Urinary nuclear magnetic resonance spectroscopy of a Bangladeshi cohort with hepatitis-B hepatocellular carcinoma: A biomarker corroboration study

AIM: To establish if a distinct urinary metabolic profile could be identified in Bangladeshi hepatitis-B hepatocellular carcinoma (HCC) patients compared to cirrhosis patients and controls.METHODS: Urine samples from 42 Bangladeshi patients with HCC (39 patients with hepatitis-B HCC), 47 with cirrhosis on a background of hepatitis B, 46 with chronic hepatitis B, and seven ethnically-matched healthy controls were analyzed using nuclear magnetic resonance (NMR) spectroscopy. A full dietary and medication history was recorded for each subject. The urinary NMR data were analyzed using principal component analysis (PCA) and orthogonal partial least squared discriminant analysis (OPLS-DA) techniques. Differences in relative signal levels of the most discriminatory metabolites identified by PCA and OPLS-DA were compared between subject groups using an independent samples Kruskal-Wallis one-way analysis of variance (ANOVA) test with all pairwise multiple comparisons. Within the patient subgroups, the Mann-Whitney U test was used to compare metabolite levels depending on hepatitis B e-antigen (HBeAg) status and treatment with anti-viral therapy. A Benjamini-Hochberg adjustment was applied to acquire the level of significance for multiple testing, with a declared level of statistical significance of P < 0.05.RESULTS: There were significant differences in age (P < 0.001), weight (P < 0.001), and body mass index (P < 0.001) across the four clinical subgroups. Serum alanine aminotransferase (ALT) was significantly higher in the HCC group compared to controls (P < 0.001); serum α-fetoprotein was generally markedly elevated in HCC compared to controls; and serum creatinine levels were significantly reduced in the HCC group compared to the cirrhosis group (P = 0.004). A three-factor PCA scores plot showed clustering of the urinary NMR spectra from the four subgroups. Metabolites that contributed to the discrimination between the subgroups included acetate, creatine, creatinine, dimethyamine (DMA), formate, glycine, hippurate, and trimethylamine-N-oxide (TMAO). A comparison of relative metabolite levels confirmed that carnitine was significantly increased in HCC; and creatinine, hippurate, and TMAO were significantly reduced in HCC compared to the other subgroups. HBeAg negative patients showed a significant increase in creatinine (P = 0.001) compared to HBeAg positive patients in the chronic hepatitis B subgroup, whilst HBeAg negative patients showed a significant decrease in DMA (P = 0.004) in the cirrhosis subgroup compared to HBeAg positive patients. There were no differences in metabolite levels in HCC patients who did or did not receive antiviral treatment.CONCLUSION: Urinary NMR changes in Bangladeshi HCC were identified, corroborating previous findings from Egypt and West Africa. These findings could form the basis for the development of a cost-effective HCC dipstick screening test.

Body mass index and its effects on liver fat content in overweight and obese young adults by proton magnetic resonance spectroscopy technique

AIM To assess the association between liver fat content(LFC) and weight status in young adults using proton magnetic resonance spectroscopy(1H MRS) technique.METHODSSeventy-eight healthy young adults, between 19-30 years of age participated in this study. This group was then separated into a control of 39 subjects and an overweight/obese group(OW/OB group) consisting of 39 subjects. Blood biochemical quantity and 1 H MRS was performed for LFC assessment.RESULTS LFC was found to be almost three times higher in OW/OB group when compared to the control group. A 48.7% incidence of non-alcoholic fatty liver disease in the OW/OB group was found. Blood biochemical measurements showed statistically higher low-density lipoproteins and triglyceride, lower highdensity lipoproteins, and increased glycosylated hemoglobin and fasting glucose in the OW/OB group. Body mass index was a significant independent predictor for LFC after adjusting for age and sex(multiple linear regression; β = 0.459, P <0.001).CONCLUSION Due to the prevalence of high LFC in the OW/OB group, it can be proposed that weight gain and obesity are sensitive indicators of high hepatic fat content.

