毛细管电泳光学检测器的进展

对毛细管电泳的光学检测器作了简要评述。根据所采用的检测原理。光源检测器可分为紫外检测器，激光诱导荧光检测器、化学肆光检测器、荷耦合器件检测器、折射指数检测器等许多种类，具有简单方便、使用广泛，信息量较大等特点，是一类有良好诉检测器。     

Comparison of different detectors for amino acid analysis

Summary Three different detectors for gas chromatography are compared in respect to sensitivity and selectivity: the flame-ionization detector, the nitrogen-selective alkali-flame ionization detector and the electron-capture detector. Their suitability for amino acid analysis is discussed, especially concerning sensitivity and linearity of detection. The nitrogen-selective detector proved to be most suitable both in respect to sensitivity and selectivity. The detection limit is in the range of less than 1 pg using the nitrogen-selective detector, about 1 – 2 pg with the electron-capture detector and about 5 –15 pg using the flame-ionization detector.

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Vergleich verschiedener Detektoren für die Analyse von Aminosäuren

     

The high-performance liquid chromatography and detection of phospholipids and triglycerides: Part 2. Comparison of an ultraviolet absorption and post-column reactor detector

A liquid chromatographic ultraviolet absorption detector (at 195 nm) and a novel postcolumn reactor detector are compared for use in the detection of triglyceride and phospholipid molecular species. The detection limit for the u.v. detector depends on the degree of unsaturation of the lipid sample (3 × 10^-6–2 × 10^-8 M in the detector cell for 0–3 double bonds per acyl group). The post-column reactor detector is responsive to equivalents of lipid and has detection limits of 5 × 10^-7 M for triglycerides and 2 × 10^-6 M for phospholipids. The log u.v./post-column reactor detector response ratios are linearly related to the log of the degree of unsaturation of the lipid, indicating the usefulness of both detectors for quantifying triglycerides and phospholipids.     

Optimization of an electrolytic conductivity detector for determination of toxic nitrogen-containing food contaminants separated by open tubular column gas chromatography

The combination of open tubular column gas chromatography with electrolytic conductivity detection has been evaluated for the determination of nitrogen-containing pesticide residues in food extracts. Optimization of the column position at the column-detector interface was crucial to the successful operation of the detector. The signal-to-noise ratio and response stability of the detector are greatly influenced by the composition of the electrolyte solvent. Large volume splitless injections using retention gaps and optimized detector operating conditions enabled pesticide residues in food extracts to be determined at sub parts-per-million levels. Although the electrolytic conductivity detector is less sensitive than the thermionic ionization detector, its greater nitrogen selectivity can he crucial to the determination of nitrogen-containing contaminants in food extracts, particularly in complex mixtures where phosphorus-containing contaminants or matrix compounds are also present.     

二元复杂共混体系组成的SEC-LS分析

提供了一种利用体积排阻色谱-光散射(SEC-LS)联用技术来解决二元复杂共混体系组成的定量分析问题.基于体积排除色谱的绝对定量化原则,首先从理论上分析了共混物的光散射响应因子与组成呈线性关系.通过分析六组复杂共混体系的光散射响应因子与组成的关系,验证了该线性关系确实存在.进而利用该线性关系计算了共混体系的组成.在某些共混体系中,通过光散射响应因子得出的组成比利用示差法得出的组成更加接近原料组成.通过分析这两种方法产生误差的来源,阐述了产生该现象的原因.     

A simple mathematical method to determine the efficiencies of log-conical detectors

A new type of photon detector, log-conical, is proposed. The average path length traveled by an incident photon of arbitrary energy as well as the geometrical solid angle are calculated in a mathematical expression to determine the efficiencies of this detector for an arbitrarily positioned isotropic radiating point source. The off-axis effect of the source position was analyzed to demonstrate the powerful capability of the proposed method. The results are compared with those obtained using a standard 3″×3″ cylindrical detector of the same volume in order to show the enhanced efficiency of the log-conical detector.     

Application of a simple photoionization detector for non-dispersive atomic spectrometry in the vacuum ultraviolet region

The construction and operation of a simple, solar-blind photoionization detector which responds to incident radiation between 125 and 140 nm is described. The detector, the response characteristics of which are controlled by the ionization potential of the ethylamine filler gas and the calcium fluoride window employed, is shown to provide for efficient detection of atomic line emission from carbon, oxygen and chlorine in this wavelength region. The spectral sources employed for non-dispersive work with this detector are a microwave-excited argon plasma and a demountable hollow-cathode lamp.     

