New Oligomeric Dihydrochalcones in the Moss Polytrichum commune: Identification, Isolation, and Antioxidant Activity

One of the most widespread representatives of mosses in the temperate and boreal latitudes of the Northern Hemisphere is common haircap (Polytrichum commune), which is known as the largest moss in the world and widely used in traditional herbal medicine. Polyphenolic compounds constitute one of the most important groups of biologically active secondary metabolites of P. commune, however, the available information on their chemical composition is still incomplete and contradictory. In the present study, a group of dihydrochalcone polyphenolic derivatives that were not previously found in mosses was isolated from P. commune biomass using pressurized liquid extraction with aqueous acetone. The combination of two-dimensional NMR spectroscopy and high-performance liquid chromatography–high-resolution mass spectrometry allowed for identifying them as 3-hydroxyphloretin oligomers formed through a carbon–carbon bond between phloroglucinol and pyrocatechol moieties (“head-to-tail” coupling), with a polymerization degree of 2–5. The individual compounds isolated by preparative reverse-phase HPLC had a purity of 71 to 97% and demonstrated high radical scavenging activity (17.5–42.5% with respect to Trolox) determined by the photochemiluminescence method. Along with the low toxicity predicted by QSAR/QSTR algorithms, this makes 3-hydroxyphloretin oligomers a promising source for the production of biologically active food additives and pharmaceuticals

Suspect Screening and Semi-Quantification of Macrolide Antibiotics in Municipal Wastewater by High-Performance Liquid Chromatography—Precursor Ion Scan Tandem Mass Spectrometry

Macrolides are widely used in medicine and veterinary medicine, and are the leading antibiotics in terms of consumption. The release of macrolides and their metabolites into the environment through municipal wastewater can have an adverse effect on aquatic ecosystems and human health. In the present study, a method for the non-targeted screening and semi-quantitative determination of macrolide antibiotics and their derivatives in wastewater based on a combination of chromatographic separation and tandem mass spectrometric detection in precursor ion scan (PrecIS) mode has been proposed. Product ions with m/z 158 and 174 related to specific desosamine fragments were used as diagnostic ions for the PrecIS detection of the macrolide structures without (14- and 15-membered macrocycles) and with a (16-membered macrocycle) glycosylated desosamine moiety, respectively. The combination of the optimized solid phase extraction procedure and HPLC-MS/MS analysis in PrecIS mode allowed for the suspect screening of macrolides in municipal wastewater with limits of detection in the range of 4–150 ng L−1. The developed approach made it possible to detect and tentatively identify in municipal wastewater 17 compounds belonging to the macrolide class, including azithromycin, clarithromycin, josamycin and 14 metabolites with a total concentration of 1450 ng L−1

Rapid Simultaneous Quantification of 1-Formyl-2,2-Dimethylhydrazine and Dimethylurea Isomers in Environmental Samples by Supercritical Fluid Chromatography–Tandem Mass Spectrometry

When released to the environment, the rocket fuel unsymmetrical dimethylhydrazine (UDMH) undergoes oxidative transformations, resulting in the formation of an extremely large number of nitrogen-containing transformation products, including isomeric compounds which are difficult to discriminate by common chromatography techniques. In the present work, supercritical fluid chromatography–tandem mass spectrometry (SFC-MS/MS) was proposed for resolving the problem of fast separation and simultaneous quantification of 1-formyl-2,2-dimethylhydrazine (FADMH) as one of the major UDMH transformation products, and its isomers—1,1-dimethylurea (UDMU) and 1,2-dimethylurea (SDMU). 2-Ethylpyridine stationary phase provided baseline separation of analytes in 1.5 min without the distortion of the chromatographic peaks. Optimization of SFC separation and MS/MS detection conditions allowed for the development of rapid, sensitive, and “green” method for the simultaneous determination of FADMH, UDMU, and SDMU in environmental samples with LOQs of 1–10 µg L−1 and linear range covering three orders of magnitude. The method was validated and successfully tested on the real extracts of peaty and sandy soils polluted with rocket fuel and UDMH oxidation products. It was shown that both UDMU and SDMU are formed in noticeable amounts during UDMH oxidation. Despite relatively low toxicity, UDMU can be considered one of the major UDMH transformation products and a potential marker of soil pollution with toxic rocket fuel