Using Nuclear Magnetic Resonance and MS/MS Spectroscopy for the Identification of Brodimoprim Metabolites in Rat Urine

Eight metabolites of brodimoprim (BDP) in rat urine were detected by NMR and ESIMS/MS. They were demethyl-BDP glucuronide, demethyl-BDP sulfurate, demethyl-BDP glucuronide sulfurate, alpha -hydroxyl-BDP, alpha -hydroxyl-BDP glucuronide, BDP sulfurate, N-oxide-BDP sulfurate, and alpha -hydroxyl-N-oxide-BDP sulfurate. All the sulfurates are reported for the first time.

Nuclear magnetic resonance spectroscopy is highly sensitive for lipid-soluble metabolites

Although the water-soluble metabolite profile of human mesenchymal stem cells is known, the lipid profile still needs further investigation. In this study, methanol-chloroform was used to extract lipid-soluble metabolites and perchloric acid was used to extract water-soluble metabolites. Fur- thermore, a dual phase extraction method using methanol-chloroform and water was used to obtain both water and lipid fractions simultaneously. All metabolite extractions were analyzed on a 9.4T high-resolution nuclear magnetic resonance spectrometer. Metabolite resonance peaks were as- signed in the acquired spectra according to the chemical shift, and the extraction efficiency of dif- ferent methods was compared. Results showed that in the spectra of water-soluble extracts, major metabolites comprised low molecular weight metabolites, including lactate, acetic acid, fatty acids, threonine, glutamic acid, creatine, choline and its derivatives, while in the spectra of lipid-soluble extracts, most metabolites were assigned to fatty acids. Among the different extraction procedures, perchloric acid was more efficient in extracting water-soluble metabolites and methanol-chloroform was efficient in extracting organic components compared with the dual phase extraction method. Nuclear magnetic resonance spectroscopy showed that as low as 0.7 mg organic yield was enough to obtain clear resonance peaks, while about 6.0 mg water-soluble yield was needed to obtain rela- tively favorable spectral lines. These results show that the efficiency of extracting water and lipid fractions is higher using perchloric acid and methanol-chloroform compared with dual phase ex- traction and that nuclear magnetic resonance spectroscopy is highly sensitive for analyzing lipid-soluble extracts.

Rapid and sensitive analysis of trace b-blockers by magnetic solidphase extraction coupled with Fourier transform ion cyclotron resonance mass spectrometry

A rapid and sensitive method for analyzing trace b-blockers in complex biological samples,which involved magnetic solid-phase extraction(MSPE)coupled with Fourier transform ion cyclotron resonance mass spectrometry(FTICR-MS),was developed.Novel nanosilver-functionalized magnetic nanoparticles with an interlayer of poly(3,4-dihydroxyphenylalanine)(polyDOPA@Ag-MNPs)were synthesized and used as MSPE adsorbents to extract trace b-blockers from biological samples.After extraction,the analytes loaded on the polyDOPA@Ag-MNPs were desorbed using an organic solvent and analyzed by FTICR-MS.The method was rapid and sensitive,with a total detection procedure of less than 10 min as well as limits of detection and quantification in the ranges of 3.5-6.8 pg/mL and 11.7-22.8 pg/mL,respectively.The accuracy of the method was also desirable,with recoveries ranging from 80.9%to 91.0%following the detection of analytes in human blood samples.All the experimental results demonstrated that the developed MSPE-FTICR-MS method was suitable for the rapid and sensitive analysis of trace b-blockers in complex biological samples.

Conformational Analysis of γ-Butyrolactones by Nuclear Magnetic Resonance Spectroscopy

A series of trans-4, 5-disubstituted -γ-butyrolactones are found to assume two different envelope conformations by means of nuclear magnetic resonance spectroscopy.

