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Here, we present a new application of desorption electrospray ionization (DESI) and laser ablation electrospray ionization (LAESI) mass spectrometry imaging to assess the spatial location of organic compounds, both polar and nonpolar, directly from rock surfaces. Three carbonaceous rocks collected from an aquatic environment and a berea sandstone subjected to a small-scale oil recovery experiment were analyzed by DESI and LAESI. No rock pretreatment was required before DESI and LAESI analyses. DESI detected and spatially mapped several fatty acids and a disaccharide on the surfaces of carbonaceous rocks, and various nitrogenated and oxygenated compounds on the surfaces of berea sandstone. In contrast, LAESI using a 3.4 μm infrared laser beam was able to detect and map hydrocarbons on the surfaces of all rock samples. Both techniques can be combined to analyze polar and nonpolar compounds. DESI can be used first to detect polar compounds, as it does not destroy the rock surface, and LAESI can then be used to analyze nonpolar analytes, as it destroys a layer of the sample surface. Both techniques have the potential to be used in several scientific areas involving rocks and minerals, such as in the analysis of industry-derived contaminants in aquatic sediments or in small-scale rock-fluid interaction experiments.

This work describes the use of laser ablation electrospray ionization mass spectrometry imaging (LAESI imaging) to investigate the diffusion of the mycotoxin patulin from rotten to healthy areas of fruits. Slices of mold-infected and uninfected (control) apples and strawberries were prepared, and this was the only sample preparation step used. An infrared laser beam (2.94 μm) was used to irradiate the slices, resulting in the ablation of sample compounds directly ionized by electrospray and analyzed by mass spectrometry. Multivariate curve resolution - alternating least squares was applied in unfolded LAESI images to obtain relative quantity information. Patulin was not detected in the control samples but was seen in all mold-infected fruits. LAESI images showed the diffusion of patulin from the rotten area to unaffected parts of the fruits. This study points out the advantage of LAESI imaging over traditional analytical methods used to study the diffusion of mycotoxins in fruits., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Fibromyalgia is a rheumatological disorder that causes chronic pain and other symptomatic conditions such as depression and anxiety. Despite its relevance, the disease still presents a complex diagnosis where the doctor needs to have a correct clinical interpretation of the symptoms. In this context, it is valid to study tools that assist in the screening of this disease, using chemical work techniques such as mass spectroscopy. In this study, an analytical method is proposed to detect individuals with fibromyalgia (n = 20, 10 control samples and 10 samples with fibromyalgia) from blood plasma samples analyzed by mass spectrometry with paper spray ionization and subsequent multivariate classification of the spectral data (unsupervised and supervised), in addition to the treatment of selected variables with possible associations with metabolomics. Exploratory analysis with principal component analysis (PCA) and supervised analysis with successive projections algorithm with linear discriminant analysis (SPA-LDA) showed satisfactory results with 100% accuracy for sample prediction in both groups. This demonstrates that this combination of techniques can be used as a simple, reliable and fast tool in the development of clinical diagnosis of Fibromyalgia., (© 2021. The Author(s).)

A method named imprint paper spray ionization mass spectrometry (imprint-PSI-MS) has been developed and employed for the determination of pungency of peppers. A pepper fruit was cut into a triangular shape, deposited onto a triangular paper, and compressed by a homemade press tool aiming to imprint and transfer the pepper constituents onto the paper surface. Subsequently, the triangular paper was submitted to conventional PSI-MS analysis. Twelve peppers were analyzed, ranging from highly pungent to lowly pungent taste. Pepper pungency values from the Scoville scale (in Scoville heat units, SHU) were compared with the ion intensities of the capsaicin and dihydrocapsaicin compounds obtained from the imprint-PSI-MS analysis, and a correlation coefficient of 0.97 was achieved. In addition, the ion intensities of a sugar compound were monitored in all peppers, and the results were compared with the Scoville scale. Low sugar ion intensities were detected in pungent peppers, while high ion intensities were achieved in low-pungent peppers, suggesting that the pepper pungency may be determined by inversely relating pungency to sugar contents. This work demonstrates the utility of the imprint-PSI-MS method to perform rapid qualitative analyses of peppers and estimate the pungency by monitoring the pepper metabolites. Graphical abstract.

Changes in volatile constituents and phenolic compounds were investigated during fruit development of three pitanga biotypes. Constituents were submitted to multivariate analysis and fruit samples were differentiated by selina-1,3,7(11)-trien-8-one (38.2 ± 2.9%) and its epoxide (26.4 ± 7.2%) for the red-orange biotype; by curzerene (15.04 ± 2.1%) and atractylone (8.47 ± 2.1%) for the red biotype; and by spathulenol (3.7 ± 0.8%) and germacrone (54.7 ± 3.1%) for the purple biotype. Hydrolysable tannins such as mono-O-galloyl-d-glucose, 1,2,6-tri-O-galloyl-β-d-glucose, tellimagrandin II, and eugeniflorin D 2 were identified, as well as oenothein B as the major compound (32.43 ± 7.1 mg/g dry fruit). During pitanga's maturation, anthocyanin content increased, while flavonoid and tannin contents decreased. Higher contents of the majority of phenolic compounds occurred in the red-orange biotype. Biosynthesis of phenolic compounds was influenced by biotype and degree of maturation, whereas chemovariation in essential oil constituents was mainly due to biotypes, thus confirming essential oil chemotypes of E. uniflora., (Copyright © 2018 Elsevier Ltd. All rights reserved.)