N-dealkylation of amines during water disinfection - Revealing a new direction in the formation of disinfection by-products.

Among numerous disinfection by-products (DBP) forming during aqueous chlorination nitrogen containing species are of special concern due to their toxicological properties. Nevertheless, corresponding reaction products of these natural and anthropogenic compounds are not sufficiently studied so far. An interesting reaction involves dealkylation of the substituted amine moiety. Here we present the results of the comparative study of one-electron oxidation and aqueous chlorination of several aliphatic and aromatic amines. The reaction products were reliably identified with gas chromatography - high resolution mass spectrometry (GC-HRMS), high pressure liquid chromatography - electrospray ionization high resolution mass spectrometry HPLC-ESI/HRMS), and electrochemistry - electrospray ionization high resolution mass spectrometry (EC-ESI/HRMS). Certain similarities dealing with the formation of the corresponding aldehydes and substitution of alkyl groups at the nitrogen atom for hydrogen were shown for the studied processes. The mechanism of the substituted amines' aqueous chlorination involving one-electron oxidation is proposed and confirmed by the array of the observed reaction products. Alternative reactions taking place in conditions of aqueous chlorination, i.e. aromatic electrophilic substitution, may successfully compete with dealkylation and produce major products.

Longitudinal association of prepubertal urinary phthalate metabolite concentrations with pubertal progression among a cohort of boys.

BACKGROUND: Epidemiological studies have reported associations of anti-androgenic phthalate metabolite concentrations with later onset of male puberty, but few have assessed associations with progression. OBJECTIVES: We examined the association of prepubertal urinary phthalate metabolite concentrations with trajectories of pubertal progression among Russian boys. METHODS: At enrollment (ages 8-9 years), medical history, dietary, and demographic information were collected. At entry and annually to age 19 years, physical examinations including testicular volume (TV) were performed and spot urines collected. Each boy's prepubertal urine samples were pooled, and 15 phthalate metabolites were quantified by isotope dilution LC-MS/MS at Moscow State University. Metabolites of anti-androgenic parent phthalates were included: butylbenzyl (BBzP), di-n-butyl (DnBP), diisobutyl (DiBP), di(2-ethylhexyl) (DEHP) and diisononyl (DiNP) phthalates. We calculated the molar sums of DEHP, DiNP, and all AAP metabolites. We used group-based trajectory models (GBTMs) to identify subgroups of boys who followed similar pubertal trajectories from ages 8-19 years based on annual TV. We used multinomial and ordinal regression models to evaluate whether prepubertal log-transformed phthalate metabolite concentrations were associated with slower or faster pubertal progression trajectories, adjusting for covariates. RESULTS: 304 boys contributed a total of 752 prepubertal urine samples (median 2, range: 1-6) for creation of individual pools. The median length of follow-up was 10.0 years; 79% of boys were followed beyond age 15. We identified three pubertal progression groups: slower (34%), moderate (43%), and faster (23%) progression. A standard deviation increase in urinary log-monobenzyl phthalate (MBzP) concentrations was associated with higher adjusted odds of being in the slow versus faster pubertal progression trajectory (aOR 1.47, 95% CI 1.06-2.04). None of the other phthalate metabolites were associated with pubertal progression. CONCLUSIONS: On average, boys with higher concentrations of prepubertal urinary MBzP had a slower tempo of pubertal progression, perhaps attributable to the disruption of androgen-dependent biological pathways.

Application of clusterization algorithms for analysis of semivolatile pollutants in Arkhangelsk snow.