Crystallochemical Characterizations, Raman Spectroscopy and Studies Nuclear Magnetic Resonance (NMR) of Cu₂Zn(Sn, Si)S₄Compounds for Photovoltaic Applications

In this study, Si-doped Cu2ZnSnS4 compounds (Cu2ZnSn1-xSixS4, 0 ≤ x ≤ 1) were prepared by solid state reaction method for use of materials for photovoltaic cells. The structural and spectroscopic properties of the as-prepared compounds were studied by X-ray diffraction (XRD), 119Sn, 29Si and 65Cu Magic Angle Spinning nuclear magnetic resonance (MAS NMR) and Raman spectroscopy. The Si-substitution in the Sn-site induces three different types of XRD patterns which depend largely on the Si content in the compound. For 0 ≤ x ≤ 0.5, XRD analysis reveals the presence of a pure tetragonal phase of solid solution with I-42m as a space group. Mixed tetragonal and orthorhombic phases were observed for 0.5 < x < 0.8, followed by a pure orthorhombic structure with a space group Pmn21 at high content of Si (x ≥ 0.8). 119Sn MAS NMR spectra show the presence of Sn/Si disorder as a function of the Si content. The 65Cu MAS NMR spectra of the quadratic solid solution confirm the presence of the two copper sites (Cu-2a and Cu-2c) at 780 ppm while in the case of the orthorhombic solid solution samples, a very broad band is observed. The optical properties were investigated of all compounds by UV-Vis diffuse reflectance and the obtained optical band gap values (1.31 to 2.43 eV) confirm a semiconductor character.

7.0T nuclear magnetic resonance evaluation of the amyloid beta(1–40) animal model of Alzheimer's disease: comparison of cytology verification

3.0T magnetic resonance spectroscopic imaging brain function in Alzheimer＇s disease. However, is a commonly used method in the research ot the role of 7.0T high-field magnetic resonance spectroscopic imaging in brain function of Alzheimer＇s disease remains unclear. In this study, 7.0T magnetic resonance spectroscopy showed that in the hippocampus of Alzheimer＇s disease rats, the N-acetylaspartate wave crest was reduced, and the creatine and choline wave crest was elevated. This finding was further supported by hematoxylin-eosin staining, which showed a loss of hippocampal neurons and more glial cells. Moreover, electron microscopy showed neuronal shrinkage and mitochondrial rupture, and scanning electron microscopy revealed small size hippocampal synaptic vesicles, incomplete synaptic structure, and reduced number. Overall, the results revealed that 7.0T high-field nuclear magnetic resonance spectroscopy detected the lesions and functional changes in hippocampal neurons of Alzheimer＇s disease rats in vivo, allowing the possibility for assessing the success rate and grading of the amyloid beta （1-40） animal model of Alzheimer＇s disease.

Proton nuclear magnetic resonance-based metabonomic models for non-invasive diagnosis of liver fibrosis in chronic hepatitis C:Optimizing the classification of intermediate fibrosis

AIM To develop metabonomic models(MMs), using 1 H nuclear magnetic resonance(NMR) spectra of serum, to predict significant liver fibrosis(SF: Metavir ≥ F2), advanced liver fibrosis(AF: METAVIR ≥ F3) and cirrhosis(C: METAVIR = F4 or clinical cirrhosis) in chronic hepatitis C(CHC) patients. Additionally, to compare the accuracy of the MMs with the aspartate aminotransferase to platelet ratio index(APRI) and fibrosis index based on four factors(FIB-4). METHODS Sixty-nine patients who had undergone biopsy in the previous 12 mo or had clinical cirrhosis were included. The presence of any other liver disease was a criterion for exclusion. The MMs, constructed using partial least squares discriminant analysis and linear discriminant analysis formalisms, were tested by cross-validation, considering SF, AF and C. RESULTS Results showed that forty-two patients(61%) presented SF, 28(40%) AF and 18(26%) C. The MMs showed sensitivity and specificity of 97.6% and 92.6% to predict SF; 96.4% and 95.1% to predict AF; and 100% and 98.0% to predict C. Besides that, the MMs correctly classified all 27(39.7%) and 25(38.8%) patients with intermediate values of APRI and FIB-4, respectively. CONCLUSION The metabonomic strategy performed excellently in predicting significant and advanced liver fibrosis in CHC patients, including those in the gray zone of APRI and FIB-4, which may contribute to reducing the need for these patients to undergo liver biopsy.