High-performance liquid chromatography of nitrophenols with a swept-potential electrochemical detector

The advantages of a swept-potential electrochemical detector are demostrated by application to the high-performance liquid chromatography (h.p.l.c.) of nitrophenols. The primary advantage of the detector is that an additional dimension of information is obtained which can be help identify a chormatographic peak and help to resolve overlapping peaks. The detector retains the selectivity of a differential-pulse detector and yet is general enough to minimize the time for development of new procedures and to detect true methanol-acetate buffer mobile phases. Selectivity factors of the mononitrophenols are independent of the composition of the mobile phase from pH 3.25 to 6.00 and from 40 to 55% methanol. The selectivity factors of dinitrophenols are highly dependent on pH. Limits of detection depend on many parameters but are approximately 1 ng injected for the nitrophenols.     

Possible effect of source backing on the backscatter peak in gamma spectra

Backscattering peak is one of the main features of the pulse height spectrum from a gamma ray detector. This arises mainly from materials outside the detector like source backing, photo multiplier tube housing, shielding etc. We have studied the effect of source backing on the relative importance of the back scattered peak for a NaI(I) scintillation detector. Gamma energies in the range from 60 to 1333 keV have been used. The measurements have been carried out for various backing thicknesses and differing source to detector distances. The details of the measurements and the results are presented.     

Increasing the reliability of the identification by high-performance liquid chromatography by means of selective and/or sensitive detection

An approach for quantitative assessment of the reliability of identification at high-performance liquid chromatography is proposed. The quantitative assessment of identification is useful for determination of selectivity at validation of the analytical methods. Chromatograms and spectra of the analytes are presented as maps in which characteristics as retention times, detector's signals, maxima and minima and another characteristics of spectra are used for identification. A formula for quantitative determination of the contribution of these characteristics on the reliability of identification is given. Using the more selective diode array detector than the convenient UV detector increases the reliability by several orders. A similar result was obtained when the UV detector was replaced with the more sensitive and selective fluorescence detector. Despite of the small contribution of the separation to the reliability its influence is very important for distinguishing of isomers because their spectra are identical.     

毛细管电泳多道电化学检测器的研制及其应用

报道了毛细管电泳多道电化学检测器的研制及其应用，安培检测器和电导检测器并联在同一毛细管电泳检测系统中，在同一缓冲体系，同一工作电极下对同一复杂的分析体系同时进行电导和安培检测；整个装置综合了电导检测和安培检测两种检测器的优点，性能优良，造价低廉，对实际样品的检测取得了令人满意的结果。     

用于天文成像探测的IRFPA性能参数测试

天体的红外成像探测在天文学领域中有其特殊和重要的作用,高性能红外探测器是红外天文观测的关键器件,因此红外焦平面阵列探测器性能参数的测试评价对于红外天文观测具有非常重要的意义。针对天文应用的特殊性,通过分析红外焦平面阵列(Infrared focal plane array,IRFPA)探测器的特点,给出了增益、读出噪声、线性和暗流等性能参数的测试原理和方法,建立了测试平台,该测试平台可实现1~14μm波长范围的IRFPA探测器性能参数测试;完成了一台采用国产3~5μm HgCdTe芯片研制的IRFPA探测器性能参数的测试。测试结果表明,该IRFPA探测器的线性度非常好,可以达到99.9%以上,但读出噪声和暗电流较大,与国外为天文观测研制的高性能探测器相比尚有很大的差距。     

Compton suppression system at Penn State Radiation Science and Engineering Center

A Compton suppression system is used to reduce the contribution of scattered gamma-rays that originate within the HPGe detector to the gamma-ray spectrum. The HPGe detector is surrounded by an assembly of guard detectors, usually NaI(T1). The HPGe and NaI(T1) detectors are operated in anti-coincidence mode. The NaI(T1) guard detector detects the photons that Compton scatter within, and subsequently escape from the HPGe detector. Since these photons are correlated with the partial energy deposition within the detector, much of the resulting Compton continuum can be subtracted from the spectrum reducing the unwanted background in gamma-ray spectra. A commercially available Compton suppression spectrometer (CSS) was purchased from Canberra Industries and tested at the Radiation Science and Engineering Center at Penn State University. The PSU-CSS includes a reverse bias HPGe detector, four annulus NaI(T1) detectors, a NaI(T1) plug detector, detector shields, data acquisition electronics, and a data processing computer. The HPGe detector is n-type with 54% relative efficiency. The guard detectors form an annulus with 9-inch diameter and 9-inch height, and have a plug detector that goes into/out of the annulus with the help of a special lift apparatus to raise/lower. The detector assembly is placed in a shielding cave. State-of-the-art electronics and software are used. The system was tested using standard sources, neutron activated NIST SRM sample and Dendrochronologically Dated Tree Ring samples. The PSU-CSS dramatically improved the peak-to-Compton ratio, up to 1000:1 for the ¹³⁷Cs source.     

