扫描记录式分光光度计的数字化升级改造

用４８６计算机、数据采集Ａ／Ｄ卡,Ｃ语言编写运行程序,取代Ｘ－Ｙ记录仪,实现扫描记录式分光光度计的数字化改造。     

An automated facility for neutron activation analysis

A fully automated neutron activation analysis (NAA) facility has been constructed at the Whiteshell Nuclear Research Establishment. This high-capacity facility has been designed for use with a wide variety of neutron sources, including Canada's SLOWPOKE II and MAPLE research reactors. Its pneumatic transfer system is driven by a Square-D Model 500 programmable controller, linked in turn to a Nuclear Data ND6700 computer/spectrometer. Custom software for data entry and system control has been combined with Nuclear Data software for gamma-spectrum acquisition and processing to create a flexible, easy-to-use facility for NAA. Its design and performance are discussed.     

Echtzeit-Datenerfassungssystem mit minimaler hardware für den Einsatz in der Routine-Massenspektrometrie im organischen Laboratorium

A low-cost on-line digital computer system for data acquisition and reduction of mass spectral information from a single focusing mass spectrometer is described. The data system is designed to handle the problems most commonly encountered in routine applications in organic chemistry. By using sophisticated programming concepts a versatile user oriented system is realised on a minimal hardware configuration. Detailed information about data flow and logical structure of the programs is given.     

毛细管电泳扫描伏安电化学法分离检测肾上腺素、氯丙嗪和异丙嗪

采用自制的高效毛细管电泳扫描伏安电化学检测装置,在磷酸盐缓冲溶液中进行了肾上腺素、异丙嗪和氯丙嗪的分离检测,在优化的条件下获得了较好的检测重现性和低的检出限。结果表明,采用扫描伏安电化学方法不但能够减少电极的污染,而且可以在电泳过程中获得被测物质的伏安特性及检测体系的动态伏安图,更有利于被测物质的识别。     

A computer system for measuring fast-scan lowresolution mass spectra

A microprocessor-based satellite computer system (MASDAT) controls a low-resolution, fast-scan mass spectrometer for the measurement of series of spectra. Special digitization hardware (logarithmic A/D converter) and software algorithms are necessary to achieve a dynamic range (ratio of highest to lowest intensity) of about 10⁵ in peak heights. Up to three MASDAT satellites can be connected to a host computer. Synchronized parallel programs in the host system communicate with the operator, calibrate the mass scale, print an interscan report, and store final spectra and, optionally, unreduced data on mass storage devices. Host software is described for a RSX11M and for a VAX/VMS operating system.     

A computer controlled photon counting flame emission spectrometer

An automated emission spectrometer has been developed around a simple commercial instrument. The manner in which a computer is used for control and the way data are acquired and assimilated are discussed. The interfacing to the computer is described, sample programs are illustrated and methods of analyses are given. Sensing is achieved through photon counting. The linearity of the system has been examined and it was found that, for lithium, quantitative results can be obtained with an accuracy of 1 per cent for a concentration range of four orders of magnitude. The time required for analysis is discussed and, although the spectrometer is serial in nature, the increased information rate obtained through photon counting results in high speed data acquisition.     

Experimental apparatus for investigation of sputtering and secondary ion emission induced by energetic ion beams

The construction of an experimental apparatus, for investigation of implantation, secondary ion emission and sputtering processes, during irradiation of samples with an ion beam of up to 70 keV energy, is described. The basis of the apparatus is an electromagnetic mass separator equipped with a quadrupole mass spectrometer located in the collector chamber. The computer data acquisition control system makes it possible to perform the experimental measurements with high accuracy and precision. Preliminary results of secondary ion mass spectral measurements, obtained for C, Al, Si and Cu targets bombarded with Ar(+) and Kr(+) ions, are presented.     