The best way to understand the environmental status of a certain region involves thorough non-target analysis, which will result in a list of pollutants under concern. Arkhangelsk (64° 32' N 40° 32' E, pop. ~ 344,000) is the largest city in the world to the north of the 60th parallel. Several industrial enterprises and the "cold finger" effect represent the major sources of air contamination in the city. Analysis of snow with comprehensive two-dimensional gas chromatography-high-resolution mass spectrometry allows detecting and quantifying the most hazardous volatile and semivolatile anthropogenic pollutants and estimating long-term air pollution. Target analysis, suspect screening, and non-target analysis of snow samples collected from ten sites within the city revealed the presence of several hundreds of organic compounds including 18 species from the US EPA list of priority pollutants. Fortunately, the levels of these compounds appeared to be much lower than the safe levels established in Russia. Phenol and dioctylphthalate could be considered as the pollutants of concern because their levels were about 20% of the safe thresholds. ChromaTOF® Tile, MetaboAnalyst software platform, and open-source software protocols were applied to process the obtained data. The obtained clusterization results of the samples were generally similar for various tools; however, each of them had certain peculiarities. Bis(2-ethylhexyl) hexanedioate, benzyl alcohol, phthalates, aniline, dinitrotoluenes, and fluoranthene showed the strongest influence on the clusterization of the studied samples. Possible sources of the major pollutants were proposed: car traffic and pulp and paper mills.

Halogen substitution reactions of halobenzenes during water disinfection.

Although being successfully applied all over the world for more than 100 years water disinfection by means of chlorination possesses certain drawbacks, first of all formation of hazardous disinfection by-products (DBP). Aromatic halogenated DBPs significantly contribute to the total organic halogen and developmental toxicity of chlorinated water. The present study deals with investigation of possible substitution of one halogen for another in aromatic substrates in conditions of aqueous chlorination/bromination. The reaction showed high yields especially in case of substrates with proper position of an activating group in the aromatic ring. Thus, ipso-substitution of iodine by chlorine is the main process of aqueous chlorination of para-iodoanisole. Oxidation of the eliminating I+ ions into non-reactive IO3- species facilitates the substitution. Oxidation of eliminating Br+ is not so easy while being highly reactive it attacks initial substrates forming polybrominated products. Substitution of iodine and bromine by chlorine may also involve migration of electrophilic species inside the aromatic ring resulting in larger number of isomeric DBPs. Substitution of chlorine by bromine in aromatic substrates during aqueous bromination is not so pronounced as substitution of bromine by chlorine in aqueous chlorination due to higher electronegativity of chlorine atom. However, formation of some chlorine-free polybrominated products proves possibility of that process.

Differentiation of Central Slovenian and Moscow populations of Rana temporaria frogs using peptide biomarkers of temporins family.

Skin secretion represents the only means of defense for the majority of frog species. That phenomenon is based on the fact that the main components of the secretion are peptides demonstrating greatly varying types of bioactivity. They fulfill regulatory functions, fight microorganisms and may be even helpful against predators. These peptides are considered to be rather promising pharmaceuticals of future generation as according to the present knowledge microorganisms are unlikely to develop resistance to them. Mass spectrometry sequencing of these peptides is the most efficient first step of their study providing reliably their primary structures, i.e., amino acids sequence and S-S bond motif. Besides discovering new bioactive peptides, mass spectrometry appears to be an efficient tool of taxonomy studies, allowing for distinguishing not only between closely related species, but also between populations of the same species. Application of several tandem mass spectrometry tools (CID, HCD, ETD, EThcD) available with Orbitrap mass analyzer allowed us to obtain full sequence of about 60 peptides in the secretion of Slovenian population of brown ranid frog Rana temporaria. The problem of sequence inside C-terminal cycle formed by two Cys and differentiation of isomeric Leu and Ile residues was done in top-down mode without any derivatization steps. Besides general biomarkers of Rana temporaria species, Central Slovenian population of Rana temporaria demonstrates six novel temporins and one brevinin 1, which may be treated as biomarkers of that population.

GC-HRMS with Complementary Ionization Techniques for Target and Non-target Screening for Chemical Exposure: Expanding the Insights of the Air Pollution Markers in Moscow Snow.