Comprehensive Characterization of Chemical Composition and Antioxidant Activity of Lignan-Rich Coniferous Knotwood Extractives

A knotwood of coniferous trees containing large amounts of polyphenolic extractives is considered a promising industrial-scale source of lignans possessing antioxidant properties and other bioactivities. The present study is aimed at a detailed characterization of the chemical composition and antioxidant activity of lignan-rich extractives obtained from the knotwood of the Norway spruce, Scotch pine, Siberian fir, and Siberian larch growing in the European North of Russia as a region with a highly developed forest industry. To achieve this, a comprehensive approach based on a combination of two-dimensional NMR spectroscopy with high-performance liquid chromatography—high-resolution Orbitrap mass spectrometry, and the determination of antioxidant activity by the three complementary methods were proposed. The studied knotwood samples contained from 3.9 to 17% of extractive substances and were comparable to Trolox’s antioxidant activity in the single-electron transfer processes and superoxide radical scavenging, which is associated with the predominance of polyphenolic compounds. The latter was represented by 12 tentatively identified monolignans and 27 oligolignans containing 3–5 phenylpropane units in their structure. The extracts were characterized by an identical set of lignans and differed only in the ratios of their individual compounds. Other components of the knotwood were flavonoids taxifolin, quercetin (Siberian larch), and three stilbenes (pinosylvin, its methyl ester, and pterostilbene), which were identified in the Scotch pine extractives. Sesquiterpene juvabione and its derivatives were found in extracts of Siberian larch knotwood

Determination of Pentacyclic Triterpenoids in Plant Biomass by Porous Graphitic Carbon Liquid Chromatography—Tandem Mass Spectrometry

Pentacyclic triterpenoids (PCTs), which possess a number of bioactive properties, are considered one of the most important classes of secondary plant metabolites. Their chromatographic determination in plant biomass is complicated by the need to separate a large number of structurally similar compounds belonging to several classes that differ greatly in polarity (monools, diols, and triterpenic acids). This study proposes a rapid, sensitive, and low-cost method for the simultaneous quantification of ten PCTs (3β-taraxerol, lupeol, β-amyrin, α-amyrin, betulin, erythrodiol, uvaol, betulinic, oleanolic, and ursolic acids) by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) using porous graphitic carbon (Hypercarb) as a stationary phase capable of hydrophobic retention and specific interactions with analytes. Revealing the effects of the mobile phase composition, pH, ionic strength, and column temperature on retention and selection of chromatographic conditions on this basis allowed for the effective separation of all target analytes within 8 min in gradient elution mode and attaining limits of detection in the range of 4–104 µg L−1. The developed method was fully validated and successfully tested in the determination of PCTs in common haircap (Polytrichum commune) and prairie sphagnum (Sphagnum palustre) mosses, and fireweed (Chamaenerion angustifolium) stems and leaves

Supercritical Fluid Chromatography—Tandem Mass Spectrometry for Rapid Quantification of Pentacyclic Triterpenoids in Plant Extracts

