X-射线荧光光谱法测定硅质耐火材料中二氧化硅的测量不确定度评定

介绍了X射线荧光光谱熔融法检测硅质耐火材料中二氧化硅的方法,对X射线荧光光谱熔融法测定硅质耐火材料中二氧化硅的结果产生不确定度的原因进行了分析,根据CSM010100108—2006X-射线荧光光谱法测量结果不确定度评定规范,对其进行了评定,建立了相关数学模型,为其他元素的测量不确定度评定提供了可借鉴的经验。     

应用荧光光谱法检测蓝藻生物量

本研究应用荧光分光光度计,通过对水华鱼腥藻活体荧光光谱的扫描,确定了蓝藻藻蓝蛋白荧光测定的最佳荧光激发波长为620nm,荧光发射波长为650nm,建立了水华鱼腥生物量与藻蓝蛋白特征荧光强度的线性检测关系,表明应用荧光光谱法检测藻蓝蛋白荧光强度反应蓝藻生物量具有特异性和可行性,该方法具有简便、快速、操作简单、样品无需处理等优点。为测定蓝藻生物量提供了新的检测方法。     

荧光光谱法研究葛根素与牛血清白蛋白的相互作用

在不同温度下,采用荧光猝灭光谱法和同步荧光光谱法研究了葛根素与牛血清白蛋白(BSA)相互作用的光谱学行为。根据在292K和311K温度下葛根素对BSA的荧光猝灭作用,利用Stern-Volmer方程及双倒数方程对实验数据进行处理,结果表明葛根素对BSA的荧光猝灭作用属于静态猝灭过程。根据Frster非辐射能量转移理论计算出了葛根素与BSA间的结合距离r=2.84nm,结合常数(Kb)分别为1.334×105mol/L(292K)和4.513×105mol/L(311K)。热力学数据表明,二者主要靠静电引力结合。采用同步荧光光谱法分析了葛根素对BSA构象的影响。     

荧光光谱检测技术在茶饮料成分分析中的应用

荧光光谱检测技术已广泛用于有机物的定性和定量分析,取得了良好的效果.本文介绍了荧光光谱法的检测原理和检测系统的组成.采用该荧光检测系统在激发波长300～550nm、发射波长310～710nm处检测了茶饮料的荧光光谱,通过对荧光光谱的分析,建立了主要成分的荧光光谱特征数据库.该方法有助于解决市场上真假茶饮料的质量鉴别问题.     

偏最小二乘法荧光光谱预测啶虫脒农药残留

为满足农药残留多组分含量测定的要求,对荧光光谱法测量农药残留得到的混合光谱进行分离,基于偏最小二乘法建立荧光光谱测量系统校正模型,并预测啶虫脒残留量。选择20个特征波长,采用交互验证方法,以预测残差平方和为评价指标,确定最优主成份数,获得了最佳分析模型。通过对预测集进行测试,滤纸带和西红柿表面啶虫脒残留浓度为100,220,450mg/kg的预测值分别是101.45,222.91,440.08mg/kg和98.67,208.56,419.22mg/kg,预测值和真实值的相关系数分别达到0.996和0.988。实验显示,采用偏最小二乘法结合荧光光谱测定啶虫脒农药残留,具有快速、无损、测量精度高等特点,并表明该方法用于定量分析复杂多组分体系是有效的。     

测定小牛胸腺DNA含量的荧光新方法研究

采用荧光光谱法对多种荧光试剂与小牛胸腺DNA(ctDNA)结合后的光谱特征做了研究,实验结果发现ctDNA不仅可以使夜蓝(NB)的荧光增强,而且在一定浓度范围之内体系的荧光增强程度与ctDNA的量呈线性关系,据此,建立了一种测定ctDNA含量的荧光新方法。当pH值为6.4,反应温度为25℃,反应时间为30min,NB的浓度为2.0×10-5mol.L-1时,ctDNA的浓度在0.01～0.8 g.mL-1范围内,体系的ΔF与ctDNA的浓度呈良好的线性关系,线性方程为:ΔF=627.85c+6.2547(c:g.mL-1),r=0.9986,检测限为4.2×10-5g.mL-1。本方法首次成功地应用于果树榛子中DNA的测定,回收率为96.58%～102.35%,结果令人满意。     

食品(药品)安全时代的分子光谱法

本文对分子光谱法中最常用的红外光谱法、近红外光谱法、拉曼光谱法、紫外可见分光光度法、荧光光谱法以及超光谱成像技术等在食品(药品)安全领域的研究、应用、存在问题及发展前景等方面进行了综述.重点阐述了故意掺杂(比如保健品掺杂化学药品等)、无意残留(比如果蔬农药残留等)、其他物种混淆(比如他种药品冒充另一种化学药品等)三种情况下,采用光谱分析的特点和难点,尤其是这些分析对象对信息处理以及硬件设备的要求.在食品(药品)安全时代,需要分子光谱法大有作为,也大有可为.     

