A Novel Spectrometer for Simultaneous Chemical Analyses

A novel spectrometer incorporating a multichannel detector for simultaneous multi-element atomic emission spectrometry (AES) is described. The spectrometer consists of a multi-bandpass optical filter comprised of a concave and a fiat grating in substractive mode, and a high resolution stage which utilizes an echelle grating and an one inch 1024-channel photodiode array as the detector. Characterization with respect to the spectral resolution, the spectral response, and the capability of multi-element detection demonstrated the systems's potential for simultaneous chemical analyses without moving any mechanical parts. To adjust the system for the analyses of different sets of elements, the corresponding mask is simply placed in position.     

Quantitative coherence analysis with an X-ray Talbot–Lau interferometer

Differential phase-contrast (DPC) X-ray imaging has been performed in the Talbot–Lau configuration, in which the X-ray source was a combination of an absorption grating and a laboratory X-ray generator. We report here quantitative analysis of partial coherence effects on the X-ray Talbot–Lau interferometer. Based on the visibility of the self-image, the well-known geometry condition is reproduced. It is shown that effects of partial coherence are determined by the opening ratio of the source grating, and that the effects are independent of the Talbot order and the type of the phase grating, a condition quite different from those in a Talbot interferometer. A possible explanation is discussed from the point of view of the effective spatial coherence length. Taking into account the available X-ray flux and experimental fluctuations, we present the optimum opening ratio. Furthermore, we mention that our results can also be successfully used to discuss the properties of a multiline X-ray source.     

Optimization of microwave‐assisted extraction followed by RP‐HPLC for the simultaneous determination of oleanolic acid and ursolic acid in the fruits of Chaenomeles sinensis

An optimized microwave‐assisted extraction (MAE) method and an efficient HPLC analysis method were developed for fast extraction and simultaneous determination of oleanolic acid and ursolic acid in the fruit of Chaenomeles sinensis. The open vessel MAE process was optimized by using a central composite experimental design. The optimal conditions identified were microwave power 600 W, temperature 52°C, solvent to material ratio 32 mL/g and extraction time 7 min. The results showed that MAE is a more rapid extraction method with higher yield and lower solvent consumption. The HPLC–photodiode array detection analysis method was validated to have good linearity, precision, reproduction and accuracy. Compared with conventional extraction and analysis methods, MAE–HPLC–photodiode array detection is a faster, convenient and appropriate method for determination of oleanolic acid and ursolic acid in the fruits of C. sinensis.     

Atomic emission analysis of human hair for the presence of trace elements

A procedure is developed for the atomic emission analysis of human hair with the preliminary acid mineralization of samples and excitation of spectra in samples of dry residues of hair mineralizate on the end face of a carbon electrode in an alternating current arch. Spectra were recorded on an MFS-8 spectrograph modernized with a MAES photodiode array. Using the developed analytical procedure, samples of hair were analyzed for the presence of Al, B, Ca, Cu, Mg, Mn, Fe, P, Pb, and Zn. The average concentrations and concentration ranges of these elements were calculated for samples collected from 42 donors. The results obtained were compared with the published data for other geographical regions.     

Experimental observation of line hyperfine structure with a plane grating spectrograph

For observing the hyperfine structure (HFS) of spectral lines it is required that the spectral bandwidth is smaller than or equal to both the physical widths of the HFS components and the wavelength distances between these components. The paper discusses how these conditions can be fulfilled for a 2.1-m plane grating spectrograph equipped with a 1200 grooves/mm grating. Using such a spectrograph observations were made of the HFS of lines emitted by hollow cathode lamps or an arc. Typical results for lines of Bi, Cu and In are reported. Wavelengths and relative intensities of HFS components are given.     

