Transform-ion Cyclotron Resonance Mass Spectrometry Research Articles

The identification of selenopolythionates in aqueous solutions by electrospray ionization-Fourier transform-ion cyclotron resonance-mass spectrometry

Selenosulfate (SeSO32−) has been shown to occur in certain industrial process waters, and selenopolythionates (SenSxO62−) can be suspected to form from SeSO32− via oxidative or addition reactions. We report here the first observation of selenopolythionates in waters by mass spectrometry. The high mass accuracy and ultra-high resolution of Fourier transform-ion cyclotron resonance-mass Spectrometry with electrospray ionization (ESI-FT-ICR-MS) were used to analyze the isotope patterns of selenium (Se), sulfur (S), and oxygen (O) satellites, in order to provide unequivocal determination of the molecular sum formula of three different selenopolythionates. An aged aqueous solution of SeSO32− was shown to contain the sodium adducts of selenotrithionate (NaSeS2O6−), diselenotetrathionate (NaSe2S2O6−), and triselenopentathionate (NaSe3S2O6−). The identity of these ions was confirmed by accurate mass determination (Δ m/z < 3 ppm error) and by isotopic intensity ratio analysis of the [MIS+2] satellites. Furthermore, Collision Induced Dissociation (CID) was applied to selenotrithionate to distinguish between isomers, and the fragmentation mass spectrum reveals that the Se atom in NaSeS2O6− is located in the middle of the chalcogen chain. Ion chromatographic analysis of the analyzed selenosulfate solutions indicates that selenopolythionates are not suitable for determination by common separations employed for Se speciation analysis, which emphasizes the value of ESI-FT-ICR-MS for complete qualitative characterization of trace element speciation in solution.

Vacuum Pyrolysis of Hybrid Poplar Milled Wood Lignin with Fourier Transform-Ion Cyclotron Resonance Mass Spectrometry Analysis of Feedstock and Products for the Elucidation of Reaction Mechanisms

The pyrolysis of lignocellulosic materials is a promising technique to produce fuels and chemicals. It is well known that the most abundant products of lignin pyrolysis are oligomeric molecules, kn...

Low-temperature oxidation of heavy crude oil characterized by TG, DSC, GC-MS, and negative ion ESI FT-ICR MS

Low-temperature oxidation (LTO) is of great significance for the subsequent oxidation reactions and oil recovery during in-situ combustion. The paper brings an in-depth analysis of crude oil LTO that is still not well understood. Firstly, one Xinjiang heavy oil was subjected to LTO reactions under different temperatures conducted in an oxidation reactor. The combustion behaviors of the oxidized oils were then investigated by thermogravimetry and differential scanning calorimetry. The Friedman and Ozawa-Flynn-Wall methods were adopted to perform combustion kinetic analysis of the oxidized oils. Subsequently, both gas chromatograph-mass spectroscopy and negative ion electrospray Fourier transform-ion cyclotron resonance mass spectrometry were introduced as a new route to investigate the compositional changes of crude oil caused by LTO. The condensation of aromatics as well as aromatization and condensation of other compounds was intensified from 40 to 200 °C. Chain saturated aliphatic, monocyclic, bicyclic, and tricyclic naphthenic acids were the main acidic components in the oxidized oils. The relative abundance of chain saturated aliphatic acids and O1 species was decreased from 40 to 200 °C, whereas that of tricyclic naphthenic acids and O3 species was increased. Finally, we summarized LTO reaction pathways of crude oil, which helped to understand LTO mechanisms.

Metabolome profile of Negi-Nira chive, an interspecies hybrid of green spring onion (Allium fistulosum) and Chinese chive (A. tuberosum).

