New evidences on efficacy of boronic acid-based derivatization method to identify sugars in plant material by gas chromatography-mass spectrometry

Quantification of carbohydrates in human serum using gas chromatography–mass spectrometry with the stable isotope-labeled internal standard method

Comparison of two derivatization approaches (silylation and acylation) for carbohydrate separation based on optimizing reaction conditions by artificial neural networks.

Optimization of a new multi-reagent procedure for quantitative mussel digestion in microplastic analysis

Over the last few years, different digestion protocols have been proposed to extract microplastics from mussels, an important product from aquaculture and a relevant economic resource, always scrutinized as a potential pollutant concentrator. In this study, a full factorial experimental design technique has been employed to achieve efficiency in removing biological materials while maximizing the recoveries of five common microplastics (polyethylene, polystyrene, polyethylene terephthalate, polypropylene and polyamide). A robust setpoint was calculated, 2.5% potassium hydroxide at 60 °C for 3 h with 5% hydrogen peroxide and 2.7% of methanol, permitting the quantitative digestion of mussel tissues and recovery of microplastics. These experimental conditions were successfully used to digest whole mussels bought from a local market, which possess high levels of microplastic contamination (41 items/g dry weight). The results highlight the importance of optimizing protocols to develop robust, easy to use and cheap quantitative approaches for analysing microplastic accumulation in edible organisms.

On-tissue boronic acid derivatization for the analysis of vicinal diol metabolites in maize with MALDI-MS imaging

Derivatization reactions are commonly used in mass spectrometry to improve analyte signals, specifically by enhancing the ionization efficiency of those compounds. Vicinal diols are one group of biologically important compounds that have been commonly derivatized using boronic acid. In this study, a boronic acid with a tertiary amine was adapted for the derivatization of vicinal diol metabolites in B73 maize tissue cross-sections for mass spectrometry imaging analysis. Using this method, dozens of vicinal diol metabolites were derivatized, effectively improving the signal of those metabolites. Many of these metabolites were tentatively assigned using high-resolution accurate mass measurements. In addition, reaction interference and cross-reactivity with various other functional groups were systematically studied to verify data interpretation.

Derivatization of Levoglucosan for Compound-Specific δ 13C Analysis by Gas Chromatography/Combustion/Isotope Ratio Mass Spectrometry

Levoglucosan is a thermal decomposition product of cellulose in particulate matter. δ ¹³C value of levoglucosan could be used in studying the combustion mechanisms and chemical pathways. In order to introduce a minimum number of carbon atoms, based on the stereostructure of levoglucosan, a two-step derivatization method with methylboronic acid and MSTFA was developed and carefully optimized. The recommended reaction temperature is 70°C; the reaction time is 60 min for MBA and 120 min for MSTFA derivatization; and the molar ratio of levoglucosan : MBA : MSTFA is 1 : 1: 100 and 1 : 1: 120 and the reagent volume ratio of MSTFA : pyridine is between 1 : 3 and 1 : 4. The developed method achieved excellent reproducibility and high accuracy. The differences in the carbon isotopic compositions of the target boronate trimethysilylated derivative between the measured and calculated ranged from 0.09 to 0.36‰. The standard deviation of measured δ ¹³C value of levoglucosan was between 0.22 and 0.48‰. The method was applied to particle samples collected from the combustion of cellulose at four different temperatures. δ ¹³C values of levoglucosan in particle samples generated from a self-made combustion setup suggesting that combustion temperature play a little role on isotope fractionation of levoglucosan, although ¹³C enriched in levoglucosan during the combustion process.