Environmental exposure assessment is an important step in establishing a list of local priority pollutants and finding the sources of the threats for proposing appropriate protection measures. Exposome targeted and non-targeted analysis as well as suspect screening may be applied to reveal these pollutants. The non-targeted screening is a challenging task and requires the application of the most powerful analytical tools available, assuring wide analytical coverage, sensitivity, identification reliability, and quantitation. Moscow, Russia, is the largest and most rapidly growing European city. That rapid growth is causing changes in the environment which require periodic clarification of the real environmental situation regarding the presence of the classic pollutants and possible new contaminants. Gas chromatography - high resolution time-of-flight mass spectrometry (GC-HR-TOFMS) with electron ionization (EI), positive chemical ionization (PCI), and electron capture negative ionization (ECNI) ion sources were used for the analysis of Moscow snow samples collected in the early spring of 2018 in nine different locations. Collection of snow samples represents an efficient approach for the estimation of long-term air pollution, due to accumulation and preservation of environmental contaminants by snow during winter period. The high separation power of GC, complementary ionization methods, high mass accuracy, and wide mass range of TOFMS allowed for the identification of several hundred organic compounds belonging to the various classes of pollutants, exposure to which could represent a danger to the health of the population. Although quantitative analysis was not a primary aim of the study, targeted analysis revealed that some priority pollutants exceeded the established safe levels. Thus, dibutylphthalate concentration was over 10-fold higher than its safe level (0.001 mg/L), while benz[a]pyrene concentration exceeded Russian maximal permissible concentration value of 5 ng/L in three samples. The large amount of information generated during the combination of targeted and non-targeted analysis and screening samples for suspects makes it feasible to apply the big data analysis to observe the trends and tendencies in the pollution exposome across the city.

Arctic snow pollution: A GC-HRMS case study of Franz Joseph Land archipelago.

Anthropogenic pollution of the Arctic atmosphere is of great interest due to the vulnerability of the Arctic ecosystems, as well as the processes of global transport and accumulation of atmospheric aerosols at high latitudes under conditions of cold climate. The present work throws light upon chemical composition of Arctic snow as a natural deposition matrix for atmospheric semi-volatile pollutants taken from the northernmost Arctic archipelago - Franz Josef Land, which is least affected by local sources of pollution and being a unique unstudied environmental object. The used methodology involved the liquid-liquid extraction of snow samples with dichloromethane and combination of targeted and non-targeted analyses of semi-volatile organic compounds with comprehensive two-dimensional gas chromatography - high-resolution mass spectrometry. While almost none of the known priority pollutants (except three dialkylphthalates) were identified in the studied samples, non-targeted screening revealed a specific class of biomass burning biomarkers - fatty amides with oleamide being the major component among them. Some peculiar organic pollutants (N,N-dimethylcyclohexylamine and N,N-dimethylbenzylamine) were identified in few samples. First results on the semi volatile pollutants in Franz Joseph Land snow were obtained using the most reliable GC × GC-HRMS non-target analysis.

Changes in the Metabolism of Sphingoid Bases in the Brain and Spinal Cord of Transgenic FUS(1-359) Mice, a Model of Amyotrophic Lateral Sclerosis.

The aim of this study was to evaluate changes in the content of sphingoid bases - sphingosine (SPH), sphinganine, and sphingosine-1-phosphate (SPH-1-P) - and in expression of genes encoding enzymes involved in their metabolism in the brain structures (hippocampus, cortex, and cerebellum) and spinal cord of transgenic FUS(1-359) mice. FUS(1-359) mice are characterized by motor impairments and can be used as a model of amyotrophic lateral sclerosis (ALS). Lipids from the mouse brain structures and spinal cord after 2, 3, and 4 months of disease development were analyzed by chromatography/mass spectrometry, while changes in the expression of the SPHK1, SPHK2, SGPP2, SGPL1, ASAH1, and ASAH2 genes were assayed using RNA sequencing. The levels of SPH and sphinganine (i.e., sphingoid bases with pronounced pro-apoptotic properties) were dramatically increased in the spinal cord at the terminal stage of the disease. The ratio of the anti-apoptotic SPH-1-P to SPH and sphinganine sharply reduced, indicating massive apoptosis of spinal cord cells. Significant changes in the content of SPH and SPH-1-P and in the expression of genes related to their metabolism were found at the terminal ALS stage in the spinal cord. Expression of the SGPL gene (SPH-1-P lyase) was strongly activated, while expression of the SGPP2 (SPH-1-P phosphatase) gene was reduced. Elucidation of mechanisms for the regulation of sphingolipid metabolism in ALS will help to identify molecular targets for the new-generation drugs.