Metabolome analysis of flavored vegetables, green spring onion (Allium fistulosum), Chinese chive (A. tuberosum), and their interspecies hybrid Negi-Nira chive, was conducted using liquid chromatography-Fourier transform ion cyclotron resonance-mass spectrometry, with ca. 2 ppm mass accuracy. Ion peaks in the chromatograms of four biological replicates of the vegetable leaves were processed using the alignment software PowerGet for metabolite comparison, from which we obtained the potential chemical formulae. In total, 860 ion peaks were reproducibly detected; of these, 506, 525, and 336 peaks were found in the hybrid, A. tuberosum, and A. fistulosum, respectively. There were 130 peaks specific to the hybrid; from these, 31 metabolites were annotated by searching compound databases. The sulfur-containing compounds and flavonoids were further analyzed using bioinformatics, to examine the sulfur metabolism of Allium volatiles and the flavonoid pathways in these species. In conclusion, our metabolome analysis of this interspecies hybrid and its parents provides a unique opportunity to elucidate their metabolic background.

Distribution of nitrogen and oxygen compounds in shale oil distillates and their catalytic cracking performance

The positive- and negative-ion electrospray ionization (ESI) coupled with Fourier transform-ion cyclotron resonance mass spectrometry (FT-ICR MS) was employed to identify the chemical composition of heteroatomic compounds in four distillates of Fushun shale oil, and their catalytic cracking performance was investigated. There are nine classes of basic nitrogen compounds (BNCs) and eleven classes of non-basic heteroatomic compounds (NBHCs) in the different distillates. The dominant BNCs are mainly basic N1 class species. The dominant NBHCs are mainly acidic O2 and O1 class species in the 300–350 °C, 350–400 °C, and 400–450 °C distillates, while the neutral N1, N1O1 and N2 compounds become relatively abundant in the > 450 °C fraction. The basic N1 compounds and acidic O1 and O2 compounds are separated into different distillates by the degree of alkylation (different carbon number) but not by aromaticity (different double-bond equivalent values). The basic N1O1 and N2 class species and neutral N1 and N2 class species are separated into different distillates by the degrees of both alkylation and aromaticity. After the catalytic cracking of Fushun shale oil, the classes of BNCs in the liquid products remain unchanged, while the classes and relative abundances of NBHCs vary significantly.

Transformation mechanisms of refractory organic matter in mature landfill leachate treated using an Fe0-participated O3/H2O2 process

An Fe0-participated O3/H2O2 (Fe0-O3/H2O2) process was applied to remove refractory organic matter (OM) in semi-aerobic aged refuse biofilter (SAARB) leachate arising from treating mature landfill leachate. The degradation and transformation characteristics of refractory OM were revealed at molecular level. Removal efficiencies of aromatic substances were 63.55% by the Fe0-O3/H2O2 process (much higher than in other single or binary processes), and fulvic- and humic-like substances were more effectively degraded by this process than by other treatments. According to Fourier transform-ion cyclotron resonance mass spectrometry (FT-ICR MS), 6645 categories of OM in SAARB leachate were identified. Although there was little difference in number of OM categories after treatment using the single-O3 and Fe0-O3/H2O2 processes, Fe0-O3/H2O2 process can better reduce OM relative abundance. It is noteworthy that the Fe0-O3/H2O2 process more effectively degraded CHONS compounds than the single-O3 process, while also producing more CHO compounds having higher bio-availability. The enhanced degradation efficiency of the Fe0-O3/H2O2 process were attributed to the formation of the Fenton process initiated by leached Fe2+ and H2O2. The heterogeneous catalytic effect from iron (hydro) oxides for O3/H2O2 also increased the treatment capacity of the Fe0-O3/H2O2 process, resulting in better total organic carbon removal. The Fe0-O3/H2O2 process is an efficient method for removing refractory OM in SAARB leachate.