Adaptation of an existing algorithm for automated continuum correction in inductively coupled plasma-atomic emission spectrometry using a photodiode array detector

The use of a photodiode array as a multichannel detector for off-line continuum correction in inductively coupled plasma-atomic emission spectrometry(ICP-AES)is demonstrated. The photodiode array allows concurrent data acquisition of all reference wavelengths necessary for the calculation of the background. An existing background correction algorithm that selects reference channels by a statistical criterion is modified for use with the photodiode array. The influence of several parameters on the performance of the algorithm is investigated with spectra derived from the photodiode array and from a conventional photomultiplier based system. It is shown that with either system background correction can be performed completely automated and sample adapted.     

Design and characterization of a fiber optic-based fluorimeter

The design and preliminary charaterization of a novel fiber optic-based fluorimeter are reported. It includes a white light source, optical fibers for light transmission and an intensified photodiode array for detection. A bifurcated sensing configuration is used to transmit excitation and emission radiation to and from the analyte solution. Detection limits in the nanomolar range are reported for several test compounds.     

Investigation of the partially coherent effects in a 2D Talbot interferometer

The recent use of a one-dimensional (1D) X-ray Talbot interferometer has triggered great interest in X-ray differential phase contrast imaging. As an improved version of a 1D interferometer, the development of two-dimensional (2D) grating interferometry strongly stimulated applications of grating-based imaging. In the framework of Fresnel diffraction theory, we investigated the self-image of 2D-phase gratings under partially coherent illumination. The fringe visibility of the self-image has been analyzed as a function of the spatial coherence length. From the viewpoint of self-image visibility, it is possible to find the optimal 2D grid for 2D X-ray grating interferometer imaging. Numerical simulations have been also carried out for quantitative evaluation. Results, in good agreement with theoretical analysis, indicate the spatial coherence requirements of the radiation illuminating a 2D grating interferometer. Moreover, our results can be used to optimize performances of a 2D grating interferometer and for further theoretical and experimental research on grating-based imaging systems.     

CCD-1型平面光栅电弧直读发射光谱仪测定化探样品中铅锡钼铜银锌的方法研究

2017年三月我单位购进湖北地质中心实验室王鹤龄研发专利技术,将原来WP-1米平面光栅摄谱仪改造为CCD-1型平面光栅电弧直读发射光谱仪。CCD-1型平面光栅电弧直读发射光谱仪是对WP-1米平面光栅摄谱仪改造升级后,成为一款高性能全谱直读光谱仪。我们在原有CCD-1平面光栅电弧直读发射光谱仪测定硼锡银钼基础上,通过多次方法实验,研究出一次摄谱同时测定铅锡钼铜银锌六项元素的分析方法。六个元素测定的检出限Pb 1.56 Sn 0.42 Mo0.21 Cu 0.87Ag 0.012 Zn 7.95(RSD﹪ n=12)1.25﹪~7.43﹪,测定结果经验证准确度精密度检出限和合格率各项指标满足地质矿产实验室管理规范的要求。     

EVIDENCE FOR BRANCHING IN THE PHOTOCYCLE OF BACTERIORHODOPSIN AND CONCENTRATION CHANGES OF LATE INTERMEDIATE FORMS

Abstract— Flash photolysis transients of bacteriorhodopsin were recorded with a spectrograph -multielement photodiode array combination and the recordings were analyzed to determine the concentrations of bacteriorhodopsin intermediates "M" and "O" relative to the amount of "bR" cycling (pH 7.1,10–40°C). Estimated concentration time courses were simulated with solutions to two kinetic decay models which could account for photocycle temperature dependence. A unidirectional unbranched decay model overpredicts our estimated levels of [O(r)], whereas a model branched at the "M" intermediate describes each of the later intermediate levels well (with no evidence for an independent "N" form). Our results are consistent with "M" decay regulating the level and rates of change of [bR (t)] and (bR(f)]- and also suggest that two temperature-dependent pathways form "bR" from "M", one directly, and the other indirectly through "O".     