三维荧光二阶校正与非线性回归同时测定多个有机化合物

由于内嵌的二阶优势,基于三维数据分解的二阶校正技术在例行分析中具有巨大的潜力。三维荧光光谱法是描述荧光强度同时随激发波长和发射波长变化的关系谱图,能提供更完整的荧光光谱信息。平行因子分解和交替三线性分解算法是对不同荧光物质的光谱进行分离的高效算法,可从复杂混合物的三维荧光光谱数据矩阵中将其各自的特征荧光光谱分解出来。邻苯二酚、对苯二酚、酪氨酸、吲哚是结构非常相似的有机化合物,光谱重叠严重,很难用常规方法直接定量检测。本实验将二阶校正算法、神经网络非线性回归与三维荧光光谱法结合,探究了四组分同时分离检测方法,实验结果确认了该方案的可行性,通过比较也发现两种二阶校正方法无明显的差异。该方法在环境分析中具有巨大潜力。     

粉末压片-X射线荧光光谱法测定碳酸盐中的CaO和MgO

采用帕纳科Axios4．0X射线荧光光谱仪，建立了对碳酸盐中的CaO、MgO含量测定的X射线荧光光谱法。称取300目的样品，用低压聚乙烯镶边衬底，32MPa压力制备碳酸盐样品，用X射线荧光光谱法测定碳酸盐中的CaO、MgO含量；采用国家标准物质验证方法，其结果与标准值相符，CAO的精密度（RSD，n=9）小于0．3％，MgO的精密度（RSD，n＝9）小于11％。该方法制样方便、快捷、经济，分析周期短，测量准确度、精密度较好，与容量法和熔片法结果一致，可以满足并适用于常规碳酸盐中的CaO、MgO含量的测定。     

X射线荧光光谱法测定石灰石中SiO2、CaO、MgO的含量

采用硼酸镶边衬底制备石灰石样片 ,用波长色散X射线荧光光谱法测定了石灰石中SiO2 、CaO、MgO含量。结果表明 ,本法测量准确度 ,精密度较好 ,所得结果与化学分析结果一致     

Recent Developments in Frequency-Domain Fluorometry

I. SUMMARY

Phase-modulation fluorometry is the frequency-domain analogue of time-resolved fluorescence spectroscopy. During the past three years we witnessed the development of variable-frequency phase-modulation fluorometers with modulation frequencies from 1 to 220 MHz. These instruments provide impressive resolution of multi or non-exponential fluorescence decays. To introduce these instruments we describe their design and operational principles. To illustrate the obtainable resolution we present results for the resolution of two and three-component mixtures of fluorophores, the resolution of complex anisotropy decays from non-spherical molecules and the determination of time-resolved emission spectra in the presence of time-dependent spectral relaxation. At present, the resolution obtainable with the frequency-domain fluorometers appears to be at least equivalent to that obtained with pulsed mode-locked laser sources with single photon counting. These mode-locked sources can also be used for phase fluorometry, as described elsewhere in this volume by Gratton and co-workers.     

便携式全光纤荧光计的实验室检测与分析

本文简要介绍一种新型便携式全光纤荧光计的基本工作原理，主要技术指标，按标准浓度油水混合液的配制方法。配制出的不同浓度的O#柴油进行检测试验，通过对原始数据和检测结果的分析表明，该仪器达到技术指标要求，可用于现场实时检测亦可用于实验室检测分析。     

Single Photon Counting With Synchronously Pumped Dye Laser Excitation

ABSTRACT

This article reviews the advances that have been made in the technique of pulse fluorometry with time-correlated single photon counting detection brought about by the introduction of mode-locked synchronously pumped dye laser excitation. High repetition rates and small pulse width permit high data collection rates and excellent time-resolution. A modern pulse fluorometer which allows efficient measurement of fluorescence decay curves as well as automated measurement of time-resolved fluorescence spectra and of fluorescence anisotropy decays is described in detail.     

牛肉样品中维生素C的HPLC测定

肉制品中维生素C的测定常用比色法和荧光法。本文描述一种简单快速的高压液相色谱法(HPLC)分析牛肉中少量Vc。这种方法使用梯度洗脱(0 1%草酸溶液+乙腈,96∶4 ) ,具有分辨率高,洗脱快,回收率(99% )和相对误差小(4 2 % )等优点。     

原子吸收仪氢化物检测器与原子荧光检测硒含量检测方法对比试验

本文利用原子吸收仪氢化物检测器与原子荧光检测不同类别的几种食品中的硒含量,通过对检测方法的对比试验,结果表明:通过试验两台仪器的加标收率都在标准允许的范围之内,说明我所两台仪器是稳定可靠的。通过比对试验说明,我所多年来使用的氢化物原子吸收方法检测食品中硒含量的检测方法数据是稳定可靠的,数据再现性较强。通过数据比较可以看出我所氢化物原子吸收检测食品中硒含量,数据的稳定性优于我所刚刚购置的原子荧光光度计。     

