Mass Spectrometric Techniques Research Articles

Why Consumers Prefer Green Friariello Pepper: Changes in the Protein and Metabolite Profiles Along the Ripening.

Fruit ripening is a physiologically complex process altering texture, color, flavor, nutritional value, and aroma. However, some fruits are consumed at an early stage of ripening due to the very peculiar characteristics varying during ripening. An example is a particular ecotype of pepper, the Friariello pepper, among the most important representatives of Campania (Southern Italy) agro-alimentary culture. In this study, for the first time, the physiological variations during Friariello ripening (green, veraison, and fully ripe) were evaluated by hyphenated mass spectrometric techniques in a proteomic and metabolomic approach. We found that Lutein and Thaumatin are particularly abundant in the green Friariello. Friariello at an early stage of ripening, is rich in volatile compounds like butanol, 1 3 5-cycloheptatriene, dimethylheptane, α-pinene, furan-2-penthyl, ethylhexanol, 3-carene, detected by gas chromatography-mass spectrometry (GC-MS) analysis, which give it the peculiar fresh and pleasant taste. The detected features of Friariello may justify its preferential consumption in the early ripening stage and outline new knowledge aimed at preserving specific agro-cultural heritage.

Profiling of non-polar lipids in tears of contact lens wearers during the day

PurposeThis study explored whether the non-polar lipids in the human tear fluid lipidome show diurnal variation with and without contact lens wear. It also addressed the relationship between changes in ocular comfort during the day with the level of non-polar lipids. MethodsTear samples were collected in the morning and evening with and without contact lenses using fine glass capillary tubes and were analysed by chip-based nano-electrospray ionization tandem mass spectrometric techniques. Tear levels of cholesteryl esters (CE), wax esters (WE) and triacylglycerides (TAG) were quantified. ResultsTAG 48:0, 52:0 and WE 26:0/16:0, and 27:0/17:0 increased from morning to evening. TAG 52:2, WE 21:0/16:0, 21:0/18:1 and 28:0/18:1 decreased during the day when no lenses were worn. CE 21:0 was the only non-polar lipid that increased from morning to evening in contact lens wear. WE 21:0/16:0 and 27:0/17:0 were lower in the morning in contact lens wear compared to no lens wear (p ≤ 0.05). The level of non-polar lipids did not correlate with ocular comfort at the end of the day. ConclusionEven though the level of some of non-polar lipid species changed from morning to evening the total level of major tear non-polar lipids remained unchanged during the day with and without contact lens wear. The effect of change in the quantity and structure of lipid species on tear stability and ocular comfort warrants more investigation.

A combined experimental and computational structural study of the N-(2-cyanophenyl)disulfonamides derived from 5-bromo- and 5-iodoanthranilamide

One-pot sulfonyl chloride-pyridine mediated disulfonylation of the aniline nitrogen atom and dehydration of the primary amide group of the 5-halogenoanthranilamide derivatives afforded the corresponding N-(2-cyanophenyl)disulfonamides, exclusively. This facile reaction makes use of readily available substrates and gives high yield of the products in short reaction time. The structures of these compounds were characterised using a combination of nuclear magnetic resonance (1H NMR & 13C NMR), infrared (IR) and mass spectrometric techniques. Their geometry was distinctly confirmed by single crystal X-ray diffraction (XRD) analysis of N-(4-bromo-2-cyanophenyl)-N-(methylsulfonyl)methanesulfonamide (2a) as representative model. The geometrical optimizations of structures of compounds 2a, 2b and 2c were also investigated by means of density functional theory (DFT) calculations. The optimized structural parameters (bond lengths, bond angles, and torsion angles) of 2a have been compared with those of the X-ray structure.

