CB nanocomposite was synthesized and applied as a novel SALDI substrate to minimize the background signals and stabilize CB when exposed to high laser power. The nanocomposite was characterized using XRD, TEM, FTIR, UV-Vis and N₂ sorpometry. The spectrum obtained using the novel nanocomposite in the absence of the drug molecules showed minimal background signals compared to CB. Additionally, the CeO₂-CB nanocomposite enhanced the detection sensitivity of the drug molecules with a limit of detection (LOD) of 100 ng/mL. This active substrate nanocomposite was further applied for the analysis of drug-spiked beverages without sample pretreatment or extraction, mimicking cases encountered by forensic toxicologists. All of the drugs and/or their adducts were detected in the drug-spiked beverage samples.