Nuclear magnetic resonance based metabolomics and liverdiseases:Recent advances and future clinical applications

Metabolomics is defined as the quantitative measurement of the dynamic multiparametric metabolic response of living systems to pathophysiological stimuli or genetic modification.It is an"omics"technique that is situated downstream of genomics,transcriptomics and proteomics.Metabolomics is recognized as a promising technique in the field of systems biology for the evaluation of global metabolic changes.During the last decade,metabolomics approaches have become widely used in the study of liver diseases for the detection of early biomarkers and altered metabolic pathways.It is a powerful technique to improve our pathophysiological knowledge of various liver diseases.It can be a useful tool to help clinicians in the diagnostic process especially to distinguish malignant and non-malignant liver disease as well as to determine the etiology or severity of the liver disease.It can also assess therapeutic response or predict drug induced liver injury.Nevertheless,the usefulness of metabolomics is often not understood by clinicians,especially the concept of metabolomics profiling or fingerprinting.In the present work,after a concise description of the different techniques and processes used in metabolomics,we will review the main research on this subject by focusing specifically on in vitro proton nuclear magnetic resonance spectroscopy based metabolomics approaches in human studies.We will first consider the clinical point of view enlighten physicians on this new approach and emphasis its future use in clinical"routine".

Molecular structure characterization of middle-high rank coal via^(13)C NMR,XPS,and FTIR spectroscopy

Elemental analysis,nuclear magnetic resonance carbon spectroscopy(^(13)C-NMR),X-ray photoelectron spectroscopy(XPS)and Fourier transform infrared spectroscopy(FTIR)experiments were carried out to determine the existence of aromatic structure,heteroatom structure and fat structure in coal.MS(materials studio)software was used to optimize and construct a 3D molecular structure model of coal.A method for establishing a coal molecular structure model was formed,which was“determination of key structures in coal,construction of planar molecular structure model,and optimization of three-dimensional molecular structure model”.The structural differences were compared and analyzed.The results show that with the increase of coal rank,the dehydrogenation of cycloalkanes in coal is continuously enhanced,and the content of heteroatoms in the aromatic ring decreases.The heteroatoms and branch chains in the coal are reduced,and the structure is more orderly and tight.The stability of the structure is determined by theπ-πinteraction between the aromatic rings in the nonbonding energy EN.Key Stretching Energy The size of EB determines how tight the structure is.The research results provide a method and reference for the study of the molecular structure of medium and high coal ranks.

Substituent, Temperature and Solvent Effects on the Keto-Enol EQUILIBRIUM in <i>&beta;</i>-Ketoamides: A Nuclear Magnetic Resonance Study

Substituent, temperature and solvent effects on tautomeric equilibria in several β-ketoamides have been investigated by means of nuclear magnetic resonance spectroscopy (NMR). Keto-enol equilibrium predominates over the amide-imidol one. The relative stability of the individual tautomers and the corresponding equilibrium shifts are explained considering electronic and steric effects and tautomer stabilization via internal hydrogen bonds. In solution, these compounds exist mainly as ketoamide and Z-enolamide tautomers, both presenting intramolecular hydrogen bonds.