叶绿素α的激光光致发光机理及其浓度测量新方法研究

介绍了一种以红光半导体激光器作为荧光激发光源,结合光纤光谱技术测量水体中叶绿素α浓度的新方法。通过分析叶绿素α的激光光致发光机理,得出了水体中叶绿素α荧光发射光谱的相对荧光峰值强度与叶绿素α浓度的近似线性关系。实验结果表明,在红光半导体激光器激励下根据叶绿素α的荧光发射光谱直观地判断叶绿素α的浓度这种方法完全可行,由此为研制叶绿素α荧光仪提供了一种新的光源选择,并为实现现场实时监测海水中叶绿素α浓度提供了实验依据。     

Direct evaluation of fluorescence in single renal epithelial cells using a mitochondrial probe (DASPMI)

The study of distribution and quantitation of a fluorescent probe in living epithelia with the aid of an inverted microscope requires that individual cells can be analysed without optical interference from adjacent cells. This report describes the application of fluorescence microscopy and fluorometry to a recently developed in vitro culture system of renal epithelial cells. Epithelial cells derived from the mammalian renal cortical collecting tubule (CT) and the thick ascending loop of Henle (TAL) are cultivated as continuous monolayers in serum-free, hormone-supplemented media. A specific mitochondrial marker (DASPMI) is added to the medium and incorporated into the cytoplasm. The microscopic image reveals that the mitochondrial fluorescence distribution differs between CT and TAL cultures. The fluorometric quantitation shows a normally distributed histogram of medium-range intensity in TAL cell cultures while CT cultures exhibit a two-peak pattern of mitochondrial fluorescence distribution among epithelial cells.     

Confocal pH imaging of microscopic specimens using fluorescence lifetimes and phase fluorometry: influence of parameter choice on system performance

We investigate the performance of confocal pH imaging when using phase fluorometry and fluorophores with pH-dependent lifetimes. In these experiments, the specimen is illuminated by a laser beam, whose intensity is sinusoidally modulated. The lifetime-dependent phase shift in the fluorescent signal is detected by a lock-in amplifier, and converted into a pH value through a calibration procedure. A theoretical investigation is made of how the different system parameters will influence the results concerning sensitivity and noise. Experiments carried out with the fluorophore SNAFL-2 support these theoretical predictions. It is found that, under realistic experimental conditions, we can expect a pH change of 0.1 units to be easily detected in an 8-bit digital image. However, the pixel-to-pixel root mean square noise is often of the order of one pH unit. This comparatively high level of noise has its origin in photon quantum noise. pH measurements on living cells show a systematic deviation from expected values. This discrepancy appears to be the result of fluorophore interaction with various cell constituents, and is the subject of further investigation.     

Fluorescence recognition of proteinaceous binders in works of art by a novel integrated system of investigation

Fluorescence microscopy and microspectrofluorometry are important tools in the characterization and identification of proteins, offering a great range of applications in conservation science. Because of their high selectivity and sensitivity, the combination of these techniques can be exploited for improved recognition and quantification of proteinaceous binders in paintings and polychromed works of art. The present article explores an analytical protocol integrating fluorescence microscopy and fluorometry for both identification and mapping of proteinaceous binders (in particular egg and glues) in paint samples. The study has been carried out on historically accurate reconstructions simulating the structure and composition of tempera and oil paints containing these binders. To assess the spatial distribution of specific proteins within the paint layers, cross‐sections from the reconstructions were analyzed by fluorescence imaging after staining with an exogenous fluorophore. Reference fluorescence spectra for each layer were acquired by a multichannel spectral analyzer and compared after Gaussian deconvolution. The results obtained demonstrated the effectiveness of the integrated protocol, highlighting the potential for the use of fluorescent staining coupled with microspectrofluorometry as a routine diagnostic tool in conservation science. The current work creates a set of fully characterized reference samples for further comparison with those from actual works of art. Microsc. Res. Tech., 2011. © 2011 Wiley Periodicals, Inc.     

Joint stiffness identification of an ultra-precision machine for machining large-surface micro-features

In this study, to more quantitatively evaluate the structural characteristics of an ultra-precision machine for machining large-surface micro-features, the joint stiffnesses of hydrostatic guideways and bearings were identified based on a virtual prototype and compliances of the ultra-precision machine. The virtual prototype of the ultraprecision machine was constructed to include the joint stiffnesses to be identified, and the joint stiffnesses were identified through an optimization problem in order to minimize the error between the compliances measured from the physical prototype and the compliances predicted from the virtual prototype. In particular, the validity of the identified joint stiffnesses was verified by the fact that the loop stiffnesses of the ultra-precision machine predicted from the virtual prototype and the identified joint stiffnesses coincided well with those measured from the physical prototype.