On the Set of Fellini’s Movies: Investigating and Preserving Multi-Material Stage Costumes Exploiting Spectroscopic and Mass Spectrometric Techniques

Since the second half of the 19th century, the world of textile production was radically changed both in terms of esthetics and of the performances leading to industrial products whose chemical properties were totally unknown and unexplored. Stage costumes are typical examples of multi-material art objects where different natural and synthetic materials were used to fulfil specific purposes. This research was performed in the framework of a diagnostic and restoration campaign of dresses of two Federico Fellini’s movies (“Il Casanova” and “Roma”). For the characterization of the textile fibers, Attenuated Total Reflection Fourier Transform Infrared Spectroscopy (ATR-FTIR) and Pyrolysis Gas Chromatography coupled with Mass Spectrometry (Py-GC/MS) were employed. The structure of the metallic threads was investigated by Scanning Electron Microscopy coupled with Energy-Dispersive X-ray Spectroscopy (SEM-EDX). Dye identification was carried out by High Performance Liquid Chromatography coupled with Diode Array Detector and mass spectrometry (HPLC-DAD, HPLC-ESI-Q-ToF). The analytical approach adopted allowed us to fully characterize the costumes composed of natural, synthetic and artificial fibers dyed with complex mixtures of last generation synthetic dyes. The results collected were fundamental to fine-tune an effective restoration aimed at minimizing the damages due to ageing, inaccurate home-made restoration interventions, or poor conservation conditions.

Reactivity of transition metal dioxide anions MO2− (M = Co, Ni, Cu, Zn) with sulfur dioxide in the gas phase: An experimental and theoretical study

The reactivity of transition metal dioxide anions of cobalt, nickel, copper and zinc with sulfur dioxide has been investigated in the gas phase by mass spectrometric techniques and theoretical calculations. Dioxide anions of the late transition metals Cu and Zn promote an unprecedented fast and efficient oxidation to the sulfate radical anion through a double oxygen transfer, whereas the earlier transition metals Ni and Co only undergo the addition of two SO2 molecules. The ligation of a water molecule to ZnO2− switches the reaction path to a single oxygen anion transfer, forming SO3−.

NanoUPLC-MSE reveals differential abundance of gluten proteins in wheat flours of different technological qualities

Gluten proteins contribute to the rheological properties of dough. Mass spectrometric techniques help to understand the contribution of these proteins to the quality of the end product. This work aimed to apply modern proteomic techniques to characterize and provide a better understanding of gluten proteins in wheat flours of different technological qualities. Nine Brazilian wheat flours (Triticum aestivum) classified by rheological gluten force were used to extract the proteins. Extracts were pooled together by technological qualities in low (LW), medium (MD), and superior (SP). Peptides were analyzed by nanoUPLC and mass spectrometry multiplex method (MSE). Collectively, 3545 peptides and 1297 proteins were identified, and 116 proteins were found differentially abundant. Low molecular weight glutenin subunits (LMW-GS) were found up-regulated only in SP samples. Proteins related to wheat grain hardness, such as puroindoline-A, were found in significant concentration in LW samples. After domain prediction, LW presented a different pattern with a lower abundance of functional domains, and SP presented chaperones, known to be involved in adequate folding of the storage proteins. NanoUPLC-MSE was efficient in analyzing and distinguishing the proteomic pattern of wheat flours from different qualities, pointing out the differentially abundant gluten proteins and providing a better understanding of wheat flour quality. SignificanceCommon wheat is one of the most important staple food sources in the world. The improvement and comprehension of wheat quality has been a major objective of plant breeders and cereal chemists. Our findings highlighted the application of a modern proteomic approach to obtain a better understanding of the impact of gluten proteins on the technological quality of different wheat flours. The obtained data revealed different abundances of wheat quality-related proteins in superior quality flours when compared with samples of low rheological properties. In addition, multivariate statistical analysis clearly distinguished the flours of different qualities. This work contributes to the consolidation of research in the field of wheat technological quality.

Overview of Lipidomic Analysis of Triglyceride Molecular Species in Biological Lipid Extracts.

Triglyceride (TG) is a class of neutral lipids, which functions as an energy storage depot and is important for cellular growth, metabolism, and function. The composition and content of TG molecular species are crucial factors for nutritional aspects in food chemistry and are directly associated with several diseases, including atherosclerosis, diabetes, obesity, stroke, etc. As a result of the complexities of aliphatic moieties and their different connections/locations to the glycerol backbone in TG molecules, accurate identification of individual TG molecular species and quantitative assessment of TG composition and content are particularly challenging, even at the current stage of lipidomics development. Herein, methods developed for analysis of TG species, such as liquid chromatography-mass spectrometry with a variety of columns and different mass spectrometric techniques, shotgun lipidomics approaches, and ion-mobility-based analysis, are reviewed. Moreover, the potential limitations of the methods are discussed. It is our sincere hope that the overviews and discussions can provide some insights for researchers to select an appropriate approach for TG analysis and can serve as the basis for those who would like to establish a methodology for TG analysis or develop a new method when novel tools become available. Biologically accurate analysis of TG species with an enabling method should lead us toward improving the nutritional quality, revealing the effects of TG on diseases, and uncovering the underlying biochemical mechanisms related to these diseases.