地外样品的核分析技术研究进展

地外样品是目前能获取到的来自其他天体的最直接地质证据。研究地外样品的目的在于揭示太阳系及其所含天体的宏观与微观演化过程,并为行星与星际环境和星际移民与外星生命的可能性提供新的见解。地外样品成分的原位或地面实验室精细分析研究对于人类认识天体演化以及我国后续月球探测与资源就地开发利用具有重要的意义。鉴于地外样品的特殊和珍贵,通常优先选用非破坏分析方法对其开展研究。而核分析技术是在实验核物理和核化学基础上发展起来的一门新型学科,是利用粒子与物质的相互作用、辐射效应、核谱学和核效应等基本原理和实验的方法,比如中子活化分析、离子束分析以及X射线荧光光谱分析等,利用其非破坏性、灵敏度高、准确度好和多元素同时分析等优点,非常适合开展地外珍贵样品的分析研究。未来十年是我国深空探测的关键时期,其主要目标是加深对宇宙的认知、拓展人类的活动空间、探寻地外生命信息,并进一步揭示宇宙奥秘与生命起源、了解保护地球以及激发科学探索精神。核分析技术作为对样品无损分析的科学手段,其生命力在于与物理、化学、材料、医学、地质、环境等学科领域的高度融合。随着我国深空探测的发展需求,核分析技术将会在我国月球、小行星、火星等深空探测以及采集的珍贵样品分析中发挥重要的作用。

定量核磁共振波谱法快速测定灭火剂材料中全氟辛烷磺酰基化合物

泡沫灭火剂中全氟辛烷磺酰基化合物(PFOS)的使用受到严格管控.针对灭火剂中PFOS快速测定的需求,建立了基于19F的定量核磁共振波谱(qNMR)检测方法.方法以全氟丁基磺酸钾为标准物质,通过计算全氟丁基磺酸钾的-CF3在化学位移δ-78.94处19F特征峰和PFOS的-CF2在化学位移δ-117.12处19F特征峰的积分面积比值,进而实现PFOS定量分析.经测试,全氟丁基磺酸钾百分含量与定量峰面积线性相关系数为0.9955,检出限为0.024%,定量限为0.080%.8种灭火剂产品的定性测定结果与实际标注情况相吻合,其中4种泡沫灭火剂产品中PFOS含量在0.106%~1.339%之间.研究结果表明,方法受基质干扰小、检测速度快、灵敏度高,可为泡沫灭火剂中PFOS的管控提供可靠的检测方法与数据支撑.

不同溶剂预处理煤在ScCO_(2)作用下的谱学差异及其机制

为了探究溶剂预处理后超临界二氧化碳(ScCO_(2))对煤化学结构的影响,以长治霍尔辛赫贫煤为研究对象,分别用四氢呋喃(THF)、盐酸(HCI)和氢氟酸(HF)对煤样进行预处理,采用傅里叶红外光谱(FTIR)、固体核磁共振(^(13)C-NMR)和X射线衍射(XRD)测试,探讨了ScCO_(2)对预处理煤的化学组成和结构的影响机理。研究表明:①FITR分峰拟合谱图实验曲线基本一致,而各官能团吸收峰位置及峰强度仍出现一定的偏差,酸(HCI、HF)预处理后部分波段脂肪族峰位消失。两类酸预处理顺序不同,对煤中含氧官能团、脂肪结构及芳烃结构作用效果也不相同。HF-HCI处理后芳烃C=C结构和含氧官能团峰强度均增强,而HCI-HF处理后芳烃C=C结构强度减弱,含氧官能团结构峰强度变化不明显。THF预处理后煤样芳烃C=C结构峰强度增强,含氧官能团结构峰强度降低。总体芳烃C=C结构峰强度远大于脂肪族结构和含氧官能团结构的峰强度。②^(13)C-NMR谱中主要官能团谱峰的化学位移出现了一定程度的偏移,芳香碳f_(a)^(B)化学位移向增大的方向偏移。大分子结构参数中,芳香碳含量远大于脂肪碳含量,说明煤大分子结构中芳香碳占主要组成部分。③XRD谱中002峰与101峰衍射强度明显增大,芳香微晶层网面间距d_(002)呈现升高趋势,说明THF、酸(HF、HCI)处理和ScCO_(2)对煤大分子结构产生了一定程度的改造作用,使煤的大分子网络结构变得疏松,进而使微晶结构参数d_(002)整体增大。研究认为,溶剂作用后煤的谱学特征变化不仅与溶剂性质有关,还与无机酸处理顺序有关,由此使得官能团组成和大分子结构不同程度改变,进而影响ScCO_(2)对预处理煤的萃取效果。