Simultaneous determination of seven main alkaloids of Chelidonium majus L. by ultra‐performance LC with photodiode‐array detection

A simple and rapid method for the simultaneous determination of seven isoquinoline alkaloids, protopine, chelidonine, coptisine, stylopine, sanguinarine, berberine, and chelerythrine, in Chelidonium majus L. (Ch. majus) samples by ultra‐performance LC method with photodiode array detection is described. The baseline separation of these compounds was performed with (A) acetonitrile–(B) ammonium acetate (10 mM, adjusted to pH 3.0 with acetic acid) as the mobile phase using a C18 RP column (2.1×100 mm, 1.7 μm). Optimized conditions resulted in excellent peak shapes. The seven alkaloids were completely separated within 20 min. Good linear behaviors (r≥0.9992) over the investigated concentration ranges were observed for all the analytes. Validation proved the repeatability of the method was good and recovery was satisfactory. The validated method was successfully applied for 20 batches of Ch. majus. These results demonstrated that the ultra‐performance LC photodiode array method proposed was very useful in the analysis and quality control of Ch. majus.     

WPP2型平面光栅摄谱仪常见故障及维护

简要介绍了WPP2型平面光栅摄谱仪常见故障现象,对故障产生的原因进行了分析,归纳总结了故障排除的方法与过程.     

Spectral source profiling with a photodiode array

A computer controlled Reticon photodiode array was used for source profiling by juxtapositioning the detector with the exit slit of a stigmatic monochromator, with the long axis of the array parallel to the slit. The sources to be studied were imaged on the monochromator entrance slit and the individual elements of the array detected light of a specific wavelength emitted from a different portion of the source as it appeared at the exit slit. The 512 array elements covered 12.5 mm of slit length. Larger or smaller portions of the source may be studied depending on the optics used to form the image on the entrance slit. Vertical profiles required only simple lenses for imaging. Profiles in horizontal direction were made quite simply by placing a Dove prism in the optical path to rotate the image 90°. Use of the system for elemental emission profiles for the nitrous oxide-acetylene flame and inductively coupled plasma is reported.     

Aperiodic x-ray multilayer mirrors and their application in plasma spectroscopy

We discuss the potentialities of aperiodic multilayer structures for the reflection of XUV radiation, including attooptical applications. Pilot samples of aperiodic normal-incidence broadband focusing multilayer mirrors are employed in a stigmatic transmission grating spectrograph with an operating range of 12.5–30 nm.This spectrograph was used to study (i) the XUV spectra arising from the charge exchange of laser-produced plasma ions with rare-gas (Xe, Kr, He) jet atoms, (ii) a debris-free Xe-jet plasma XUV source driven by Nd-laser pulses.     

An improved HPLC system for the analysis of photosynthetic pigments

Summary A high performance liquid chromatography system for the analysis of photosynthetic pigments is presented. The method employs an octadecylsilica stationary phase, a programmed quaternary mobile phase consisting of mixtures of methanol, acetonitrile, water and hexane, and a photodiode array detector. Carotenoids and chlorophylls are rapidly analysed in a single chromatographic separation. Thecis-trans isomers of most carotenoids are separated by this method.     

An LC Fingerprint Study of Poria cocos (Schw.) Wolf

The aim of the paper was to establish an efficient and accurate fingerprint method for the identification and quality control of Poria cocos (Schw.) Wolf. Methanol extracts of 43 samples of sclerotium and five samples of tegument were analysed by LC with photodiode array detection. Twenty common peaks were found and eleven of them were identified by mass spectrometry. The mutual pattern of 43 sclerotium samples was established and a Similarity Evaluation System and Principal Component Analysis were performed to analyze, differentiate and classify the samples. The method showed high precision, good repeatability and stability and all the peaks were well separated, so it can be used to assess the quality of P. cocos and to identify possible counterfeiting.