Evaluation of diagnostic accuracy of biomarkers of inborn errors of metabolism in sick neonates: A prospective observational study

ObjectiveTo evaluate the diagnostic accuracy of a set of predefined biomarkers (index test) in diagnosing diseases targeted in expanded newborn screening (ENS) namely organic acidemias, fatty acid oxidation disorders, and amino acid disorders. MethodsThis was a prospective study. The study population consisted of out born neonates admitted to a teaching hospital for the study duration of 12 months. The presence of any of the predefined biomarkers was considered index test positive. Tandem Mass Spectrometry on dried blood samples along with urinary gas chromatography mass spectrometry (GCMS) was considered the gold standard (reference test) for diagnosis of diseases targeted in ENS. ResultsA total of 783 out born neonates were evaluated using the index test and 30 tested positive, out of which, 18 were reference test positive. All index test negative neonates (n = 30) were reference test negative. The index test had a sensitivity of 100%, specificity of 71.42%, with 60% positive predictive value and 100% negative predictive value. The area under ROC curve for the index test was 80%. ConclusionsIn the absence of universal screening programs, the evaluated biomarkers (index test) can be useful to decide which cases should be selectively referred for mass spectrometric techniques. Further multicentric studies are required to assess these biomarkers before incorporating them in national programs.

Structural Characterization of Daunomycin-Peptide Conjugates by Various Tandem Mass Spectrometric Techniques.

The use of peptide-drug conjugates has generated wide interest as targeted antitumor therapeutics. The anthracycline antibiotic, daunomycin, is a widely used anticancer agent and it is often conjugated to different tumor homing peptides. However, comprehensive analytical characterization of these conjugates via tandem mass spectrometry (MS/MS) is challenging due to the lability of the O-glycosidic bond and the appearance of MS/MS fragment ions with little structural information. Therefore, we aimed to investigate the optimal fragmentation conditions that suppress the prevalent dissociation of the anthracycline drug and provide good sequence coverage. In this study, we comprehensively compared the performance of common fragmentation techniques, such as higher energy collisional dissociation (HCD), electron transfer dissociation (ETD), electron-transfer higher energy collisional dissociation (EThcD) and matrix-assisted laser desorption/ionization–tandem time-of-flight (MALDI-TOF/TOF) activation methods for the structural identification of synthetic daunomycin-peptide conjugates by high-resolution tandem mass spectrometry. Our results showed that peptide backbone fragmentation was inhibited by applying electron-based dissociation methods to conjugates, most possibly due to the “electron predator” effect of the daunomycin. We found that efficient HCD fragmentation was largely influenced by several factors, such as amino acid sequences, charge states and HCD energy. High energy HCD and MALDI-TOF/TOF combined with collision induced dissociation (CID) mode are the methods of choice to unambiguously assign the sequence, localize different conjugation sites and differentiate conjugate isomers.

Statins for the prevention of proliferative vitreoretinopathy: cellular responses in cultured cells and clinical statin concentrations in the vitreous

