Determination of Prostate-Specific Antigen in Serum and a Reference Material by On-Chip Immunoaffinity Chromatography

Glycoprotein tumor markers are striking examples of heterogeneous analytes. The complexity of their structural forms in biological fluids is generally not reflected in reference materials. Therefore, they are not specified to consist of a distinct form, but rather to contain a mixture of molecular species. In this study, the question of the heterogeneity of free prostate-specific antigen (free PSA) is addressed in reference materials to define the immunoreactive molecular species and compare them to those in clinical serum. The reference material for free PSA and serum samples of subjects with benign prostatic hyperplasia and prostate cancer was examined for immunoreactivity to epitope I-specific anti-free PSA antibody using on-chip immunoaffinity chromatography in combination with mass spectrometry for the determination of bound forms. The mass spectra of the reference material for free PSA and clinical serum, obtained by on-chip immunoaffinity chromatography, were similar. The cluster of major free PSA-immunoreactive peaks at 28–29 kDa corresponding to the mature glycosylated PSA molecule overlapped in both analytes. However, the reference material displayed a more restricted pattern of low molecular mass species corresponding to nicked PSA fragments or PSA degradation products. The PSA concentration in clinical serum seems to consist of more species than equivalent concentrations of reference material. Regarding analysis of heterogeneous proteins, immunoaffinity capture combined with mass-specific detection represents a rapid means for selective detection of distinct molecular species, exceeding the analytical performance of current formats of immunoassays.     

鱼肉环丙沙星标准样品的研制

介绍了以鲤鱼鱼肉作为基质含有环丙沙星的标准样品的研制过程。通过添加环丙沙星养殖鲤鱼获得样品,用液相色谱-串联质谱法对样品进行均匀性和稳定性检测,采取8个实验室协作定值的方法对样品进行定值检测,进行了标准值的计算和不确定度评估;研究表明获得的样品均匀性良好,稳定性至少17个月,可以用于检测质量控制和科研工作。     

Metrological traceability: I make it 42; you make it 42; but is it the same 42?

The paper reproduces a talk given at a 2-day symposium on quality assurance in chemistry held in Brisbane, Australia in 2005. Intended for an audience of analysts in the field, the theme of the symposium drew inspiration from the series of books by Douglas Adams “The Hitchhiker's Guide to the Galaxy”. An introduction to basic concepts of metrological traceability is followed by a discussion of practical steps to ensure metrological traceability of field measurement results. The relationship between metrological traceability and comparability of measurement results is discussed. To achieve metrological traceability in the field, the use of appropriate certified reference materials for calibration is recommended. Examples of atmospheric carbon dioxide and roadside breathalyzer measurements are given.

Application of point-to-point matching algorithms for background correction in on-line liquid chromatography-Fourier transform infrared spectrometry (LC-FTIR)

A new background correction method for the on-line coupling of gradient liquid chromatography and Fourier transform infrared spectrometry has been developed. It is based on the use of a point-to-point matching algorithm that compares the absorption spectra of the sample data set with those of a previously recorded reference data set in order to select an appropriate reference spectrum. The spectral range used for the point-to-point comparison is selected with minimal user-interaction, thus facilitating considerably the application of the whole method. The background correction method has been successfully tested on a chromatographic separation of four nitrophenols running acetonitrile (0.08%, v/v TFA):water (0.08%, v/v TFA) gradients with compositions ranging from 35 to 85% (v/v) acetonitrile, giving accurate results for both, baseline resolved and overlapped peaks.     

Non-parametric estimation of reference intervals in small non-Gaussian sample sets

This study aimed at validating common bootstrap algorithms for reference interval calculation.We simulated 1500 random sets of 50–120 results originating from eight different statistical distributions. In total, 97.5 percentile reference limits were estimated from bootstrapping 5000 replicates, with confidence limits obtained by: (a) normal, (b) from standard error, (c) bootstrap percentile (as in RefVal) (d) BCa, (e) basic, or (f) student methods. Reference interval estimates obtained with ordinary bootstrapping and confidence intervals by percentile method were accurate for distributions close to normality and devoid of outliers, but not for log-normal distributions with outliers. Outlier removal and transformation to normality improved reference interval estimation, and the basic method was superior in such cases. In conclusions, if the neighborhood of the relevant percentile contains non-normally distributed results, bootstrapping fails. The distribution of bootstrap estimates should be plotted, and a non-normal distribution should warrant transformation or outlier removal. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

The establishment of a quality evaluation system of reference materials

Reference materials have been applied widely to ensure the traceability, comparability and reliability of measurement results. To achieve this purpose, the quality of reference materials (RMs) themselves is surely an important aspect to be pay attention to. A quality evaluation system of RMs has been established through the project “The National Sharing Platform of Reference Materials” in China to give a reliable assessment on the quality of RMs from various sources including the accuracy and comparability of their property values, which is very useful to promote the appropriate selecting and using of RMs in China. Through the application of National Metrology Institute calibration and measurement capabilities on the basis of the international mutual recognition arrangement, it can also provide a powerful supplement to the current activities such as the accreditation of RM producers in the construction of a global harmonized quality control and assurance system of RMs.     