     

Multidimensional liquid chromatography for the determination of chiral coumarins and furocoumarins in Citrus essential oils

In this work the enantiomeric distribution of chiral coumarins (meranzin and epoxyaurapten), and furocoumarins (oxypeucedanin, byakangelicol, and epoxybergamottin) in different Citrus essential oils (lemon, lime, grapefruit, and bitter orange) was determined by means of a heart-cutting multidimensional-liquid chromatography (MD-LC) system, equipped with a microsilica column in the first dimension in a combination to a cellulosic-based chiral column used in the second dimension. The normal phase-liquid chromatography-liquid chromatography (NP-LC-LC) instrumentation was equipped with a photodiode array detector and a multiport valve as interface. For method optimization and the determination of absolute configuration, natural compounds were isolated and racemic mixture was synthesized. The NP-LC-LC/PDA (where PDA is photodiode array) method provided a good baseline separation of chiral coumarins (meranzin and epoxyaurapten) and furocoumarins (epoxybergamottin and byakangelicol) present in cold-pressed Citrus essential oils without any sample pretreatment. Results obtained showed that for all the chiral compounds present in Citrus essential oils analyzed, there is always a clear prevalence of one of the two enantiomers, and do not appear influenced by the different geographical origin of the oils.     

Simultaneous determination of seven lignans in Justicia procumbens by high performance liquid chromatography–photodiode array detection using relative response factors

A simple and sensitive HPLC coupled with photodiode array (HPLC–PDA) method was developed for simultaneous determination of seven lignans in Justicia procumbens using relative response factors (RRFs). The chromatographic separation was performed on a Shiseido Capcell Pak C₁₈ column (250 × 4.6 mm id, 5 μm), a gradient elution of acetonitrile/water, and a photodiode array detector. The column temperature was maintained at 35°C and the detection wavelength was set at 256 nm. Chinensinaphthol methyl ether was selected as the reference compound for calculating the relative response factors of the lignans. It has shown that the RRFs for lignans are quite similar at 256 nm of detection under different analytical conditions (different columns and HPLC instruments). Using RRFs, not every lignan is needed as a reference standard, making the method ideal for rapid, routine analysis, especially for those laboratories where lignans standards are not readily available. An economic and practicable HPLC method using RRFs was established for the determination of seven lignans in J. procumbens. This method not only can determine multiple indexes in traditional Chinese medicines (TCMs) simultaneously, but also resolve the problem of lacking of chemical standards. It will be a good quality evaluation method and pattern for TCMs.     

Versuche mit einem tiefgekühlten Zwillingsholkathoden-Interferometer—Spektrometer—II. Das optische System

The optical arrangement consists of a double beam imaging system an interferometer spectrometer attached to it. The two cathode spots are projected by the imaging system to the flip-flop mirror in the optical axis of the interferometer. One of the two cathode spots can be projected either to the slit of a spectroscope or to that of a spectrograph, respectively, for preliminary observation. For measuring the intensity ratios, neutral wedges are built into the imaging system. The principal component of the system is a piezo-electrically controlled Fabry—Perot interferometer spectrometer. The deparallelisation of the Fabry—Perot mirrors during the scanning, caused by the “fatigue” of the piezo-electrical system, was eliminated using suitable circuits. The good performance of the interferometer was checked by measuring of the finesse and resolution of selected spectral lines of different spectral lamps and the resonance radiation of a He---Ne gas laser. The optical set-up is suitable for general spectroscopic and spectrographic observations, for measuring radial intensity distributions, for obtaining high resolution spectra and for the determination of intensity ratios in the radiation of the twin hollow cathode source in the visible spectral range.     

Isocratic HPLC Separation of Scopoletin and Cis/Trans Isomers of Ferulic Acid as Well as Isoscopoletin and Cis/Trans Isomers of Isoferulic Acid

Abstract

Cis/trans isomers of ferulic and isoferulic acids and their corresponding coumarins, scopoletin and isoscopoletin, were separated by isocratic High Performance Liquid Chromatography using RP-8 (5 μm) as a stationary phase and aqueous methanol or aqueous acetonitrile as a mobile phase. The UV spectrum of cis-isoferulic acid was obtained by a photodiode array detector.