A New kHz Velocity Map Ion/Electron Imaging Spectrometer for Femtosecond Time-Resolved Molecular Reaction Dynamics Studies

A new velocity map imaging spectrometer is constructed for molecular reaction dynamics studies using time-resolved photoelectron/ion spectroscopy method.By combining a kHz pulsed valve and an ICCD camera,this velocity map imaging spectrometer can be run at a repetition rate of 1 kHz,totally compatible with the fs Ti:Sapphire laser system,facilitating time-resolved studies in gas phase which are usually time-consuming.Time-resolved velocity map imaging study of NH₃ photodissociation at 200 nm was performed and the time-resolved total kinetic energy release spectrum of H+NH₂ products provides rich information about the dissociation dynamics of NH₃.These results show that this new apparatus is a powerful tool for investigating the molecular reaction dynamics using time-resolved methods.     

Automated mass correction and data interpretation for protein open-access liquid chromatography-mass spectrometry

Characterization of recombinant protein purification fractions and final products by liquid chromatography-mass spectrometry (LC/MS) are requested more frequently each year. A protein open-access (OA) LC/MS system was developed in our laboratory to meet this demand. This paper compares the system that we originally implemented in our facilities in 2003 to the one now in use, and discusses, in more detail, recent enhancements that have improved its robustness, reliability, and data reporting capabilities. The system utilizes instruments equipped with reversed-phase chromatography and an orthogonal accelerated time-of-flight mass spectrometer fitted with an electrospray source. Sample analysis requests are accomplished using a simple form on a web-enabled laboratory information management system (LIMS). This distributed form is accessible from any intranet-connected company desktop computer. Automated data acquisition and processing are performed using a combination of in-house (OA-Self Service, OA-Monitor, and OA-Analysis Engine) and vendor-supplied programs (AutoLynx, and OpenLynx) located on acquisition computers and off-line processing workstations. Analysis results are then reported via the same web-based LIMS. Also presented are solutions to problems not addressed on commercially available, small-molecule OA-LC/MS systems. These include automated transforming of mass-to-charge (m/z) spectra to mass spectra and automated data interpretation that considers minor variants to the protein sequence-such as common post-translational modifications (PTMs). Currently, our protein OA-LC/MS platform runs on five LC/MS instruments located in three separate GlaxoSmithKline R&D sites in the US and UK. To date, more than 8000 protein OA-LC/MS samples have been analyzed. With these user friendly and highly automated OA systems in place, mass spectrometry plays a key role in assessing the quality of recombinant proteins, either produced at our facilities or bought from external sources, without dedicating extensive amounts of analyst resource.     

New software tools for visualization of analytical data

Efforts towards using advanced computer graphics for improved visualization of three-dimensional (3-D) secondary ion mass spectrometry (SIMS) data are described. The application of the Visualization Toolkit (vtk), a freely available C++ class library for 3-D graphics and visualization for both PC and Unix systems, is demonstrated. Various available algorithms are used to analyze and visualize features otherwise hidden within data. A selection of examples is presented to demonstrate the capabilities of data visualization.     

Principles and applications of a research-oriented gas chromatography—mass spectrometry data system

A research-oriented gas chromatography—mass spectrometry data system for a quadrupole mass spectrometer has been developed based on a centrally located departmental computer facility. An overview of the hardware and software system is presented, emphasizing the important aspects of on-line computer data acquisition and control and the design philosophy used in the development of the system. The application of the system is demonstrated by the g.c.—m.s. analysis of a mixture of four transition metal β-diketonates (Al, Cr, Rh, and Ru tris-1,1,1-trifluoro-pentane-2,4-dionate). This analysis involved vacuum gas chromatography with a support-coated open tubular column and detection of the eluent by chemical ionization mass spectrometry. The results demonstrate the data system capabilities and indicate the utility of the combined methodologies.     