Proliferative vitreoretinopathy (PVR) with rhegmatogenous retinal detachment (RRD) is a complex inflammatory ocular disease. Statins are widely used cholesterol-lowering drugs with putative anti-inflammatory properties. In this study, we have explored their efficacy in controlling post-surgical PVR formation. Simvastatin (SIM), atorvastatin (ATV), or rosuvastatin (RSV) were added to cultures of human retinal pigment epithelial cells (ARPE-19) prior to exposure with the bacterial lipopolysaccharide (LPS), and the production of pro-inflammatory cytokines (IL-6, IL-8, MCP-1) was examined using an enzyme-linked immunosorbent assay. In addition, the concentrations of simvastatin, atorvastatin, rosuvastatin, and their metabolites were measured from the vitreal samples of 20 patients undergoing vitrectomy (16 of them receiving oral statin therapy) using an ultra-performance liquid chromatography-tandem mass spectrometer technique. All statins alleviated LPS-induced inflammation at 5 µM concentration in the ARPE-19 cell cultures. Statin levels in the vitreous samples ranged from 6 to 316 pg/mL (ca. 0.1–7 M−10). Vitreal statin concentrations were similar to the typical steady-state unbound statin concentrations in plasma, indicating that only the unbound drug distributes from the blood circulation into the vitreous. Pharmacokinetic simulations of the intravitreal delivery of statins indicate that the measured clinical statin concentrations could be maintained with existing drug delivery technologies for months. Our results suggest that intravitreal statin therapy may have the potential in alleviating the risk of post-surgical PVR.

Synthesis of New Series of Phenyldiazene Based Metal Complexes for Designing Most Active Antibacterial and Antifungal Agents

In this study, In Vitro antibacterial and antifungal activities of azo series based on transition metal complexes (Cu2+, Zn2+, Mn2+, Co2+ and Ni2+) with already our reported ligands named as; [(E)-1-(1, 3-dioxolan-2-yl)-2-phenyldiazene] (K-1), [(E)-1-(1, 3-dioxolan-2-yl)-2-(4-methylphenyl)diazene] (K-2), 2-[(E)-phenyl diazenyl]-1H-benzimidazole] (K-3), [(E)-1-(1, 3-dioxolan-2-yl)-2-(4-ethylphenyl)diazene] (K-4), and [(E)-1-(1, 3-dioxolan-2-yl)-2-(2-methylphenyl)-diazene] (K-5) were studied. FTIR 1H-NMR and mass spectrometric techniques were applied for interpretation of synthesized complexes. 4.05-4.07 ppm chemical shift appearance of azo group confirms azo coupling with transition metal complexes. N=N, C-H, C-N and C-O groups are also confirmed by FTIR which exhibited peaks at 1400-1500, 2090-3090, 1100-1180, 1010-1060 and 625-780 cm-1. Furthermore, mass spectroscopic data also gives strong indication for the synthesis of metal complexes. All the newly synthesized complexes were screened for their antibacterial and antifungal activities. Antibacterial and antifungal activity against S. aureus, E.coli and A.niger, A.ustus and C.albican at conc. 250 and#181;g/ml showed excellent activity by K-1 complexes (Co2+, Cu2+, Ni2+), K-5 complexes (Zn2+, Mn2+, Cu2+), K-2 complexes (Co2+, Cu2+, Mn2+) and K-3 (Zn2+, Mn2+, Co2+, Cu2+) as compared to standard drug (Ampicillin). Hence, based on this study, it was concluded that these azo based complexes may act as a platform for designing more active antibacterial and antifungal agents.

Determination of picogram amounts of uranium in micrometre-sized particles by isotope dilution mass spectrometry

Micro-manipulated uranium micrometer-sized particles under optical microscope, measured at picogram level by two mass spectrometric techniques.

Synthesis of New Series of Phenyldiazene Based Metal Complexes for Designing Most Active Antibacterial and Antifungal Agents

In this study, In Vitro antibacterial and antifungal activities of azo series based on transition metal complexes (Cu2+, Zn2+, Mn2+, Co2+ and Ni2+) with already our reported ligands named as; [(E)-1-(1, 3-dioxolan-2-yl)-2-phenyldiazene] (K-1), [(E)-1-(1, 3-dioxolan-2-yl)-2-(4-methylphenyl)diazene] (K-2), 2-[(E)-phenyl diazenyl]-1H-benzimidazole] (K-3), [(E)-1-(1, 3-dioxolan-2-yl)-2-(4-ethylphenyl)diazene] (K-4), and [(E)-1-(1, 3-dioxolan-2-yl)-2-(2-methylphenyl)-diazene] (K-5) were studied. FTIR 1H-NMR and mass spectrometric techniques were applied for interpretation of synthesized complexes. 4.05-4.07 ppm chemical shift appearance of azo group confirms azo coupling with transition metal complexes. N=N, C-H, C-N and C-O groups are also confirmed by FTIR which exhibited peaks at 1400-1500, 2090-3090, 1100-1180, 1010-1060 and 625-780 cm-1. Furthermore, mass spectroscopic data also gives strong indication for the synthesis of metal complexes. All the newly synthesized complexes were screened for their antibacterial and antifungal activities. Antibacterial and antifungal activity against S. aureus, E.coli and A.niger, A.ustus and C.albican at conc. 250 and#181;g/ml showed excellent activity by K-1 complexes (Co2+, Cu2+, Ni2+), K-5 complexes (Zn2+, Mn2+, Cu2+), K-2 complexes (Co2+, Cu2+, Mn2+) and K-3 (Zn2+, Mn2+, Co2+, Cu2+) as compared to standard drug (Ampicillin). Hence, based on this study, it was concluded that these azo based complexes may act as a platform for designing more active antibacterial and antifungal agents.