Pentacyclic triterpenoids (PCTs) are a widely distributed class of plant secondary metabolites. These compounds have high bioactive properties, primarily antitumor and antioxidant activity. In this study, a method was developed for the quantitative analysis of pentacyclic triterpenoids in plants using supercritical fluid chromatography–tandem mass spectrometry (SFC-MS/MS). Separation of ten major PCTs (friedelin, lupeol, β-amyrin, α-amyrin, betulin, erythrodiol, uvaol, betulinic, oleanolic and ursolic acids) was studied on six silica-based reversed stationary phases. The best results (7 min analysis time in isocratic elution mode) were achieved on an HSS C18 SB stationary phase using carbon dioxide—isopropanol (8%) mobile phase providing decisive contribution of polar interactions to the retention of analytes. It was shown that the use of atmospheric pressure chemical ionization (APCI) is preferred over atmospheric pressure photoionization (APPI). The combination of SFC with APCI-MS/MS mass spectrometry made it possible to achieve the limits of quantification in plant extracts in the range of 2.3–20 μg·L−1. The developed method was validated and tested in the analyses of birch outer layer (Betula pendula) bark, and licorice (Glycyrrhiza glabra) root, as well as lingonberry (Vaccinium vitis-idaea), cranberry (Vaccinium oxycoccos), apple (Malus domestica “Golden Delicious” and Malus domestica “Red Delicious”) peels

Occurrence of Volatile and Semi-Volatile Organic Pollutants in the Russian Arctic Atmosphere: The International Siberian Shelf Study Expedition (ISSS-2020)

Environmental issues in the Arctic region are of primary importance due to the fragility of the Arctic ecosystem. Mainly persistent organic compounds are monitored in the region by nine stationary laboratories. Information on the volatile (VOC) and semi volatile (SVOC) organic priority pollutants is very limited, especially for the Russian Arctic. Air samples from 16 sites along the Russian Arctic coast from the White Sea to the East Siberian Sea were collected on sorption tubes packed with Tenax, Carbograph, and Carboxen sorbents with different selectivity for a wide range of VOCs and SVOCs in 2020 within the framework of the International Siberian Shelf Study Expedition on the research vessel Akademik Keldysh. Thermal desorption gas chromatography–high-resolution mass spectrometry with Orbitrap was used for the analysis. Eighty-six VOCs and SVOCs were detected in the air samples at ng/m3 levels. The number of quantified compounds varied from 26 to 66 per sample. Benzoic acid was the major constituent, followed by BTEX, phenol, chloroform, bis(2-ethylhexyl) phthalate, and carbon tetrachloride. The study allowed for obtaining the first ever data on the presence of 138 priority pollutants in the air of Russian Arctic, whereas the thorough assessment of their possible sources will be the aim of a next investigation

Direct determination of hydrazine, methylhydrazine, and 1,1-dimethylhydrazine by zwitterionic hydrophilic interaction liquid chromatography with amperometric detection

<p>A promising alternative to ion-chromatographic methods currently used for the direct determination of hydrazines is provided by hydrophilic interaction liquid chromatography (HILIC). In this work, we propose a method for the simultaneous determination of hydrazine, methylhydrazine and 1,1-dimethylhydrazine in natural waters and soils based on a combination of chromatographic separation on a zwitterionic sulfobetaine stationary phase (Nucleodur HILIC) in the HILIC mode with amperometric detection.</p> <p>Effects of different factors on the retention of analytes were studied and the optimum conditions of analysis were found. We recommend a mixture of acetonitrile with an aqueous phosphate buffer solution of pH 2.5 (78:22 v/v) with an ionic strength of 20 mM as a mobile phase. Detection in the direct current mode was performed at a working electrode potential of 1.1 V.</p> <p>The advantages of the method are the high efficiency of separation, rapidity, high sensitivity and a wide dynamic range of analyte concentrations, covering four orders of magnitude. The attained LOD values for analytes lie in the range 0.07–0.13 μg L^–1, which is two orders of magnitude lower than those in currently used methods of ion chromatography with electrochemical and mass spectrometric detection.</p> <p>The method was validated on samples of natural waters of different origin using the added–found technique. It was found that the error of analysis did not exceed 10% for river and ground waters and increased to 20–30% for peat bog surface waters.</p> <p>The possibility of application of the developed method to the analysis of soils was shown on samples of peat bog soils selected at places of impact of the first steps of carrier rockets and polluted by rocket fuel based on 1,1-dimethylhydrazine.</p