激光拉曼光谱内标法直接测定乙醇浓度

采用激光拉曼光谱对醇类样品中的乙醇含量进行直接测定。通过不同浓度乙醇的拉曼光谱特征峰(CCO面内伸缩振动884cm-1)与本底水峰组成相对强度比,建立线性回归方程,结果表明,线性范围为4%~40%,线性相关系数为0.9975;检出限为1.02%;回收率为82.0%~105.0%。对白酒、清酒、杨梅酒和医用酒精棉进行了测定,其乙醇平均浓度分别为36.1%、15.5%、23.7%和79.1%;RSD分别为0.22%、1.75%、2.49%和2.76%。此方法具有快速、简便、直接、绿色、对样品无损等优点,适用于白酒类、医用酒精等乙醇含量的检测。     

激光拉曼光谱内标法直接测定甲醇含量

<正>激光拉曼光谱法作为一种新型无损检测技术,广泛应用于样品的定性、定量分析[1-3]。目前,样品中甲醇的定量分析方法常用的有气相色谱法[4]、分光光度法[5]和传感器法[6]等。本工作通过不同浓度的甲醇拉曼光谱特征峰(1 016.46cm-1)与乙醇的拉曼光谱特征峰(877.95cm-1)组成相对强度比,建立线性回归方程。本法具有测定简单、操作方便,无需添加其他化学试剂,可用于甲醇含量的直接检测。     

拉曼光谱法定量分析焦磷酸根离子的含量

应用拉曼光谱技术研究了焦磷酸钾、硝酸钾、磷酸二氢钾、乙二胺四乙酸钠等十余种可溶性盐水溶液以及它们的混合物溶液的拉曼光谱特征,考察了共存组分对焦磷酸根拉曼光谱特征峰的影响;建立了基于拉曼光谱技术定量分析溶液中焦磷酸根离子含量的方法。结果表明,以硝酸钾为内标物,保持被测溶液pH 11,焦磷酸根离子拉曼光谱特征峰强度与硝酸根离子拉曼光谱特征峰强度之比值对焦磷酸根浓度呈良好的线性关系,所得线性回归方程为y=1.2110x+0.1515,相关系数R2=0.9996;已经研究过的十余种可溶性盐共存物几乎不干扰焦磷酸根离子的定量分析。     

激光拉曼光谱法测定模拟高放废液中钼酸根

建立激光拉曼光谱法测定模拟高放废液中钼酸根的分析方法。考察了拉曼光谱法测量钼酸根的主要影响因素。以硝酸根作为内标物,在选定的实验条件下,钼酸根与硝酸根的拉曼光谱特征峰强度比值与钼酸根浓度呈良好的线性关系,钼酸根浓度分别为0.002~0.08,0.05~0.80 mol/L时,线性方程分别为y=247c–0.178 8,y=11.36c–0.112 8,r~20.999,方法检出限为0.001 mol/L。采用该方法测定模拟高放废液中的钼酸根,测定值与配制值相比,相对误差小于5%,测量结果的相对标准偏差小于4%(n=6)。该方法操作简便、检测快速、制样简单、取样量小。     

用于电化学界面研究的共焦显微拉曼光谱技术(英文)

系统地介绍了将共焦显微拉曼光谱系统用于电化学界面研究的方法 ,包括铂电极的粗糙和电化学拉曼电解池的设计 .进行了铂上氢、氧和氯共吸附的拉曼光谱研究 .通过对甲醇氧化过程的现场跟踪 ,提出检测界面区溶液浓度变化和计算溶液 pH值的方法 .实验表明拉曼光谱技术可作为研究实际应用体系的重要工具 .     

可待因及福尔可定的密度泛函理论计算模拟和表面增强拉曼光谱测定北大核心CSCD

运用密度泛函理论(DFT)对可待因及福尔可定进行几何构型优化,从而对标准品粉末的拉曼光谱的振动模式进行指认和归属,并与低浓度水平标准溶液的表面增强拉曼谱图进行比较。进一步优化了表面增强拉曼光谱检测条件,并摸索可待因及福尔可定的测定下限及定量分析的可行性。结果表明,可待因及福尔可定大部分特征峰拉曼位移的理论计算值、拉曼光谱测定值、表面增强拉曼光谱测定值是一致的,但会有一定程度的蓝移和红移;可待因、福尔可定的测定下限均为10 mg·L^(-1)。可待因在631.29 cm^(-1)和1 595.26 cm^(-1)处、福尔可定在628.58 cm^(-1)和1 251.41 cm^(-1)处的特征峰强度比值,与其对应的质量浓度(40~100 mg·L^(-1))呈线性关系。对空白基质进行加标回收试验,可待因和福尔可定的回收率分别为99.0%~105%和102%~104%,测定值的相对标准偏差(n=5)分别为5.3%,5.9%。上述方法可为这两种管制药品提供拉曼光谱检测的理论依据和快检支持。     

密度泛函理论及光谱对CuCl2溶液中微团簇的研究

利用密度泛函理论和拉曼光谱对氯化铜溶液第一溶剂化层中的微团簇进行了研究。采用B3LYP方法对溶液中可能存在的团簇构型进行优化,从动力学和热力学方面分析得出溶液中团簇结构信息。理论拉曼光谱在100~500 cm~(-1)主要为Cu—O的伸缩振动峰,3400~4000 cm~(-1)范围内为O—H的对称和不对称伸缩振动。实验光谱在200~340 cm~(-1)出现明显新峰,位于2500~4000 cm-1的O—H伸缩振动峰随着溶液浓度的增加,峰的强度逐渐减小,峰形有明显变化。实验光谱和理论光谱验证和比对,表明溶液的实验光谱中产生的新峰为Cu—O振动,CuCl_2水溶液中产生短程离子相互作用及溶剂化现象,且随着溶液浓度的增加,溶剂化数目减小。     

用傅立叶变换拉曼光谱法测定乙醇浓度

激光拉曼光谱可以迅速准确的分析混合溶液的成分及比例,为溶液浓度检测提供了一种新的方法.以乙醇溶液为例,研究用拉曼光谱法分析溶液的浓度.     