Regression algorithm for calculating second-dimension retention indices in comprehensive two-dimensional gas chromatography.

Gas chromatography-mass spectrometry (GC-MS) is one of the most accurate, well developed, and reliable analytical tools for the analysis of volatile and semivolatile compounds. The GC-MS data have been extensively improved by enhancing the separation capacity via comprehensive two-dimensional gas chromatography (GC × GC). The reliability of the identification of the analytes in GC × GC-MS can be notably improved by applying the second-dimension retention index (2I) as additional analytical parameter along with the commonly used first dimension retention index (1I) and mass spectrum. A novel approach for calculating second-dimension retention indices (2I) for semivolatile organic compounds is proposed. It is noteworthy that the standards used in calculations are the same compounds recommended as internal standards by US EPA 8270 Method for analysis of semivolatile organic compounds. The new algorithm takes into account the analyte retention time and its retention temperature at the secondary column, (2tR) and (2TR), respectively. The experimental data collected with different primary oven temperature ramp rates and carrier gas flow rates have shown that the calculated by the proposed approach 2I values remain the same for each evaluated compound, drifting in a very narrow range. The proposed approach was tested using 100 organic compounds from various chemical classes including alkanes, phenols, nitrobenzenes, chlorinated hydrocarbons, anilines, polycyclic aromatic hydrocarbons (PAHs), phthalates, etc. The important advantage of the proposed 2I values for compounds of the same chemical origin (reference standards and analytes) involves applicability of well-known Lee's indices for non-polar phases. Therefore, the proposed approach can be used in targeted and non-targeted analysis of a wide range of organic compounds. The reduced version of the second dimension retention indices provides a valuable mapping of the homologues series of organic compounds, making their detection and identification easy and reliable.

Detection of semi-volatile compounds in cloud waters by GC×GC-TOF-MS. Evidence of phenols and phthalates as priority pollutants.

Although organic species are transported and efficiently transformed in clouds, more than 60% of this organic matter remains unspeciated. Using GCxGC-HRMS technique we were able to detect and identify over 100 semi-volatile compounds in 3 cloud samples collected at the PUY station (puy de Dôme mountain, France) while they were present at low concentrations in a very small sample volume (<25 mL of cloud water). The vast majority (∼90%) of the detected compounds was oxygenated, while the absence of halogenated organic compounds should be specially mentioned. This could reflect both the oxidation processes in the atmosphere (gas and water phase) but also the need of the compounds to be soluble enough to be transferred and dissolved in the cloud droplets. Furans, esters, ketones, amides and pyridines represent the major classes of compounds demonstrating a large variety of potential pollutants. Beside these compounds, priority pollutants from the US EPA list were identified and quantified. We found phenols (phenol, benzyl alcohol, p-cresole, 4-ethylphenol, 3,4-dimethylphenol, 4-nitrophenol) and dialkylphthalates (dimethylphthalate, diethylphthalate, di-n-butylphthalate, bis-(2-ethylhexyl)-phthalate, butylbenzylphthalate, di-n-octyl phthalate). In general, the concentrations of phthalates (from 0.09 to 52 µg L-1) were much higher than those of phenols (from 0.03 to 0.74 µg L-1). To our knowledge phthalates in clouds are described here for the first time. We investigated the variability of phenols and phthalates concentrations with cloud air mass origins (marine vs continental) and seasons (winter vs summer). Although both factors seem to have an influence, it is difficult to deduce general trends; further work should be conducted on large series of cloud samples collected in different geographic areas and at different seasons.

Semi volatile organic compounds in the snow of Russian Arctic islands: Archipelago Novaya Zemlya.