Rapid and sensitive gas chromatographic determination of diacetylmorphine and its metabolite monoacetylmorphine in blood using a nitrogen detector.

A quantitative gas chromatographic method for the determination of plasma concentrations of diacetylmorphine and its metabolite monacetylmorphine using an alkali flane detector (nitrogen detector) is described. Plasma samples (pH 9.0) containing ethylmorphine acetate as internal standard are extracted with benzene. The dried benzene extracts are analysed as their corresponding acetylated derivatives following treatment with trifluoroacetic anhydride-benzent (1:5). The nitrogen detector permits quantitation of narcotic levels down to 100ng/ml with detection as low as 20 ng/ml. The higher sensitivity and selectivity of the nitrogen detector are compared to those obtained in flame ionization detection. Species differences in the rate of conversion of diacetylmorphine to monacetylmorphine in vitro in blood are also presented.     

Special aspects of detection methodology in nonaqueous capillary electrophoresis

Over the recent years considerable efforts have been directed to the design of powerful detector arrangements for capillary electrophoresis (CE). The analytical characteristics of the detector have a great influence on the overall analytical performance of CE investigations. The major detection methods in CE, such as UV-Vis absorbance, fluorescence, mass spectrometry and electrochemical detection, have successfully been adapted also to nonaqueous capillary electrophoresis (NACE). However, the different properties of organic solvent systems require some modification of detector concepts and design compared to aqueous CE. The advances of detector development and application in NACE are reported and discussed with emphasis on methodical aspects.     

Monte Carlo generated spectra for QA/QC of automated NAA routine

A quality check for an automated system of analyzing large sets of neutron activated samples has been developed. Activated samples are counted with an HPGe detector, in conjunction with an automated sample changer and spectral analysis tools, controlled by the Canberra GENIE 2K and REXX software. After each sample is acquired and analyzed, a Microsoft Visual Basic program imports the results into a template Microsoft Excel file where the final concentrations, uncertainties, and detection limits are determined. Standard reference materials are included in each set of 40 samples as a standard quality assurance/quality control (QA/QC) test. A select group of sample spectra are also visually reviewed to check the peak fitting routines. A reference spectrum was generated in MCNP 4c2 using an F8, pulse-height, tally with a detector model of the actual detector used in counting. The detector model matches the detector resolution, energy calibration, and counting geometry. The generated spectrum also contained a radioisotope matrix that was similar to what was expected in the samples. This spectrum can then be put through the automated system and analyzed along with the other samples. The automated results are then compared to expected results for QA/QC assurance.     

A nickel oxide amperometric detector in the chromatographic separation of amino acids

Reverse-phase ion-pair chromatography with a nickel oxide amperometric detector is evaluated for separation and detection of several amino acids. A simple T-junction allows post-column mixing of detector electrolyte. Mixer and detector dimensions are shown to contribute negligibly to band spreading. Picomole amounts of some amino acids can be detected. The system is evaluated for determination of amino acids in hydrolyzed bovine A-chain insulin and urine samples.     

Characterization of responses to injection of microliter samples and to peak-shaped input signals for inductively-coupled plasma/atomic emission spectrometry

The use of inductively-coupled plasma/atomic emission spectrometry for dynamic measurements, e.g., as a detector in high-performance liquid chromatography or flow injection analysis with introduction of microliter samples, requires specification of the dynamic properties of the detector. A model of the transfer function in ICP/AES, based on the Γ-distribution, is described. The two important parameters of the model are easily evaluated in practice, so that the response of an ICP/AES detector to introduction of microliter samples and the influence on peak-shaped injections are readily calculated.     

高效毛细管电泳紫外检测器光路的特殊性及其优化

紫外检测器用于高效毛细管电泳（ＨＰＣＥ）的主要难题在光路中,ＨＰＣＥ中熔融石英毛细管（内径通常在５０μｍ左右）直接放在光路中,一方面光程短,另一方面,光在透镜及毛细管界面上的折射与反射使光程常比毛细管内径短,甚至可能绕过毛细管内腔［１,２］．本文编制...     

Simultaneous acquisition of X-ray spectra using a multi-wire, position-sensitive gas flow detector

A multi-wire, gas-filled position-sensitive detector has been developed for the simultaneous recording of wavelength-dispersed X-ray signals that enables X-ray fluorescence spectrometry with a limited multi-element capability in the low Z element range. Details of the modular construction of the detector are given. The detector performance was characterized using Al–K radiation and a variable slit system. The detector has been applied in a laboratory spectrometer equipped with an electron source and a double multilayer mirror device as the wavelength-dispersing element. Spectra from Al and Si obtained in the simultaneous acquisition mode show good agreement with calculations performed using a ray-tracing model.