NSO-compounds in oil-bearing fluid inclusions revealed by FT-ICR-MS in APPI (+) and ESI (−) modes: A new method development

The origins of hydrocarbons occurring in oil-bearing fluid inclusions (FIs) have been studied in detail over the last four decades, but very little is known about co-occurring nitrogen, sulfur and oxygen (NSO)-containing compounds. Here, we outline a new method for gathering valuable information on NSO-compounds using the Fourier Transform-Ion Cyclotron Resonance-Mass Spectrometry (FT-ICR-MS) in combination with Atmospheric Pressure Photoionization in positive ion mode (APPI (+)) and Electrospray Ionization in negative ion mode (ESI (−)). A key element was to develop a rigorous acid-free cleaning protocol to make oil inclusions from a broad range of host materials accessible to the very sensitive FT-ICR-MS technique. Although oil contamination from surrounding organic matter could not be entirely eliminated, the procedure enables distinction of external contaminants and identification of affected NSO-compound classes allowing a conditional interpretation of the FT-results of FI samples, especially for compounds measured in the APPI (+) mode. First insights into the high molecular weight hydrocarbons and NSO-compounds in FI oils are presented here using examples from Germany, Tunisia, Pakistan and Mexico.

Probing key organic substances driving new particle growth initiated by iodine nucleation in coastal atmosphere

Abstract. Unlike the deep understanding of highly oxygenated organic molecules (HOMs) driving continental new particle formation (NPF), little is known about the organic compounds involved in coastal and open-ocean NPF. On the coastline of China we observed intense coastal NPF events initiated by iodine nucleation, but particle growth to cloud condensation nuclei (CCN) sizes was dominated by organic compounds. This article reveals a new group of C18,30HhOoNn and C20,24,28,33HhOo compounds with specific double-bond equivalents and oxygen atom numbers in new sub 20 nm coastal iodine particles by using ultrahigh-resolution Fourier transform–ion cyclotron resonance mass spectrometry (FT-ICR-MS). We proposed these compounds are oxygenated or nitrated products of long-chain unsaturated fatty acids, fatty alcohols, nonprotein amino acids or amino alcohols emitted mutually with iodine from coastal biota or biologically active sea surface. Group contribution method estimated that the addition of –ONO2, –OH and –C=O groups to the precursors reduced their volatility by 2–7 orders of magnitude and thus made their products condensable onto new iodine particles in the coastal atmosphere. Nontarget MS analysis also provided a list of 440 formulas of iodinated organic compounds in size-resolved aerosol samples during the iodine NPF days, which facilitates the understanding of unknown aerosol chemistry of iodine.

Characterization of RDX and HMX explosive adduct ions using ESI FT-ICR MS.

Investigation of two common explosives such as cyclonite (RDX) and cyclotetramethylenetetranitramine (HMX) using a mass spectrometer with ultrahigh resolution and accuracy has not been comprehensively performed. Here, ultrahigh mass accuracy 15-T Fourier transform-ion cyclotron resonance mass spectrometry (FT-ICR MS) spectra were utilized to comprehensively characterize the adduct ions of RDX and HMX. Two different ionization sources such as a conventional electrospray ionization (ESI) source and a chip-based static nano-ESI source were used to investigate the adduct ions of RDX and HMX. The ESI-MS analyses of two explosives in negative ion mode provide some adduct ions of RDX and HMX even without prior addition of their corresponding anions. A total of six types of adduct ion were characterized: [M + Cl]- , [M + HCOO]- , [M + NO2 ]- , [M + CH3 COO]- , [M + NO3 ]- , and [M + C3 H5 O3 ]- , where M is either RDX or HMX. The ultrahigh accuracy of the 15-T FT-ICR MS was utilized to distinguish two closely spaced peaks representing the monoisotopic [M + NO2 ]- and second isotopic [M + HCOO]- ions, thereby enabling the discovery of a [M + NO2 ]- adduct ion in the ESI analysis of RDX or HMX. [M + NO2 ]- and [M + CH3 COO]- adduct ions were only observed when using a static nano-ESI source. It is the first report explaining the discovery of [M + NO2 ]- adduct ion in the ESI-MS analyses of RDX and HMX.