Rapid, in situ detection of chemical warfare agent simulants and hydrolysis products in bulk soils by low-cost 3D-printed cone spray ionization mass spectrometry.

Chemical warfare agents (CWAs) are toxic chemicals that have been used as disabling or lethal weapons in war, terrorist attacks, and assasinations. The Chemical Weapons Convention (CWC) has prohibited the use, development, production, and stockpiling of CWAs since its initiation in 1997, however, the threat of deployment still looms. Detection of trace CWAs post-deployment or post-remediation, in bulk matrices such as soil, often requires lengthy sample preparation steps or extensive chromatographic separation times. 3D-printed cone spray ionization (3D-PCSI), an ambient ionization mass spectrometric (MS) technique, provides a rapid, simple, and low-cost method for trace CWA analysis in soil matrices for both in-laboratory and in-field detection. Described here is the utilization of conductive 3D-printed cones to perform both rapid sampling and ionization for CWA simulants and hydrolysis products in eight solid matrices. The analysis of trace quantities of CWA simulants and hydrolysis products by 3D-PCSI-MS coupled to both a commercial benchtop system and a field-portable MS system is detailed. Empirical limits of detection (LOD) for CWA simulants on the benchtop MS ranged from 100 ppt to 750 ppb and were highly dependant on solid matrix composition, with the portable system yielding similar spectral data from alike matrices, albeit with lower sensitivity.

Fragmentation of threonine under low-energy electron impact

New data have been obtained on the fragmentation of a threonine ( $$\hbox {C}_{{4}}\hbox {H}_{{9}}\hbox {NO}_{{3}}$$ ) molecule (i.e., ionized product formation) under low-energy electron impact. This was accomplished using a mass spectrometric experimental technique in combination with an extensive DFT-theory approach. Based on the results, the main pathways of threonine molecule’s fragment yield are suggested. The absolute values of the appearance energies for some ion fragments have been experimentally measured, theoretically calculated, and analyzed.

Synthesis, Spectroscopic, Molecular Modeling and Anti-Fungal Studies of Some Divalent Metal Complexes of 4-Hydroxyacetophenone Isonicotinoyl Hydrazone

A novel ligand N-4-hydroxyacetophenone isonicotinoyl hydrazone and its manganese(II) and nickel(II) metal complexes have been synthesized. The synthesized Schiff base and its metal complexes have been characterized by physical state determination, melting point and solubility measurements in different solvents, infrared, proton nuclear magnetic resonance, mass spectrometric and powder X-ray spectroscopic techniques. The thermal properties of the prepared compounds were obtained from TG/DTG measurements. On the basis of the analytical techniques, the ligand was found to be bidentate in nature coordinating to the metal ions through the azomethine nitrogen and carbonyl oxygen atoms leading to distorted octahedral geometries of the metal complexes which were modeled using MM2 force field. The ligand and its metal(II) complexes were evaluated for antifungal activity against Aspergillus fumigatus, Aspergillus niger, Candida albicans and Rhizopus stolonifera. The antifungal evaluation results revealed an enhanced activity upon coordination of the ligand with the metal(II) ions. The activity of the metal complex to the tested fungal strains was in the order Ni(II) > Mn(II).

Development and validation of an automated solid-phase extraction-LC-MS/MS method for the bioanalysis of fluoxetine in human plasma.