Environmental contamination of the Arctic has widely been used as a worldwide pollution marker. Various classes of organic pollutants such as pesticides, personal care products, PAHs, flame retardants, biomass burning markers, and many others emerging contaminants have been regularly detected in Arctic samples. Although numerous papers have been published reporting data from the Canadian, Danish, and Norwegian Arctic regions, the environmental situation in Russian Arctic remains mostly underreported. Snow analysis is known to be used for monitoring air pollution in the regions with cold climate in both short-term and long-term studies. This paper presents the results of a nontargeted study on the semivolatile organic compounds detected and identified in snow samples collected at the Russian Artic Archipelago Novaya Zemlya in June 2016. Gas chromatography coupled to a high-resolution time-of-flight mass spectrometer enabled the simultaneous detection and quantification of a variety of pollutants including those from the US Environmental Protection Agency (EPA) priority pollutants list, emerging contaminants (plasticizers, flame retardants-only detection), as well as the identification of novel Arctic organic pollutants, (e.g., fatty acid amides and polyoxyalkanes). The possible sources of these novel pollutants are also discussed. GC-HRMS enabled the detection and identification of emerging contaminants and novel organic pollutants in the Arctic, e.g., fatty amides and polyoxyalkanes.

Identification and interconversion of isomeric 4,5-functionalized 1,2,3-thiadiazoles and 1,2,3-triazoles in conditions of electrospray ionization.

1,2,3-Triazoles and 1,2,3-thiadiazoles have been receiving permanent interest due to their exciting chemical reactivity and interesting biological properties including antibacterial, anticancer and antiviral activities. There are four compounds bearing 1H-1,2,3-triazole core in clinical studies which may appear in the market of drugs in nearest future. Definitely reliable methods of their identification and quantification should be developed by that time. Mass spectrometry showed itself as the most reliable method of analysis when dealing with trace levels of organic compounds in the mixtures and in the most complex matrices, including biological ones. In the present study tandem mass spectrometry was used to study fragmentation pathways of protonated and deprotonated molecules of isomeric 4,5-functionalized 1,2,3-thiadiazoles and 1,2,3-triazoles in conditions of electrospray ionization (ESI). A group of marker ions allowing differentiation between the targeted isomeric compounds was established. Besides, interconversion of these isomers into one another was studied in the gas phase in conditions mimicking these processes in solution.

Molecular recognition of pseudodistamine isomeric precursors trans-3(4)-aminopiperidin-4(3)-ols by EI mass spectrometry.

Synthesis of drugs, biologically active compounds or their derivatives always requires precise and reliable method of their identification, including differentiation of the possible isomers. Pseudodistamines and their precursors became a matter of elevated attention due to their different enzymatic inhibition. This paper deals with one of the groups of the pseudodistamine precursors - trans-3(4)-aminopiperidin-4(3)-ols. Their synthesis brings to a mixture of 2 regioisomers, resulting in the necessity of their reliable recognition. NMR spectroscopy commonly used by organic chemists requires advance knowledge and experience to analyse the spectra of these regioisomers. Therefore, we herein proposed a simpler way to recognize trans-3(4)-aminopiperidin-4(3)-ols using mass spectrometry with electron ionization. Fragmentation of 4 pairs of aminopiperidinol regioisomers with variation of amine moiety was studied. The obtained results allowed defining a group of 3 ions ([M-18]+., [M-19]+, [M-43]+) related only to the structure of trans-4-aminopiperidin-3-ols and 1 ion (m/z 100) related to the structure of trans-3-aminopiperidin-4-ols. Besides, interrogation of intensity of ions common for spectra of both regioisomers allows making differentiation as well.

Novel pollutants in the Moscow atmosphere in winter period: Gas chromatography-high resolution time-of-flight mass spectrometry study.