A digital Compton suppression spectroscopy without gamma-ray coincidence-summing loss using list-mode multispectral data acquisition

The study demonstrates the advantages of an innovative list-mode multispectral data acquisition system that allows simultaneous creation of several different single, summed, coincident and anticoincident spectra with a single measurement. One of the consequences of list-mode data file offline processing is a reconstructed spectrum with Compton continuum suppression and without any full-energy peak efficiency deduction owing to true coincidence summing. The spectrometer is designed to read out analogue signal from preamplifier of gamma-ray detectors and to digitalize it using DGF/Pixie-4 software and card package (XIA LLC). This is realized by converting an Ortec Compton suppression data acquisition system into an all-digital spectrometer. Instead of using its timing electronic chain to determine the coincidence event, the analog signals from primary and guard detectors were connected directly into the Pixie-4 card for pulse height and time coincident measurement by individually logging and time stamping each electronic pulse. The data acquired in list-mode included coincidence and anticoincidence events consisting of records of energy and timestamp from primary and guard detectors. Every event was stored in a text file for offline processing and spectral reconstruction. A sophisticated computer simulation was also created with the goals of obtaining a better understanding of the experimental results and calculating efficiency.     

A computer system for the spectrometric analysis of high alloyed steel

Summary Experiences with a computer controlled analyser system for production control in a steel plant are reported. The analyser system consists of a direct reading vacuum spectrometer, a digital computer and a data transmission system. The computer system is responsible for the control of the spectrometer as well as for the transformation of measured values into element concentration values and their transmission into the plant internal teleprinter network. A great disadvantage of spectrometers is the fact that matrix effects occur. To solve the problems arising from that — especially in the case of analyses of an extended alloying program — either numerous special calibration curves for all the different types of alloyed steels can be established or one can use only one calibration curve and eliminate the matrix effects by calculation of the line coincidences and the third element influences. The combination of a spectrometer and a digital computer permits rapid determination of the chemical composition of samples by following the second procedure and makes the automatic transmission and documentation of data possible. The composition and working method of such an equipment is described, some selected examples for the used method of calibration are given. The principle of the digital computer program for the calculation of the chemical composition from measured intensity values is demonstrated, and the means of automatic transmission of results are shown. The main advantages of the system and also its limits are discussed.     

金属光电光谱仪软件、硬件改造

DV-6SN金属直读光电光谱仪经过十几年运转, 在硬件上出现老化问题,设备故障率不断,配件短缺,不能正常使用,软件不能适应检测数据信息化的要求。光谱仪经过软件、硬件的改造,在确保仪器分析精度不降低的前提下,通过改造升级旧光谱仪器的计算机控制系统、数据采集系统等,真空泵,部分有问题配件国产化改造,并配备新开发的光谱分析专用软件,能实现金属直读光谱仪正常运行,提高检测准确度,提高工作效率,旧光谱仪器获得新生,实现仪器的全面信息化数字化管理。     

Elemental 2D imaging of paintings with a mobile EDXRF system

Imaging techniques are now used commonly and intensively in cultural heritage object analysis. Nowadays, many different techniques in nature as well as many applications exist, where they can be applied. X-ray radiography and infrared reflectography as well as UV photography are some of the most applied techniques. The study of works of art usually requires these techniques to be non-invasive. Furthermore, they are frequently required to perform in situ analysis. A few years ago, our laboratory developed a mobile energy-dispersive X-ray fluorescence and UV–vis–NIR coupled spectrometer, especially designed for fieldwork studies, where all three techniques can be applied strictly at the same site of analysis. Recent developments on a new positioning system have now allowed us to perform 2D elemental mappings with our equipment, which is especially well adapted to painting analysis. The system control is carried out entirely through a laptop computer running a dedicated homemade software. The positioning is achieved by means of a CCD camera embedded in the system and controlled via a Wi-Fi connection through the computer. The data acquisition system, which is made through a homemade multichannel pulse height analyzer, being also managed via the software mentioned above, goes through an Ethernet connection. We will present here the new developments of the system and an example of in situ 2D elemental mapping applied on an anonymous oil painting on wood panel. The discovery of a hidden painting under this oil painting makes it a good choice for a first example of 2D large scan with a mobile instrument.     

