A targeted GC-MS/MS approach for the determination of eight sterols in microgreen and mature plant material.

Over the past decades, a remarkable number of scientific studies supported the correlation between an adequate dietary intake of phytosterols (PS) and the reduced risk of cardiovascular diseases. PS are known to inhibit the intestinal absorption of cholesterol, thus promoting the reduction of the low-density lipoproteins (LDL) amount in the bloodstream. Despite the fact that a non-negligible atherogenicity was recognized to PS, thus requiring a careful risk-benefits assessment for plant sterol supplementation, the potential role of PS as cholesterol-lowering agents has been contributing to the spreading awareness of the health benefits associated with the consumption of plant-based foods. In recent years, this has been fueling the market of innovative vegetable products, such as microgreens. Surprisingly, the recent literature concerning microgreens exhibited the lack of studies focusing on the characterization of PS. To fill this gap, a validated analytical method based on the hyphenation of gas chromatography and tandem mass spectrometry is proposed here for the quantitative analysis of eight phytosterols, namely ß-sitosterol, campesterol, stigmasterol, brassicasterol, isofucosterol, and cholesterol, lathosterol and lanosterol. The method was exploited for the characterization of the PS content in 10 microgreen crops, i.e., chia, flax, soybean, sunflower, rapeseed, garden cress, catalogna chicory, endive, kale and broccoli raab. Finally, these results were compared to the PS content of mature forms of kale and broccoli raab. A remarkable amount of PS was detected in chia, flax, rapeseed, garden cress, kale, and broccoli raab microgreens. 100 g (wet weight) of these microgreen crops were found to contain from 20 to 30 mg of the investigated PS. Interestingly, in the case of kale and broccoli raab microgreens, the overall PS content was higher than the one measured in the edible parts of the corresponding mature forms. Additionally, a symmetric change of the PS inner profile was observed between the two growth stages of the latter two crops. Here, the overall decrease of the PS sterol content in the mature forms was associated with the increase of the relative amount of ß-sitosterol and campesterol at the expense of minor PS species, such as brassicasterol.

Surface chemistry of 2,3-dibromosubstituted norbornadiene/quadricyclane as molecular solar thermal energy storage system on Ni(111).

Dwindling fossil fuels force humanity to search for new energy production routes. Besides energy generation, its storage is a crucial aspect. One promising approach is to store energy from the sun chemically in strained organic molecules, so-called molecular solar thermal (MOST) systems, which can release the stored energy catalytically. A prototypical MOST system is norbornadiene/quadricyclane (NBD/QC) whose energy release and surface chemistry need to be understood. Besides important key parameters such as molecular weight, endergonic reaction profiles, and sufficient quantum yields, the position of the absorption onset of NBD is crucial to cover preferably a large range of sunlight's spectrum. For this purpose, one typically derivatizes NBD with electron-donating and/or electron-accepting substituents. To keep the model system simple enough to be investigated with photoemission techniques, we introduced bromine atoms at the 2,3-position of both compounds. We study the adsorption behavior, energy release, and surface chemistry on Ni(111) using high-resolution X-ray photoelectron spectroscopy (HR-XPS), UV photoelectron spectroscopy, and density functional theory calculations. Both Br2-NBD and Br2-QC partially dissociate on the surface at ∼120 K, with Br2-QC being more stable. Several stable adsorption geometries for intact and dissociated species were calculated, and the most stable structures are determined for both molecules. By temperature-programmed HR-XPS, we were able to observe the conversion of Br2-QC to Br2-NBD in situ at 170 K. The decomposition of Br2-NBD starts at 190 K when C-Br bond cleavage occurs and benzene and methylidene are formed. For Br2-QC, the cleavage already occurs at 130 K when cycloreversion to Br2-NBD sets in.

Mildly oxidized HDL decrease agonist-induced platelet aggregation and release of pro-coagulant platelet extracellular vesicles.

Stored platelet concentrates (PLCs) for therapeutic purpose, develop a platelet storage lesion (PSL), characterized by impaired platelet (PLT) viability and function, platelet extracellular vesicle (PL-EV) release and profound lipidomic changes. Whereas oxidized low-density lipoprotein (oxLDL) activates PLTs and promotes atherosclerosis, effects linked to oxidized high-density lipoprotein (oxHDL) are poorly characterized. PLCs from blood donors were treated with native (nHDL) or mildly oxidized HDL (moxHDL) for 5days under blood banking conditions. Flow cytometry, nanoparticle tracking analysis (NTA), aggregometry, immunoblot analysis and mass spectrometry were carried out to analyze PL-EV and platelet exosomes (PL-EX) release, PLT aggregation, protein expression, and PLT and plasma lipid composition. In comparison to total nHDL, moxHDL significantly decreased PL-EV release by -36% after 5days of PLT storage and partially reversed agonist-induced PLT aggregation. PL-EV release positively correlated with PLT aggregation. MoxHDL improved PLT membrane lipid homeostasis through enhanced uptake of lysophospholipids and their remodeling to corresponding phospholipid species. This also appeared for sphingomyelin (SM) and d18:0/d18:1 sphingosine-1-phosphate (S1P) at the expense of ceramide (Cer) and hexosylceramide (HexCer) leading to reduced Cer/S1P ratio as PLT-viability indicator. This membrane remodeling was associated with increased content of CD36 and maturation of scavenger receptor-B1 (SR-B1) protein in secreted PL-EVs. MoxHDL, more potently than nHDL, improves PLT-membrane lipid homeostasis, partially antagonizes PL-EV release and agonist-induced PLT aggregation. Altogether, this may be the result of more efficient phospho- and sphingolipid remodeling mediated by CD36 and SR-B1 in the absence of ABCA1 on PLTs. As in vitro supplement in PLCs, moxHDL has the potential to improve PLC quality and to prolong storage.

