Approaches for the unambiguous identification of lipophilic arsenic species in Saccharina latissima (sugar kelp) have been studied. Parallel use of high resolution ICPMS and electrospray ionization ...(ESI)-MS after separation revealed that Saccharina latissima contained three distinct classes of lipophilic As-species, a family of arsenic containing phospholipids (AsPL), all including As in the form of As–sugar–PO4, As-containing hydrocarbons (AsHC), and As-containing polyunsaturated fatty acids (AsFA). For detailed identification, the use of phospholipases, in particular phospholipase A2, was essential to define the fatty acid composition (determination of regioisomers) of the lipids without purification of the sample, while fragmentation of the molecules by MS2 measurements alone did not supply this information. Some of the identified AsPL contained unsaturated fatty acids (C16:1, C18:1 to C18:3), but saturated fatty acids dominated the AsPL. The fatty acid bound to the position 2″ was predominantly C16:0. Complete lipid hydrolysis showed that this alga did not contain arsenic containing fatty acids (AsFA) bound to complex lipids. Our investigations indicate that in addition to RP-HPLC-ICPMS/ESI-MS a range of different derivatization methods should be used for the comprehensive identification of unknown lipid-soluble arsenic compounds.
Electrochemical oxidative degradation is one of the most promising methods for generation of phenolic fine chemicals from the renewable feedstock lignin. High selectivity, no reagent waste, as well ...as cost efficiency are major advantages of this particular process. Application of Ni‐ and Co‐based anode materials led to the best results in respect to product yield and selectivity. Interestingly, repeated use of Ni foam electrodes for electrochemical oxidative degradation resulted in significantly increased yields of vanillin, indicating a modification of the electrode surface. In particular, activation of the electrodes by electrochemical treatment of black liquor enabled an activation which further increased the electrocatalytic activity as well as the yield of the aroma chemical vanillin up to more than 100 % compared to non‐activated Ni foam electrodes. Additionally, this activated electrode surface was analyzed via flowing atmospheric pressure afterglow surface desorption mass spectrometry (FAPA‐MS). The measurement revealed diaminotoluene as a major compound in this adsorption layer, which indicates that this compound is partly responsible for the activation process. Most likely, electrochemical induced deposition of such an organic surface layer enhances the lipophilicity of the electrode surface and increases the accessibility of relevant structural features of lignin particles to the anodic surface, resulting in a higher yield of the desired degradation product vanillin.
Selective electrochemical degradation of Kraft lignin to vanillin: through the use of different transition metal‐based alloys and performance‐enhanced anodes a selective electrochemical depolymerization of lignin is realized. Additionally, in black liquor activated nickel foam electrodes are investigated, which show an outstanding performance for selective electrochemical lignin degradation.
Peroxy acids were
recently found to be involved in new particle formation in the atmosphere and could also substantially
contribute towards particle toxicity. However, a lack of suitable analytical
...methods for the detection and characterisation of peroxy acids in the
particle phase is currently hindering the quantitative investigation of their
contribution to these important atmospheric processes. Further development of
appropriate techniques and relevant standards is therefore urgently needed.
In this study, we synthesised three peroxypinic acids, developed a liquid
chromatography separation method and characterised them with tandem mass
spectrometry. The observed fragmentation patterns clearly distinguish the
different peroxypinic acids from both the acid and each other, showing
several neutral losses previously already observed for other peroxy acids.
Both monoperoxypinic acids were found to be present in secondary organic
aerosol generated from ozonolysis of α-pinene in laboratory
experiments. The yield of monoperoxypinic acid formation was not influenced
by humidity. Monoperoxypinic acid quickly degrades on the filter, with about
60 % lost within the first 5 h. This fast degradation shows that time
delays in traditional off-line analysis will likely lead to severe
underestimates of peroxy compound concentrations in ambient particles.
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