黄芩苷与磺化杯[n]芳烃超分子体系包合作用研究

本文研究了中药黄芩中的有效成分黄芩苷与三种不同磺化杯[n]芳烃的包合作用。首先利用荧光光谱法测定了包合物的结合比和结合常数,其次通过核磁共振技术进一步研究了其包合构型,并从分子结构、不同酸碱性等方面探讨了影响包合过程的因素及作用力。结果表明:三种磺化杯[n]芳烃与黄芩苷包合物的包合比均为1:1,当pH为8.04时,磺化杯[8]芳烃与黄芩苷的包结常数最大,为2.45×10^(6)L·mol^(-1).此外,通过对DPPH自由基清除能力进行比较,黄芩苷包合物的抗氧化能力大大增强。恒温加速和光照实验证明黄芩苷包合后形成的超分子体系的残留率远大于黄芩苷自身的残留率。

qNMR法测定片剂苯磺酸氨氯地平的含量

本文利用定量核磁共振波谱法(qNMR)建立了测定片剂苯磺酸氨氯地平含量的分析方法。片剂样品经研磨称量后,加入氘代甲醇为溶剂、1,3,5-三甲氧基苯作为内标物进行混合。混合物经涡旋、超声和离心后取上清液转移入核磁管,对样品采集核磁共振氢谱(1H-NMR)。氢谱中以苯磺酸氨氯地平位于δ5.41的谱峰为检测定量峰,1,3,5-三甲氧基苯位于δ 6.07的谱峰为内标定量峰建立绝对定量方法。1H-NMR实验参数为:90度单脉冲序列,脉冲延迟时间30 s,扫描次数32次,采样温度308 K。实验结果显示苯磺酸氨氯地平与内标物的摩尔比在0.42~8.38的范围内具有良好的线性关系(R2=0.9973),精密度和稳定性试验的相对标准偏差(RSD)分别为0.45%(n=7)和0.44%。对于片剂样品,整个方法(包括目标组份的提取和定量核磁检测)重复性试验RSD为1.69%(n=6);三个不同浓度的加标回收率分别为103.86%、101.20%和99.69%。应用本方法对8个市售品牌的苯磺酸氨氯地平片剂进行了含量测定,结果显示建立的qNMR方法准确度高,重复性好,简便快捷,为片剂药品绝对含量的测定提供了新方法。

农产品检测用脱氧雪腐镰刀菌烯醇纯度标准物质的研制

[目的]本文旨在研制脱氧雪腐镰刀菌烯醇(deoxynivalenol,DON)国家级纯度标准物质,为农产品中DON的检测等工作提供物质基础。[方法]利用质量平衡法和定量核磁共振法对DON纯度标准物质进行纯度定值。质量平衡法包括采用液相色谱面积归一化法测定DON主成分含量,采用卡尔费休库仑法测定纯度标准物质中水分含量,采用顶空气相色谱-质谱法测定挥发性杂质含量,以及采用电感耦合等离子质谱法测定无机离子杂质含量。定量核磁共振法采用苯甲酸为内标,选择合适的共振峰,内标法定量标准物质的纯度,并对标准物质进行均匀性、稳定性检测和不确定度评估。[结果]质量平衡法的纯度定值结果为99.47%,定量核磁共振法定值结果为99.45%,最终所研制的DON纯度标准物质的纯度为99.5%,扩展不确定度为0.4%,均匀性良好,且满足12个月以上的稳定性要求。[结论]本试验所研制的DON纯度标准物质符合国家标准物质技术规范,目前已被批准为国家一级标准物质,并已被用于小麦、玉米等农产品实际检测过程中。