The most common mass spectrometry approach analyzing contamination of the environment deals with targeted analysis, i.e. detection and quantification of the selected (priority) pollutants. However non-targeted analysis is becoming more often the method of choice for environmental chemists. It involves implementation of modern analytical instrumentation allowing for comprehensive detection and identification of the wide variety of compounds of the environmental interest present in the sample, such as pharmaceuticals and their metabolites, musks, nanomaterials, perfluorinated compounds, hormones, disinfection by-products, flame retardants, personal care products, and many others emerging contaminants. The paper presents the results of detection and identification of previously unreported organic compounds in snow samples collected in Moscow in March 2016. The snow analysis allows evaluation of long-term air pollution in the winter period. Gas chromatography coupled to a high resolution time-of-flight mass spectrometer has enabled us with capability to detect and identify such novel analytes as iodinated compounds, polychlorinated anisoles and even Ni-containing organic complex, which are unexpected in environmental samples. Some considerations concerning the possible sources of origin of these compounds in the environment are discussed.

Cyclization of N-arylcyclopropanecarboxamides into N-arylpyrrolidin-2-ones under electron ionization and in the condensed phase.

RATIONALE: Mass spectrometry is known as an excellent method to predict the behavior of organic compounds in solution. The behavior of organic compounds in the gas phase inside the ion source of a mass spectrometer allows their intrinsic properties to be defined, avoiding the influence of intermolecular interactions, counter ions and solvent effects. METHODS: Arylpyrrolidin-2-ones were obtained by condensed-phase synthesis from the corresponding N-arylcyclopropanecarboxamides. Electron ionization (EI) with accurate mass measurements by high-resolution time-of-flight mass-spectrometry and quantum chemical calculations were used to understand the behavior of the molecular radical cations of N-arylcyclopropanecarboxamides and N-arylpyrrolidin-2-ones in the ion source of a mass spectrometer. The geometries of the molecules, transition states, and intermediates were fully optimized using DFT-PBE calculations. RESULTS: Fragmentation schemes, ion structures, and possible mechanisms of primary isomerisation were proposed for isomeric N-arylcyclopropanecarboxamides and N-arylpyrrolidin-2-ones. Based on the fragmentation pattern of the N-arylcyclopropanecarboxamides, isomerisation of the original M+• ions into the M+• ions of the N-arylpyrrolidin-2-ones was shown to be only a minor process. In contrast, this cyclization proceeds easily in the condensed phase in the presence of Brønsted acids. CONCLUSIONS: Based on the experimental data and quantum chemical calculations the principal mechanism of decomposition of the molecular ions of N-arylcyclopropanecarboxamides involves their direct fragmentation without any rearrangements. An alternative mechanism is responsible for the isomerisation of a small portion of the higher energy molecular ions into the corresponding N-arylpyrrolidin-2-one ions. Copyright © 2016 John Wiley & Sons, Ltd.

Hydrophilic interaction liquid chromatography-tandem mass spectrometry methylphosponic and alkyl methylphosphonic acids determination in environmental samples after pre-column derivatization with p-bromophenacyl bromide.

Once exposed to the environment organophosphate nerve agents readily degrade by rapid hydrolysis to the corresponding alkyl methylphosphonic acids which do not exist in nature. These alkyl methylphosphonic acids are finally slowly hydrolyzed to methylphosphonic acid. Methylphosphonic acid is the most stable hydrolysis product of organophosphate nerve agents, persisting in environment for a long time. A highly sensitive method of methylphosphonic acid and alkyl methylphosphonic acids detection in dust and ground mixed samples has been developed and validated. The fact that alkyl methylphosphonic acids unlike methylphosphonic acid did not react with p-bromophenacyl bromide under chosen conditions was discovered. This allowed simultaneous chromatographic separation and mass spectrometric detection of derivatized methylphosphonic acid and underivatized alkyl methylphosphonic acids using HILIC-MS/MS method. Very simple sample pretreatment with high recoveries for each analyte was developed. Methylphosphonic acid pre-column derivate and alkyl methylphosphonic acids were detected using tandem mass spectrometry with electrospray ionization after hydrophilic interaction liquid chromatography separation. The developed approach allows achieving ultra-low detection limits: 200 pg mL(-1) for methylphosphonic acid, 70 pg mL(-1) for ethyl methylphosphonic acid, 8 pg mL(-1) for i-propyl methylphosphonic acid, 8 pg mL(-1) for i-butyl methylphosphonic acid, 5 pg mL(-1) for pinacolyl methylphosphonic acid in the extracts of dust and ground mixed samples. This approach was successfully applied to the dust and ground mixed samples from decommissioned plant for the production of chemical weapons.