Potential of gas chromatography-atmospheric pressure chemical ionization-time-of-flight mass spectrometry for the determination of sterols in human plasma.

The application of Gas Chromatography (GC)-Atmospheric Pressure Chemical Ionization (APCI)-Time-of-Flight Mass Spectrometry (TOF-MS) is presented for sterol analysis in human plasma. A commercial APCI interface was modified to ensure a well-defined humidity which is essential for controlled ionization. In the first step, optimization regarding flow rates of auxiliary gases was performed by using a mixture of model analytes. Secondly, the qualitative and quantitative analysis of sterols including oxysterols, cholesterol precursors, and plant sterols as trimethylsilyl-derivatives was successfully carried out. The characteristics of APCI together with the very good mass accuracy of TOF-MS data enable the reliable identification of relevant sterols in complex matrices. Linear calibration lines and plausible results for healthy volunteers and patients could be obtained whereas all mass signals were extracted with an extraction width of 20 ppm from the full mass data set. One advantage of high mass accuracy can be seen in the fact that from one recorded run any search for m/z can be performed.

Gas chromatography-tandem mass spectrometry method for the simultaneous determination of oxysterols, plant sterols, and cholesterol precursors.

BACKGROUND: Cholesterol precursors and plant sterols have considerable potential as plasma biomarkers in several disorders of sterol metabolism and intestinal sterol absorption. Oxysterols are associated with atherogenesis, neurodegeneration, and inflammation. We developed a GC-MS method for the simultaneous analysis of these species in human plasma, including 24-, 25-, 27-hydroxycholesterol; 7-ketocholesterol; lanosterol; lathosterol; 7-dehydrocholesterol; desmosterol; stigmasterol; sitosterol; and campesterol. METHODS: Sterols were hydrolyzed with ethanolic potassium hydroxide solution, extracted by liquid/liquid extraction with n-hexane, and derivatized with N-methyl-N-trimethylsilyl-trifluoracetamide. Positive chemical ionization with ammonia, as reagent gas, was applied to generate high abundant precursor ions. RESULTS: The definition of highly sensitive precursor/product ion transitions, especially for coeluting substances, allowed fast gas chromatography run times of under 8.5 min. Using the multiple reaction monitoring mode, detection limits in the picogram per milliliter range could be achieved for most compounds. The method was validated for precision and recovery. Intraassay and interassay CVs were mostly <15% for serum and plasma samples. The recoveries of supplemented plasma samples in different concentrations were 88%-117%. The method was applied to stratification of patients with disorders in cholesterol biosynthesis and/or cholesterol absorption in hypercholesterolemia. The method revealed associations of sterol species with thyroid dysfunction and type 2 diabetes. CONCLUSIONS: This method allows high-throughput sterol profiling in various diseases.

Decreasing concentrations of volatile organic compounds (VOC) emitted following home renovations.

Volatile organic compounds (VOC) play an important role indoors since they have been linked to health symptoms and disorders. Particularly, after renovation activities, high indoor VOC concentrations have been observed. The study will give an indication, for the first time under real conditions, of the to-be-expected time frame for renovation-derived indoor pollution decreases when the exposure to it will reach a reference level. The decrease in the concentrations of investigated 26 VOC after renovations was assessed under real-life situations. Both the daily VOC concentration was measured by active sampling for 30 days in selected homes which had undergone various renovations and, as part of an epidemiologic study, the same VOC were collected monthly using passive samplers in 243 homes. An exponential function was used to interpret the concentration decay. The average time range which has to elapse following renovation activities before a guideline value or reference load is reached showed a time range between 2 and 8 weeks. This waiting time had at least be applicable to public buildings and institutions (especially relevant in case of nurseries, playschools etc.) with increasingly being implemented in private homes as well. Practical Implications After renovation an optimal waiting period had to be up to 60 days before the rooms will be used again. Fourteen days are possible, but increased ventilation is recommended. These had to be applicable at least for public buildings used by risk groups like young children. Renovations had to be carried out in summer season to ensure optimal ventilation to reduce the waiting time.

Sonoelectrochemical analysis of trace metals.

Ultrasonically-enhanced mass transport was exploited to increase preconcentration efficiency in anodic stripping voltammetry. We developed a Nafion-coated mercury thin-film working electrode which is stable under ultrasonic irradiation, making it possible to achieve very low limits of detection for relatively short preconcentration times. This allows the investigation of a variety of biological and environmental samples.

Nafion-coated mercury thin film electrodes for batch-injection analysis with anodic stripping voltammetry.

Batch-injection analysis exhibits the advantages of rapid and simple electroanalysis of microlitre samples. Nafion-coated mercury thin film electrodes have been evaluated for use in batch-injection analysis with anodic stripping voltammetry (BIA-ASV). The advantages of Nafion-coated electrodes in reducing electrode contamination by components of complex matrices are combined with the analysis of small microlitre sample volumes. The measurement of traces of lead and cadmium is used to illustrate the approach. An optimised procedure for formation of Nafion-coated mercury thin film electrodes is evolved. The relative sensitivity for BIA-ASV at electrodes with and without Nafion coatings is 0.9 and 0.8 for cadmium and lead respectively; detection limits are 2 x 10(-9) M and 4 x 10(-9) M. Studies were done concerning the influence of surfactants and their effect was found to be much less with the Nafion film coating. Applications to real environmental samples are demonstrated.