天然气净化厂废水处理过程中溶解性有机物的变化

溶解性有机物(DOM)是废水达标排放标准的重要考虑因素,综合分析废水中DOM的分子组成是对其高效去除的前提。以某天然气净化厂废水为研究对象,采用傅里叶变换离子回旋共振质谱法(FT-ICR MS)和三维荧光光谱(3D-EEMs)从分子层面深入分析氧化过程中DOM的荧光性质、分子组成、质荷比、分子转化。EEM结果表明,废水中主要以类腐殖质物质为主,其次为富里酸类物质。O_(3)/H_(2)O_(2)氧化降低了类腐殖质物质的荧光强度,但DOM降解受限于臭氧与富含电子有机物的反应特性;而O_(3)/H_(2)O_(2)-Fenton联合氧化能大幅降低总荧光强度,有效去除类腐殖质。FT-ICR MS结果表明,O_(3)/H_(2)O_(2)氧化去除了部分CHO类、CHON类DOM,但对CHOS类、CHONS类DOM的去除效果欠佳。多环芳烃和高度不饱和的化合物被臭氧降解为脂肪族类化合物,增加了CHO类DOM含氧量。O_(3)/H_(2)O_(2)-Fenton氧化对CHOS类、CHONS类DOM具有较好的去除效果,去除了大部分多酚化合物,生成具有含氧量更低和饱和度更高的DOM。同时,联合氧化极大地缓解了超滤膜污染,去除了大部分可逆污染和不可逆污染。

常压下酸催化多元醇液化纤维素反应机理的研究

开发农林废弃物高值化利用路径与“深入推进能源绿色低碳转型”国家重大战略需求高度契合。实验探索农业废弃物玉米秸秆中纤维素组分常压酸(H3PO4)催化多元醇[丙二醇(PG)与二甘醇(DEG)混合液]液化反应路径为研究目标,了解酸催化多元醇作用条件下的木质生物质液化反应机理。采用傅里叶红外光谱(FTIR)、凝胶渗透色谱(GPC)、核磁共振波谱(NMR)及热重分析(TGA)对不同反应时间下纤维素液化所得生物油的化学基团、分子量及其分布、分子结构、热解等进行了分析。FTIR检测表明,不同反应时间所得生物油具有相似FTIR特征;液化初期,纤维素降解生成了较多的烃类、醚类和含羰基化合物;液化后期,纤维素中的糖类降解产物、羟基或烯烃与PG/DEG反应生成了难溶于1,4-二氧六环的有机物。GPC分析表明,随着液化的进行,纤维素分子链发生断裂程度加剧,降解生成低分子量(LMW)物质越来越多,降解反应占主导地位;而当反应时间达到某一值时,其降解产物与PG/DEG发生聚合反应产生越来越多的大分子量物质,使生物油的分子量不再降低,即聚合反应占主导地位。^(1)H-和^(13)C-NMR表明,纤维素在液化作用下发生降解使得分子链断裂,仍保留了部分葡萄糖单元结构;随着液化反应的进行,这些结构单元再次发生转化产生LMW化合物;反应继续进行时,这些产物之间或与PG/DEG之间可进行聚合反应,形成结构趋于一致、性质逐渐稳定的新物质。TGA分析结果:生物油中含有70%~85%碳数小于25和5%~10%碳数高于25的化合物,最终残炭率随着反应时间的延长先降低再升高。实验通过研究纤维素在多元醇液化过程中的结构变化,揭示其液化的反应历程,为探索秸秆全组分的液化机理奠定理论基础。