Characterization of two Pantoea strains isolated from extra-virgin olive oil

The olive oil is an unfavorable substrate for microbial survival and growth. Only few microorganisms use olive oil fatty acids as carbon and energy sources, and survive in the presence of olive oil anti-microbial components. In this study, we have evaluated the occurrence of microorganisms in 1-year-stored extra-virgin olive oil samples. We detected the presence of bacterial and yeast species with a recurrence of the bacterium Stenotrophomonas rhizophila and yeast Sporobolomyces roseus. We then assayed the ability of all isolates to grow in a mineral medium supplemented with a commercial extra-virgin olive oil as a sole carbon and energy source, and analyzed the utilization of olive oil fatty acids during their growth. We finally focused on two bacterial isolates belonging to the species Pantoea septica. Both these isolates produce carotenoids, and one of them synthesizes bioemulsifiers enabling the bacteria to better survive/growth in this unfavorable substrate. Analyses point to a mixture of glycolipids with glucose, galactose and xylose as carbohydrate moieties whereas the lipid domain was constituted by C6-C10 β-hydroxy carboxylic acids.

An Enhanced GC/MS Procedure for the Identification of Proteins in Paint Microsamples

The chemical characterization of materials used in works of art is extremely useful for gaining a better knowledge of the artistic heritage and to guarantee its preservation. A derivatization GC/MS procedure for the identification of proteins in a microsample from painted works of art has been optimized. The amino acid fraction is derivatized using anhydrous dimethylformamide (DMF) as solvent instead of pyridine (Py), commonly used to facilitate the reaction. Although pyridine is often considered a silylation catalyst, there are many instances in which silylation reactions actually are slower in pyridine than other solvents. In addition, pyridine also may have other undesirable effects such as the promotion of secondary products and other chromatographic anomalies. Using DMF, the formation of artifacts is limited and the derivatization yield of hydrophilic amino acids such as proline and hydroxyproline has improved, thus making the identification of organic paint media more straightforward. The method has been validated and successfully applied to identify the binder of the sample taken from the pictorial cycle of the 12th century monastery of Santa Maria delle Cerrate (Lecce, Italy), thus highlighting the use of eggs as a binding medium.

Fructose recognition using new “Off–On” fluorescent chemical probes based on boronate-tagged 1,8-naphthalimide

A fluorescent probe with a planar structure was designed based on a PET mechanism to detect fructose with lower LOD than analytical methods.

Plant gum identification in historic artworks

We describe an integrated and straightforward new analytical protocol that identifies plant gums from various sample sources including cultural heritage. Our approach is based on the identification of saccharidic fingerprints using mass spectrometry following controlled enzymatic hydrolysis. We developed an enzyme cocktail suitable for plant gums of unknown composition. Distinctive MS profiles of gums such as arabic, cherry and locust-bean gums were successfully identified. A wide range of oligosaccharidic combinations of pentose, hexose, deoxyhexose and hexuronic acid were accurately identified in gum arabic whereas cherry and locust bean gums showed respectively Pent_xHex_y and Hex_n profiles. Optimized for low sample quantities, the analytical protocol was successfully applied to contemporary and historic samples including ‘Colour Box Charles Roberson & Co’ dating 1870s and drawings from the American painter Arthur Dove (1880–1946). This is the first time that a gum is accurately identified in a cultural heritage sample using structural information. Furthermore, this methodology is applicable to other domains (food, cosmetic, pharmaceutical, biomedical).

Molecular labels for analysis of amines and diols by spray based ionization-mass spectrometry

A family of imidazolium and pyridinium salts was synthesized for the purpose of labeling amines and 1,2-diols for highly sensitivite analysis by mass spectrometry. The chosen mass labels are shown to serve as effective reporters when bound to particles functionalized with amines or 1,2-diols and the binding is reversible. The straightforward synthetic route allows analogous internal standards to be generated quickly. Solvents amenable to electrospray ionization facilitate the rapid liberation of imidazolium and pyridinium mass labels from particles by hydrolysis in aqueous acid, while the acetal bond remains stable in anhydrous or buffered aqueous solution. Detection of the labels is demonstrated at 1 nM and quantitation of mass labels released from particles is also demonstrated.