Precise maturity assessment over a broad dynamic range using polycyclic and heterocyclic aromatic compounds

The construction and reliable application of maturation indices is extremely important in deep Earth exploration, yet predicting levels of maturation on a molecular level, especially at overmature stages, is still a major challenge. Here, we report robust, broad ranging and precise maturity parameters that were developed using a continuous core of thermally overmature lacustrine deposits (Shahezi Fm.) from the deep Songke-2 Well (SK-2), Songliao Basin, China, augmented by shallow cores of lower maturity marine deposits (Posidonia Shale) from the Hils Syncline, Germany.The novel indices presented here are based on the general process of thermally-induced cyclization, aromatization and aliphatic chain cracking of hundreds to thousands of compounds during maturation. The newly developed parameters, with an extremely broad dynamic range extending from catagenesis and into metagenesis (vitrinite reflectances (Ro) range from 0.9% to 2.2%), are based on polycyclic and heterocyclic aromatic compounds measured using Fourier transform-ion cyclotron resonance-mass spectrometry (FT-ICR-MS). The high coefficient of correlations between the new maturity parameters with Ro and Tmax demonstrate their utility for assessing precisely the thermal maturity of overmature shales.

Identification of Fatty Acids and Triacylglycerols in Schisandrae chinensis fructus Oil

Schisandrae chinensis fructus (Wuweizi) contains many triacylglycerols (TAGs). Therefore, it is inevitable that these TAGs will be part of Chinese medical preparations of Schisandrae chinensis fructus. It is important to identify TAGs in Schisandrae chinensis fructus. Fatty acids in Schisandrae chinensis fructus oil were identified by gas chromatography−mass spectrometry (GC−MS) after transesterification. TAGs were determined by liquid chromatography−mass spectrometry (LC−MS) and confirmed by high-resolution Fourier transform-ion cyclotron resonance-mass spectrometry (FT−ICR−MS). Seven kinds of fatty acids were detected in Schisandrae chinensis fructus oil of which linoleic acid (L) and oleic acid (O) accounted for 93%. Also, 7 TAGs were recognized in the oil. LLL, OLL, OOL and PLL were the main components (P corresponds to palmitic acid). The LLL composed approximately half of the oil of Schisandrae chinensis fructus by mass. The composition of fatty acids and TAGs in Schisandrae chinensis fructus was determined by GC−MS, LC−MS and FT−ICR−MS.

Genome-Guided Mass Spectrometry Expedited the Discovery of Paraplantaricin TC318, a Lantibiotic Produced by Lactobacillus paraplantarum Strain Isolated From Cheese.

The quest for potent alternatives to the currently used antimicrobials is urged by health professionals, considering the rapid rise in resistance to preservatives and antibiotics among pathogens. The current study was initiated to search for novel and effective bacteriocins from food microbes, preferably lactic acid bacteria (LAB), for potential use as preservatives. Advances in genome-guided mass spectrometry (MS) were implemented to expedite identifying and elucidating the structure of the recovered antimicrobial agent. A LAB strain, OSY-TC318, was isolated from a Turkish cheese, and the crude extract of the cultured strain inhibited the growth of various pathogenic and spoilage bacteria such as Bacillus cereus, Clostridium sporogenes, Enterococcus faecalis, Listeria monocytogenes, Salmonella enterica ser. Typhimurium, and Staphylococcus aureus. The antimicrobial producer was identified as Lactobacillus paraplantarum using MS biotyping and genomic analysis. Additionally, L. paraplantarum OSY-TC318 was distinguished from closely related strains using comparative genomic analysis. Based on in silico analysis, the genome of the new strain contained a complete lantibiotic biosynthetic gene cluster, encoding a novel lantibiotic that was designated as paraplantaricin TC318. The bioinformatic analysis of the gene cluster led to the prediction of the biosynthetic pathway, amino acid sequence, and theoretical molecular mass of paraplantaricin TC318. To verify the genomic analysis predictions, paraplantaricin TC318 was purified from the producer cellular crude extract using liquid chromatography, followed by structural elucidation using Fourier transform ion cyclotron resonance MS analysis. This genome-guided MS analysis revealed that the molecular mass of paraplantaricin TC318 is 2,263.900 Da, its chemical formula is C106H133N27O22S4, and its primary sequence is F-K-S-W-S-L-C-T-F-G-C-G-H-T-G-S-F-N-S-F-C-C. This lantibiotic, which differs from mutacin 1140 at positions 9, 12, 13, and 20, is considered a new member of the epidermin group in class I lantibiotics. In conclusion, the study revealed a new L. paraplantarum strain producing a novel lantibiotic that is potentially useful in food and medical applications.