A wide-range, specific, and precise liquid chromatography tandem mass spectrometric (LC-MS/MS)technique for quantifying fluoxetine (FLX) in human plasma was developed using the RapidTrace® automated solid-phase extraction (SPE) method; the analyte and internal standard (IS) were extricated on Oasis MCX SPE cartridges. Acetonitrile and 5 mM ammonium formate buffer (90:10 v/v) were used as mobile phase to achieve chromatographic separation on the reverse phase (C18 column). The analyte and IS were ionized using +ve electrospray ionization approach which was further traced by multiple-reaction monitoring on a tandem mass spectrometer. To quantify the FLX and FLX-d5, the parent-to-daughter ion transition of m/z of 310.0/44.1 and 315.0/44.0 was used, respectively. The method demonstrated a linear active limit of 0.20–30 ng/ml with recoveries ranging from 63.04% to 79.39% for quality control samples and 61.25% for IS samples. The concentrations over the calibration range demonstrated acceptable precision and accuracy. Due to the high inconsistency of the FLX concentration data, the minimum threshold of the assay was kept at 0.20 ng/ml. The flow rate was maintained at 500 μL/min, and the time for sample analysis for each injection was 3.5 min. The method was found to be specific, sensitive, and faster with minimum utilization of organic solvents and was utilized further for metabolic and pharmacokinetic studies.

Synthetic Cannabinomimetics: A Brief History and the Challenges They Pose for the Forensic Chemist

Since the first detection of synthetic cannabinomimetics in herbal smoking blends in 2008 the clandestine production of these compounds, based on seizure data, increased in number every year until ~2012. In recent years there has been a decline in synthetic cannabinomimetic production both in number and diversity. The synthetic details of the first generation cannabinoids were documented in the scientific and medical literature making production comparatively simple. Subsequent generations of synthetic cannabinoids involved more complex but still very practicable synthetic chemistry. This resulted in a period of rapid growth in synthetic cannabinoids creating a health crisis and problems for forensic chemists faced with many substances for which no certified reference materials existed. Routine forensic chemistry laboratories were well practiced at identifying known drugs using chromatographic–mass spectrometric techniques and comparison to reference materials. However as synthetic cannabinomimetics, often referred to in the literature as synthetic cannabinoids, appeared in large numbers, few laboratories were equipped with the nuclear magnetic resonance (NMR) spectrometers and high resolution mass spectrometers (HRMS) required for identification of unknown substances. These developments also challenged public prosecutors for opinions from forensic experts as to the legality or otherwise of these novel drugs.

MALDI-MS: A Powerful but Underutilized Mass Spectrometric Technique for Exosome Research

MALDI-MS: A Powerful but Underutilized Mass Spectrometric Technique for Exosome Research

Purification, characterization, immobilization and kinetic studies of catalase from a novel source Sechium edule

AbstractA catalase from a novel source Sechium edule (squash) has been purified to homogeneity using ammonium sulfate fractional precipitation, dialysis, and anion exchange chromatography on Diethylaminoethyl (DEAE) cellulose in sodium acetate buffer pH 6.0. The purity of the enzyme was analyzed by SDS‐PAGE. The molecular weight of the enzyme using the SDS‐PAGE method was found to be 55 kDa with specific activity 6.35 U/mg. The molecular weight of the enzyme was further confirmed by the INTACT mass spectrometric technique and found to be 52.5 kDa. The Reinheitzahl (Rz) value of the enzyme was 1.5. The MALDI‐TOF analysis of the purified enzyme showed that it contains 529 amino acid residues. The Km, Vmax, optimum pH, and optimum temperature of the free enzyme using H2O2 as the substrate were found to be 0.03 mM, 200 μmol/min, 7.6, and 24°C, respectively. The purified enzyme was immobilized on chitosan beads which was prepared by extracting the chitosan from Cornu aspersum (garden snail) having highest degree of deacetylation%. The kinetic characteristics, Km, Vmax, optimum pH, and optimum temperature of the immobilized catalase were found to be 0.065 mM, 250 μmol/min, 7.6, and 41°C, respectively. The immobilized catalase is more thermostable in comparison to free catalase.