An international intercomparison on “self-calibrated” alanine EPR dosimeters

The results, obtained by six independent electron paramagnetic resonance (EPR) laboratories, of the dose response coefficients (K_dr) of “self-calibrated” solid-state EPR dosimeters containing alanine as a radiation-sensitive material and Mn²⁺/MgO as an internal reference material, are reported. The intercomparison trial was divided into three steps. It started with the distribution of dosimeters among the participating EPR laboratories with the purpose of irradiating them with known doses of γ-rays and to estimate the K_dr. The percentage standard deviation (PSD) of the K_dr obtained at individual labs was in the range of 1.4–4.6%. The interlaboratory PSD of the K_dr was 8%, primarily pointing to variations in irradiation procedures and EPR spectrometer settings. Further investigations showed that the main source of the interlaboratory PSD is differences in the calibrations of irradiators and settings of EPR acquisition parameters. In order to provide reproducible estimates of the K_dr, low microwave power and modulation amplitude using a combination of sweep time and time constant that gives a distortion-free EPR spectrum should be utilized. In the third step following such a procedure, measuring the same irradiated alanine dosimeter at the respective laboratories, spectrometers (12 instruments of 6 different models and 3 producers) and 10 operators gave an interlaboratory PSD of 3.1%. In conclusion, EPR dosimetry using “self-calibrated” alanine dosimeters may be used as a secondary standard, although a careful calibration of the EPR spectrometer must be performed in order to further reduce the uncertainty.     

Analysis of light-induced conformational changes of Natronomonas pharaonis sensory rhodopsin II by time resolved electron paramagnetic resonance spectroscopy

The nature and kinetics of the conformational changes leading to the activated state of NpSRII/NpHtrII157 were investigated by time-resolved electron paramagnetic resonance (TR-EPR) spectroscopy in combination with site-directed spin labeling (SDSL) on a series of spin labeled mutants of NpSRII. A structural rearrangement of the cytoplasmic moiety of NpSRII upon light activation was detected (helices B, C, F and G). The increase in distance between helices C and F in the M-trapped state of the complex observed in one double mutant is in line with the notion that an outward movement of helix F occurs upon receptor activation. The data obtained from the NpSRII/NpHtrII157 complex reconstituted in purple membrane lipids are compared with those obtained from the X-ray structure of the late M-state of the complex which shows some discrepancies. The results are discussed in the context also of other biophysical and EPR experimental evidences.     

Biological Tissue Imaging with a Position and Time Sensitive Pixelated Detector

We demonstrate the capabilities of a highly parallel, active pixel detector for large-area, mass spectrometric imaging of biological tissue sections. A bare Timepix assembly (512?×?512 pixels) is combined with chevron microchannel plates on an ion microscope matrix-assisted laser desorption time-of-flight mass spectrometer (MALDI TOF-MS). The detector assembly registers position- and time-resolved images of multiple m/z species in every measurement frame. We prove the applicability of the detection system to biomolecular mass spectrometry imaging on biologically relevant samples by mass-resolved images from Timepix measurements of a peptide?Cgrid benchmark sample and mouse testis tissue slices. Mass-spectral and localization information of analytes at physiologic concentrations are measured in MALDI-TOF-MS imaging experiments. We show a high spatial resolution (pixel size down to 740?×?740?nm² on the sample surface) and a spatial resolving power of 6???m with a microscope mode laser field of view of 100?C335???m. Automated, large-area imaging is demonstrated and the Timepix?? potential for fast, large-area image acquisition is highlighted.     

Potentiometric stripping analysis automation

A semi-automatic system for potentiometric stripping analysis (PSA) based on the use of a potentiostat, a pH-meter with RS232C interface, and a personal computer is described. The appropriate software developed allows automatic control of the pre-electrolysis time, data acquisition and manual or automatic data treatment. Several elements can be determined at ng/ml level.