کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5162485 | 1379735 | 2011 | 12 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Characterization of humic substances by advanced solid state NMR spectroscopy: Demonstration of a systematic approach
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کلمات کلیدی
FSLGTPPMDEPTTOSSCP-MASHMQCHSQCnuclear magnetic resonance - رزونانس مغناطیسی هستهایChemical shift anisotropy - Anisotropy شبیه سازی شیمیاییHumic acid - اسید هیومیکdistortionless enhancement by polarization transfer - افزایش تحرک توسط انتقال قطبشheteronuclear multiple quantum coherence - انسجام کوانتومی چند گانه هسته ایCSA - ایالات مؤتلفهٔ آمریکاFourier transform infrared - تبدیل فوریه مادون قرمزNMR - تشدید مغناطیسی هستهای REDOR - دورRotational echo double resonance - رزونانس دو طرفه چرخشSuper - سوپرDipolar dephasing - ضایعات دیفرانسیلیFT-IR - طیف سنجی مادون قرمز تبدیل فوریهSPIDER - عنکبوتdirect polarization - قطبش مستقیمNatural organic matter - مواد آلی طبیعیNOM - نامHMBC یا Heteronuclear Multiple Bond Correlation - همبستگی پیوند چندگانه ناجورهستهheteronuclear multiple bond correlation - همبستگی چندگانه هترو هسته ایCross polarization - پلاریزه شدن صلیبheteronuclear single quantum coherence - یکپارچگی کوانتومی تک هسته ای
موضوعات مرتبط
مهندسی و علوم پایه
شیمی
شیمی آلی
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
Characterization of humic substances is challenging due to their structural complexity and heterogeneity. Solid state nuclear magnetic resonance (NMR) is regarded as one of the best tools for elucidating structures of humic substances. The primary solid state NMR technique that has been used so far is the routine 13C cross polarization-magic angle spinning (CP-MAS) technique. Although this technique has markedly advanced our understanding of humic substances, the full potential of NMR for characterizing humic substances has yet to be realized. Recent technical developments and applications of advanced solid state NMR have revealed the promise to provide deeper insights into structures of humic substances. In this paper, we summarized and demonstrated the systematic solid state NMR protocol for characterization of humic substances using a humic acid as an example. This protocol included (1) identification of specific functional groups using spectral editing techniques, occasionally assisted by 1H13C two-dimensional heteronuclear correlation (2D HETCOR) NMR, (2) quantification of specific functional groups based on direct polarization-magic angle spinning (DP-MAS) and DP-MAS with recoupled dipolar dephasing, combined with spectral editing techniques, (3) determination of connectivities and proximities of specific functional groups by 1H13C 2D HETCOR or 2D HETCOR combined with spectral editing techniques, and (4) examination of domains and heterogeneities by 1H13C 2D HETCOR with 1H spin diffusion. We used a soil humic acid as an example to demonstrate how this protocol was applied to the characterization of humic substances step by step. Afterwards, based on typical 13C NMR spectra of humic substances we described how we could combine different NMR techniques to identify specific functional groups band by band from downfield to upfield. Finally, we briefly mentioned the potential new NMR techniques that could be developed to enrich the current systematic protocol. This systematic protocol is not only applicable to humic substances but also to other natural organic matter samples.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Organic Geochemistry - Volume 42, Issue 8, September 2011, Pages 891-902
Journal: Organic Geochemistry - Volume 42, Issue 8, September 2011, Pages 891-902
نویسندگان
Jingdong Mao, Na Chen, Xiaoyan Cao,