基于拉曼光谱成像的食品中化学添加剂的无损检测

基于拉曼光谱成像技术对小麦粉中过氧化苯甲酰和L-抗坏血酸进行快速、 无损、 原位检测, 并对2种添加剂的空间分布进行了可视化研究. 采用实验室自行搭建的线扫描式拉曼光谱成像系统, 激发光源波长为785 nm, 有效光谱范围为0~2885.7 cm^-1. 分别在小麦粉中添加含量为0.1%~30%的过氧化苯甲酰和L-抗坏血酸, 对制备的样品进行拉曼光谱扫描, 选取感兴趣区域的光谱信号进行平均, 得到平均光谱代表该样品的拉曼信息. 分别选取过氧化苯甲酰和L-抗坏血酸的2个特征峰, 与该物质在小麦粉中的含量建立线性关系, 其决定系数R²分别为0.9828 和0.9912. 采集的特征波段拉曼图像经过自适应迭代重加权惩罚最小二乘(airPLS)方法扣除荧光背景后, 选取合适的特征峰强度作为阈值, 对校正拉曼图像进行二值化分析, 得到添加物的空间分布可视化图像. 该方法与点检测拉曼技术相比, 具有检测结果准确且检测时间较短的优势, 且可以实现不均匀样品中多种物质的同时检测与分布可视化.     

基于单细胞拉曼光谱技术的葡萄球菌黄素生物合成分析

利用光镊拉曼光谱技术研究吲哚对金葡菌细胞中葡萄球菌黄素合成的抑制作用以及色素含量在分批培养过程中的动态变化。收集经不同浓度吲哚(终浓度为0,0.2,0.6,0.8,1.2和1.5 mmol/L)处理后的以及不同培养时间的金葡菌单细胞的拉曼光谱,以光谱1523 cm-1峰强度表征色素含量,并与紫外可见分光光度法得到的结果进行比较。结果表明,细菌拉曼光谱1523 cm-1峰强度与分光光度法测得的色素含量有良好的线性关系,相关系数达0.9772;群体和单细胞水平的光谱数据均表明,吲哚可剂量依赖性地抑制葡萄球菌黄素的合成,色素含量降低幅度超过70%;在分批培养中细菌色素含量在对数生长中期(12 h)达到最大值,各个时间点的群体内部细胞间色素含量的异质性较小,RSD在39.2%~61.1%之间。本研究表明光镊拉曼光谱技术是一种在单细胞水平分析葡萄球菌黄素含量的可靠方法。     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

Synthesis of pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles by Curtius reaction in Morita-Baylis-Hillman derivatives

Synthesis of substituted pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles from the Morita-Baylis-Hillman derivatives of acrylates via saponification followed by Curtius reaction is described.     

正丁胺对激光染料荧光谱影响的研究

用正丁胺作为碳源,采用射频辉光放电制备碳膜,选用激光染料R6G和聚乙二醇混合液作为蒸气源,采用单源热蒸发,在蒸发室与染料同时沉积得到混合膜,用拉曼光谱和红外光谱分析了碳膜的结构和键合方式,分析表明:碳膜中存在胺基团和氢原子.混合膜的荧光谱测量结果表明,认为正丁胺对染料荧光谱的影响是因为胺基和氢原子的存在.     

Cu0-catalysed 1,3-dipolar cycloadditions of α-amino acid derived N,N-cyclic azomethine imines to ynones

A series of 20 CuAIAC reactions between eight 4-acylamino substituted pyrazolidine-3-one-1-azomethine imines and four terminal ynones were performed using Cu⁰ as catalyst. The corresponding fluorescent cycloadducts were obtained in very high yields upon simple workup. Thus, Cu-metal turned out to be a better catalyst than Cu^I in terms of yield and ease of isolation. Availability of azomethine imines, mild reaction conditions, and simple workup enable a “click” access to libraries of densely substituted 2,3-dihydro-1H,5H-pyrazolo[1,2-a]pyrazol-1-ones. Reactivity of differently substituted dipoles was evaluated experimentally and by quantum chemical methods (DFT).     

Synthesis and antioxidative/anti-inflammatory activity of novel fullerene–polyamine conjugates

(E)-4-(Fullerenopyrrolidin-1-yl)-3-methylbut-2-enoic acid and its corresponding succinimidyl ester, readily obtained through Prato-type modification of C₆₀, were used for the selective N-acylation of polyamines. The thus obtained conjugates were evaluated for their antioxidative and anti-inflammatory activity and their cytotoxicity was determined. Members of this family of compounds showed interesting anti-lipid peroxidation, anti-lipoxygenase and anti-inflammatory activity and comparable cytocompatibility to spermidine.