[Applicability of MALDI Mass Spectrometry for Diagnostics of Phase Variants in Bacterial Populations].

Efficiency of MALDI mass spectrometry for differentiation between phenotypic phase variants (in colony morphology and virulence/avirulence) was investigated.for saprotrophic and opportunistically pathogenic bacteria of five genera (Acinetobacter, Arthrobacter, Rhodococcus, Corynebacterium, and Escherichia). Analysis of MALDI spectra (on the SA and HCCA matrices) included: (1) determination of similarity of the protein spectra as a percentage of the common protein peaks to the total amount of proteins, which reflects the phylogenetic relationships of the objects and has been recommended for identification of closely related species; (2) comparison of intensities of the common peaks; and (3) the presence of specific peaks as determinative characteristics of the variants. Under the standard analytical conditions the similarity between the MALDI profiles was shown to increase in the row: genus-species-strain-variant. Assessment of intensities of the common peaks was most applicable for differentiation between phase variants, especially in the case of high similarity of their profiles. Phase variants (A. oxydans strain K14) with similar colony morphotypes (S, R, M, and S(m)) grown on different media (LB agar, TSA, and TGYg) exhibited differences in their protein profiles reflecting the differences in their physiological characteristics. This finding is in agreement with our previous results on screening of the R. opacus with similar colony morphology and different substrate specificity in decomposition of chlorinated phenols. Analysis of MALDI spectra is probably the only efficient method for detection of such variants.

LC/MS study of the UV filter hexyl 2-[4-(diethylamino)-2-hydroxybenzoyl]-benzoate (DHHB) aquatic chlorination with sodium hypochlorite.

The fate of modern personal care products in the environment is becoming a matter of increasing concern because of the growing production and assortment of these compounds. More and more chemicals of this class are treated as emerging contaminants. Transformation of commercially available products in the environment may result in the formation of a wide array of their metabolites. Personal care products in swimming pools and in drinking water reservoirs may undergo oxidation or chlorination. There is much data on the formation of more toxic metabolites from original low toxicity commercial products. Therefore, reliable identification of all possible transformation products and a thorough study of their physicochemical and biological properties are of high priority. The present study deals with the identification of the products of the aquatic chlorination of the hexyl 2-[4-(diethylamino)-2-hydroxybenzoyl]-benzoate ultraviolet filter. High-performance liquid chromatography/mass spectrometry (HPLC/MS) and HPLC/MS/MS with accurate mass measurements were used for this purpose. As a result, three chlorinated transformation products were identified.

Composition and antimicrobial activity of the skin peptidome of Russian brown frog Rana temporaria.

A nano-HPLC-ESI-OrbiTrap study involving HCD and ETD spectra has been carried out to clarify the composition of the skin peptidome of brown Russian frogs Rana temporaria. This approach allowed determinantion of 76 individual peptides, increasing 3-fold the identified portion of the peptidome in comparison to that obtained earlier with FTICR MS. A search for the new bradykinin related peptides (BRPs) was carried out by reconstructing mass chromatograms based on the ion current of characteristic b- and y-ions. Several peptides were reported in the secretion of R. temporaria for the first time. The overall antibacterial activity of the skin secretion in general and of one individual peptide (Brevinin 1Tb) was determined using PMEU Spectrion (Portable Microbe Enrichment Unit) technology. The inhibitory effects of these peptides on Staphylococcus aureus and Salmonella enterica Serovar typhimutium were equal in scale to that reported for some antibiotics.