Systematic Evaluation of Normalization Methods for Glycomics Data Based on Performance of Network Inference.

Glycomics measurements, like all other high-throughput technologies, are subject to technical variation due to fluctuations in the experimental conditions. The removal of this non-biological signal from the data is referred to as normalization. Contrary to other omics data types, a systematic evaluation of normalization options for glycomics data has not been published so far. In this paper, we assess the quality of different normalization strategies for glycomics data with an innovative approach. It has been shown previously that Gaussian Graphical Models (GGMs) inferred from glycomics data are able to identify enzymatic steps in the glycan synthesis pathways in a data-driven fashion. Based on this finding, here, we quantify the quality of a given normalization method according to how well a GGM inferred from the respective normalized data reconstructs known synthesis reactions in the glycosylation pathway. The method therefore exploits a biological measure of goodness. We analyzed 23 different normalization combinations applied to six large-scale glycomics cohorts across three experimental platforms: Liquid Chromatography-ElectroSpray Ionization-Mass Spectrometry (LC-ESI-MS), Ultra High Performance Liquid Chromatography with Fluorescence Detection (UHPLC-FLD), and Matrix Assisted Laser Desorption Ionization-Furier Transform Ion Cyclotron Resonance-Mass Spectrometry (MALDI-FTICR-MS). Based on our results, we recommend normalizing glycan data using the ‘Probabilistic Quotient’ method followed by log-transformation, irrespective of the measurement platform. This recommendation is further supported by an additional analysis, where we ranked normalization methods based on their statistical associations with age, a factor known to associate with glycomics measurements.

Novel Strategy To Analyze Fourier Transform Ion Cyclotron Resonance Mass Spectrometry Data of Biomass Pyrolysis Oil for Oligomeric Structure Assignment

Among the most prominent challenges for the analysis of biomass pyrolysis products is the characterization of the abundant oligomer fraction of bio-oil. This fraction is principally made up of pyrolytic lignins and dehydrated, highly modified sugar oligomers, called humins, in liquid phase. An emerging technique for analysis of this oligomer fraction is high-resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), which allows for accurate determination of CxHyOz formulas for detected oligomers. Additionally, using simple dehydration and fragmentation reaction schemes, similar formulas can be developed from cellulose-, hemicellulose-, and lignin-derived oligomers, which are primary depolymerization products. In this study, FT-ICR MS analysis is coupled with combinatoric dehydration and fragmentation modeling to match experimentally detected bio-oil oligomers with hypothetical pathways for their formation during pyrolysis. In this way, we present a novel strategy by which oligomeric structures can be proposed for bio-oils. Using this approach, it becomes possible to advance the understanding of both the molecular structures comprising the bio-oil oligomer fraction and the pathways by which these structures form during biomass pyrolysis reactions.

Characterization of wastewater effluent organic matter with different solid phase extraction sorbents