外场多光轴瞄准偏差测试的基准光轴建立方法

提出一种针对外场真实环境下可见光、激光和红外多光轴瞄准系统瞄准偏差测试的基准光轴建立方法.采用精密大地测距、测角技术获得观测仪器站址坐标、基准光轴方向和靶标中心位置,通过对标定靶标上的中心点作测距和测角观测,并对基准光轴方向大气折射和地球曲率引入的误差进行改正,获得基准光轴、激光和红外系统在靶标上的精确位置.理论分析和实际测试结果表明,该方法具有理论严密、测量准确度高、工程上易于实现的优点,在2 km范围内基准光轴误差小于4.5″,完全满足多光谱多光轴动态瞄准偏差测试中基准光轴准确度的要求.     

Preparation of carbon-aerogel polypyrrole composite for desalination by hybrid capacitive desalination method

Capacitive Deionization (CDI) is an emerging technology with great potential applications. Most researchers view it as a viable water treatment alternative to reverse osmosis. This research reports the preparation and application of a carbon aerogel polypyrrole (CA-PPy) composite for the desalination of NaCl solution by the hybrid CDI method. The carbon aerogel (CA) was prepared from a Resorcinol / Formaldehyde precursor by the sol–gel method. The aerogel obtained from the sol–gel was then pyrolysed in a tube furnace to form CA. Polypyrrole (PPy) was prepared by the Oxidative chemical polymerisation of pyrrole, ferric chloride hexahydrate (oxidant), and sodium dodecyl sulfate (dopant). A composite of CA and PPy was then prepared and used to modify carbon electrodes. The CA-PPy composite was characterised to verify its composition, morphology, thermal properties, and functional groups. The electrochemical properties of the material were determined by Cyclic voltammetry (CV) and Electrochemical impedance spectroscopy (EIS) tests. The electrochemical tests were done using a GAMRY potentiostat electrochemical workstation, a 1.0 M KCl was used as the electrolyte, and the applied potential window was (-0.2 to + 0.6) V for the CV test. The EIS test was done with the same concentration of KCl electrolyte at an applied potential of 0.22 V and at a frequency range of (0.1 – 100, 000) Hz. The optimal specific capacitance of the CA is 115F/g, and that of the composite is 360.1F/g, they were both obtained at a scan rate of 5 mV/s. The CDI desalination study of the CA-PPy composite showed a salt adsorption capacity (SAC) of 10.10 mg/g (300 mg/L NaCl solution) – 15.7 mg/g (800 mg/L NaCl solution) at 1.2 V applied voltage. The salt recovery efficiency of the electrode material in the 300 mg/L solution is 27 %, in the 500 mg/L solution, it is 20.12 %, and in the 800 mg/L solution, it is 15.41 %. The electrode material also showed good electrochemical stability after nine cycles of ion adsorption/desorption study.     

完全氧化DZ125的双向反射特性实验研究

作为燃气轮机的核心部件，涡轮叶片长期在上千度的高温下工作，为了保证叶片安全可靠地运行，需要对其温度进行实时的监测。辐射测温是目前涡轮叶片非接触式测温的主流方法，其测温精度与叶片材料反射特性关系密切，如何预测不同方向反射能量的大小，减小反射辐射对测温结果的影响是目前研究的难点。为了预测叶片反射能量大小，提高辐射测温的准确性，对涡轮叶片常见材料——完全氧化DZ125的双向反射分布函数(BRDF)进行研究。采用对比法作为实验测量的方法，先分析了BRDF对比法测量原理及数据处理方法，之后自主搭建了试验台，在温度分别为25, 900和1 100℃,波长分别为1 060, 1 550和1 908 nm的条件下，控制入射天顶角及反射天顶角在0°～60°范围变化，方位角在0°～180°范围变化，测量计算出了多组BRDF值，分析了各种因素对完全氧化DZ125的BRDF的影响。最后采用Modified Phong模型对BRDF测量值进行了拟合，并与实验测量结果进行了对比，得到了较好的结果。研究结果表明，温度、波长对完全氧化DZ125的BRDF影响较小，在涡轮叶片工作的温度范围变化不大，辐射波长变化不大时，...