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Chengli Zu Herbert N. Praay Bruce M. Bell O. David Redwine 《Rapid communications in mass spectrometry : RCM》2010,24(1):120-128
A derivatization procedure has been developed for the improved characterization of fatty alcohol ethoxylate non‐ionic surfactants by liquid chromatography/mass spectrometry. The end hydroxyl group of each surfactant species was converted into an oxycarbonylbenzene‐2‐sulfonic acid group with 2‐sulfobenzoic anhydride under mild conditions. The produced sulfonic acid group allows all species, including fatty alcohols and those with less than three ethoxylates, to be uniformly ionized by electrospray ionization (ESI) mass spectrometry. Both acid and base can be used as a mobile phase additive for liquid chromatography without affecting Mn and average ethoxylate values, although ion intensities are suppressed during the ESI process. The method was used to analyze seven commercial fatty alcohol ethoxylate non‐ionic surfactants, and the determined Mn and EO values were comparable with the results obtained by NMR. The relative ratio of different fatty alcohol based ethoxylates in a sample can also be determined using the summed mass spectral data. Copyright © 2009 The Dow Chemical Company 相似文献
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The content and the three dimensional distribution of impurities play an important role in the production process of high
purity rhenium powder (99.99% purity grade) and for its further use as alloying and coating agent in high temperature applications.
In this paper the characterization of raw Re granulate, Re powder, cleaned by heat treatment, Re coatings, produced by most
common preparation methods (PVD and VPS) and PM Re by means of SIMS is presented. The analysis of the three dimensional distribution
of trace elements is performed by 3D SIMS. The quantification of carbon, which was not possible with other analytical techniques
as a result of the high volatility of Re2O7 until now, has been carried out by SIMS depth profile analysis. It is discussed if internal standards, produced by introduction
of defined amounts of carbon soot to the Re powder lead to useful results. 相似文献
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Teixeira Lincoln C. Linden James C. Schroeder Herbert A. 《Applied biochemistry and biotechnology》2000,84(1-9):111-127
Previous work in our laboratories has demonstrated the effectiveness of peracetic acid for improving enzymatic digestibility
of lignocellulosic materials. The use of dilute alkali solutions as a pre-pretreatment prior to peracetic acid lignin oxidation
increased carbohydrate hydrolysis yields in a synergistic as opposed to additive manner. Deacetylation of xylan is easily
achieved using dilute alkali solutions under mild conditions. In this article, we evaluate the effectiveness of peracetic
acid combined with an alkaline pre-pretreatment through simulataneous saccharification and cofermentation (SSCF) of pretreated
hybrid poplar wood and sugar can ebagasse. Respective ethanol yields of 92.8 and 91.9% of theoretical are achieved using 6%
NaOH/15% peracetic acid-pretreated substrates and recombinant Zymomonas mobilis CP4/p ZB5. Reduction of acetyl groups of the lignocellulosic materials is demonstrated following alkaline pre-pretreatments.
Such processing may be helpful in reducing peracetic acid requirements. The influence of deacetylation is more significant
in combined pretreatments using lower peracetic acid loadings. 相似文献