Effluent organic matter (EfOM) from municipal wastewater treatment plants (WWTPs) has received increasing attention due to its impacts on natural and engineered aquatic systems. A comprehensive understanding of molecular compositions of EfOM is crucial for controlling its negative effects and effective removal of it. Fourier transform-ion cyclotron resonance mass spectrometry (FTICR MS) is a powerful method to characterize molecular compositions of EfOM. However, application of this powerful technique is very depending on the sample preparation procedures (i.e. solid phase extraction, SPE) for enrichment and desalting. In this study, a systematic comparison of the difference in molecular compositions of the EfOM extracted using eighteen different SPE sorbents (Envicarb, PPL, ENV, HLB, C18, C18OH, C8, PH, CH, WAX, WCX, MAX, MCX, CBA, C2, CN-E, NH2, and SI) was investigated. Molecular characterization using FTICR MS showed that non-polar sorbents (Envicarb, PPL, ENV, HLB, C18, C18OH) and mixed mode sorbents (WAX, WCX, MAX, MCX) prefer to extract more aromatic and unsaturated molecules, while strongly-polar (SI), mid-polar (CBA, NH2), and weakly non-polar (C2, CN-E) sorbents prefer to extract more aliphatic components. In addition, it is found that combining extracts of CBA, ENV, and EnviCarb sorbents might be a practical way to provide a comprehensive information of molecular composition of EfOM. The results reported in this study provide valuable information on molecular compositions of EfOM and the selectivity of EfOM by different SPE sorbents.

Molecular Absorption and Evolution Mechanisms of PM2.5Brown Carbon Revealed by Electrospray Ionization Fourier Transform–Ion Cyclotron Resonance Mass Spectrometry During a Severe Winter Pollution Episode in Xi'an, China

AbstractKnowledge of the molecular‐level chemistry of brown carbon (BrC) is important in reducing the uncertainties in aerosol radiative forcing. Time‐resolved ambient PM2.5samples were collected during a severe pollution episode in January 2017 over Xi'an, China for a comprehensive nontarget and full scanning of BrC molecules and their absorption properties using electrospray ionization Fourier transform–ion cyclotron resonance mass spectrometry combined with partial least squares regression analysis, which apportioned the overall ultraviolet absorption to individual molecules. The estimated absorption of CHNO and CHNOS molecules exhibited nighttime prevalence, whereas CHOS, CHNS, CHN, CHO, CHS, and CH molecules presented a dynamic trend. Carbon conjugation was positively correlated with estimated absorption by CHO and CHNO molecules, while exhibiting a mixed relationship with CHNOS. Higher nitrogen content was associated with enhanced light‐absorption properties of BrC molecules, while higher oxygen and sulfur content appeared to be associated with photobleaching during secondary transformation.

A novel biodegradation parameter derived from bicyclic sesquiterpanes for assessing moderate levels of petroleum biodegradation

Gas chromatography–mass spectrometry (GC–MS) and Fourier transform ion cyclotron resonance–mass spectrometry (FTICR–MS) analyses were performed on 39 heavy oils from an onshore basin in southeastern Mexico to investigate the influence of biodegradation on whole oil compositions. Among the biodegradation resistant C14–C16 bicyclic sesquiterpanes (bicyclanes), a rearranged C15 isomer (compound X) becomes relatively enriched with increasing biodegradation levels, contrasting with a reduction in the summed C14–C16 bicyclanes concentration but consistent with an enrichment of the bicyclic naphthenic acids revealed by FTICR–MS data. The concentration ratio of compound X over all the identified C15 bicyclane isomers (DMHD ratio) is proposed as a new biodegradation parameter. This ratio correlates well with the biodegradation ratios of 3-methylchrysene/methylchrysenes, benzonaphtho[1,2-d]thiophene/benzonaphtho[2,1-d]thiophene and those based on NSO compounds. Compound X has an additional ethyl group but one less methyl group compared to the drimane structure. A lessening of steric effects through demethylation can explain the refractory nature of compound X, and this forms the basis on which possible origins of compound X are discussed. Extensive biodegradation of the studied oil samples is implied by the alteration of polyaromatic hydrocarbons and NSO compounds. This suggests the relative enrichment of compound X can be used as a new indicator for heavy oil biodegradation at Peters and Moldowan biodegradation level (PM level) 4–5, when hopanes and steranes are still intact. Changes in the distribution patterns of some NSO compound species also suggest PM level 4–5.

Is It Possible to Measure Monobromamine Using Colorimetric Methods Based on the Berthelot Reaction, Like for Monochloramine?

Analytical methods based on the Berthelot reaction were recently adapted for determining monochloramine (MCA: NH2Cl) in freshwater. The specificity of the Berthelot reaction with regard to MCA is related to the need for two exchangeable hydrogen atoms to form indophenol blue. MCA can thus be distinguished from organic N-chloramines, which have only one exchangeable hydrogen atom. Monobromamine (MBA: NH2Br) may be formed during chlorination of seawater containing ammonium ions. Quantifying MBA is quite challenging and no method has been reported for its specific determination in seawater. As MBA also has two exchangeable hydrogen atoms, its reactivity might be analogous to that of MCA, but this hypothesis has never been investigated. The aim of this study was to examine the applicability of the so-called “indophenol method” for the determination of the MBA in freshwater and seawater samples. The reaction between MBA and Berthelot reagents was studied in both ultrapure water and artificial seawater. The reaction products were characterized by using gas chromatography coupled to mass spectrometry (GC–MS), Fourier transform-ion cyclotron resonance mass spectrometry (FT–ICR MS), and UV–vis spectroscopy. Results showed that colorimetric methods based on the Berthelot reaction were not suitable for measuring MBA in freshwater or seawater, since NH2Br reacts with alkaline phenol derivative via electrophilic substitution to form ortho- and para-brominated phenols instead of forming indophenol.

Molecular-level comparison study on microwave irradiation-activated persulfate and hydrogen peroxide processes for the treatment of refractory organics in mature landfill leachate

This study investigated the degradation of organics in mature leachate treated by microwave radiation-activated persulfate (MW/PS) and hydrogen peroxide (MW/H2O2) processes. Obvious synergistic effects existed in both the MW/PS and MW/H2O2 processes, but were significantly higher in the MW/PS process. Refractory organics were better degraded by the MW/PS process than the MW/H2O2 process due to the major contribution of SO4–. Moreover, according to Fourier transform-ion cyclotron resonance mass spectrometry coupled with electrospray ionization analysis results, the refractory organics (e.g. polycyclic aromatics (AI > 0.66), polyphenols (0.66 ≥ AI > 0.50)) were greatly degraded by both the MW/H2O2 and MW/PS processes, but the MW/PS process degraded dissolved organic matter (DOM) over a wider range than the MW/H2O2 process due to the different dominant radicals in the two processes. In addition, after reaction in the MW/PS process, the O/C ratio of DOM in the treated effluent showed an obvious increase, which can be mainly attributed to the reaction of sulfate radicals with the N- and S- containing compounds via single electron transfer.

Metallocomplex–Peptide Interactions Studied by Ultrahigh Resolution Mass Spectrometry

The OsII arene anticancer complex [(η6-bip)Os(en)Cl]+ (Os1-Cl; where bip = biphenyl and en = ethylenediamine) binds strongly to DNA1 and biomolecules. Here we investigate the interaction between Os1-Cl and the model protein, BSA, using ultrahigh resolution Fourier transform-ion cyclotron resonance mass spectrometry (FT-ICR MS). The specific binding location of Os1 on BSA was investigated with the use of collisionally activated dissociation (CAD) and electron capture dissociation (ECD). CAD MS/MS was found to dissociate the osmium complex from the metallo-peptide complex readily producing unmodified fragments and losing location information. ECD MS/MS, however, successfully retains the osmium modification on the peptides upon fragmentation allowing localization of metallocomplex binding. This study reveals that lysine is a possible binding location for Os1-Cl, apart from the expected binding sites at methionine, histidine, and cysteine. Using a nano liquid chromatography (nLC)-FT-ICR ECD MS/MS study, multiple binding locations, including the N-terminus and C-terminus of digested peptides, glutamic acid, and lysine were also revealed. These results show the multitargeting binding ability of the organo-osmium compound and can be used as a standard workflow for more complex systems, e.g., metallocomplex-cell MS analysis, to evaluate their behavior toward commonly encountered biomolecules.