Fluorescence spectrometer-on-a-fluidic-chip

A chip-size spectrometer is realized by combining a linear variable band-pass filter with a CMOS camera. The filter converts the spectral information of the incident light into a spatially dependent signal that is analyzed by the camera. A fluidic platform is integrated onto the spectrometer for analyzing the fluorescence from moving objects. The target is continuously excited within an anti-resonant waveguide, and its fluorescence spectrum is recorded as the object traverses the detection area.     

Formation of the background component of the analytical signal in the long-wavelength region of X-ray fluorescence spectrum

Components of X-ray background in the long-wavelength spectral region of a crystal diffraction X-ray fluorescence spectrometer were calculated. The calculations took into account the bremsstrahlung radiation of free electrons, diffuse scattering and fluorescence of the crystal analyzer, and high-order reflections of the scattered radiation of the fluorescent sample by the crystal analyzer. The results of calculations were compared with the intensities of background samples measured in the region of the NaK _α fluorescence line on an SRM-25 wave X-ray spectrometer. The experimental background intensities (response function) well correlate with those found by the regression equation with calculated factors. The importance of particular processes in the formation of X-ray background was assessed.     

Compact fiber-optic fluorosensor employing light-emitting ultraviolet diodes as excitation sources

A compact fluorosensor using three different ultraviolet light-emission diodes as excitation sources for fiber-optic recording of fluorescence spectra from samples is described. A compact integrated spectrometer with linear array wavelength recording is used, yielding a spectral resolution of about 8 nm. In two system implementations ultraviolet light-emitting diodes at 300, 340 and 395 nm, or at 360, 385 and 410 nm were used as excitation sources with typical emission halfwidths of 12 nm, each combined with a matching long-path colored-glass filter automatically brought into the fluorescence light flow for suppression of reflected light. Spectra from measurements on vegetation, human skin tumors and a rare-earth ion-based thermographic phosphor were recorded to illustrate the system performance.     

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.     

Characterisation of optical detectors using high-accuracy instruments

The facilities of the Metrology Research Institute at the Helsinki University of Technology, and methods for characterisation of optical detectors for spectral radiant intensity and irradiance responsivity, are described. The instrumentation for such characterisations includes a reference spectrometer with a number of auxiliary set-ups, and equipment for the spectral irradiance measurements with a filter radiometer based on a trap detector. The methods of realising the spectral responsivity scales based on an absolute cryogenic radiometer in house are addressed. The procedures and results of characterisation of a multipoint measuring system of photosynthetically active radiation, by employing the available facilities, are briefly described. The absolute irradiance responsivity of the device is determined by using a photometric lamp, whose spectral irradiance has been measured with the filter radiometer. The combined standard uncertainty of this set of calibrations is 3.6% at the 1σ level. The uncertainty is caused almost completely by the multipoint measuring system.     

Development of quadrupole mass spectrometers using rapid prototyping technology

In this report, we present a prototype design of a quadrupole mass filter (QMF) with hyperbolic electrodes, fabricated at the University of Liverpool using digital light processing (DLP), a low-cost and lightweight 3D rapid prototyping (RP) technique. Experimental mass spectra are shown for H₂⁺, D₂⁺, and He⁺ ions to provide proof of principle that the DLP mass filter is working as a mass analyzer in the low-mass range (1 to 10 amu). The performance of the DLP QMF has also been investigated for individual spectral peaks. Numerical simulations of the instrument were performed by coupling CPO and Liverpool QMS-2 programs to model both the ion source and mass filter, respectively, and the instrument is shown to perform as predicted by theory. DLP thus allows miniaturization of mass spectrometers at low cost, using hyperbolic (or other) geometries of mass analyzer electrodes that provide optimal ion manipulation and resolution for a given application. The potential of using RP fabrication techniques for developing miniature and microscale mass analyzers is also discussed.     

Novel tandem quadrupole-acceleration-deceleration mass spectrometer for neutralization-reionization studies

A new tandem mass spectrometer of the quadrupole-acceleration lens-deceleration. lens-quadrupole (QADQ) configuration is described. The instrument is designed for neutralization-reionization studies and consists of a 2000-u quadrupole mass analyzer as MS-I, an acceleration electrostatic lens, a series of three differentially pumped collision cells, and an electrostatic deceleration lens, energy filter, and another 2000-u quadrupole mass analyzer as MS-II. The ion optical system achieves high total ion transmission for 5–9-keV ions. Unit mass resolution in neutralization-reionization mass spectra of aromatic compounds is demonstrated. Mass, kinetic energy, and linked scans at various levels of mass resolution and sensitivity are described.     

真空紫外灯单光子电离源飞行时间质谱仪的研制

研制了真空紫外灯单光子电离源飞行时间质谱仪(Vacuum ultraviolet single photon ionization time-offlight mass spectrometer,VUV-SPI-TOFMS),包括真空系统、毛细管进样系统、真空紫外灯电离源、垂直加速反射式飞行时间质量分析器和数据采集系统...     

Study on the structure and reactivity of COREX coal

COREX is the primary process in the current smelting reduction method. The process has strict coal quality standards. Combustion processes of coal used in the COREX operating system were analyzed using a synchronous thermogravimetric analyzer combined with a mass spectrometer. The microcosmic structure and macerals were observed by an electronic scanning microscope. The qualitative and quantitative determinations of oxygen functional groups, such as phenolic hydroxyl, carboxyl, carbonyl, and methoxy groups were detected by the Fourier Transform Infrared spectrometer (FT-IR) and through chemical analysis methods. In addition, the evolution of the chemical structure and transformation mechanism of organic oxygen functional groups during COREX coal combustion have been thoroughly investigated. This study proposes a new coal-requirement index system and coal blending method, which will increase the expansion of coal selection and decrease the overall usage of coal during COREX.     

Stray light effects in Zeeman atomic absorption spectrometry

A transverse Zeeman atomic absorption spectrometer has been modeled using a polychromatic, optical calculus simulation software program. The models were found to be realistic and greatly facilitated the study of the effects of various Zeeman spectrometer parameters and their interactions. The behavior of the Zeeman spectrometer calibration curves, in the presence of three different types of stray light, was modeled. From the initial results, it seems most likely that the major stray light source in real Zeeman experiments is due to polychromaticity of the light source, even when the source profile is relatively narrow in spectral bandwidth.     

ICP-AES法测定金合金首饰中铱元素分析谱线研究

采用电感藕合等离子体发射光谱法(ICP-AES)对金基体溶液中的Ir进行测试,分析讨论了国家标准GB/T21198.4-2007和美国热电Thermo IRIS Intrepid II型ICP光谱仪推荐的几种Ir谱线在金基体中的干扰问题.综合谱线强度、灵敏度、标准曲线相关系数、光强值、干扰谱线位置等因素,确定212.681 nm是该型ICP光谱仪测定金首饰中Ir元素的最佳谱线.     

Detection of large cluster ions by time-of-flight mass spectrometry with a conversion dynode

A linear time-of-flight mass spectrometer (TOF-MS) has been constructed to measure mass distribution of negatively-charged clusters formed in the hot filament diamond chemical vapor deposition (CVD) process and in the metal evaporation. A conversion dynode made of CsI was employed to enhance detection efficiency of the large clusters greater than 10 000 amu. An atomic peak from the tungsten evaporation was used for the mass calibration of the carbon clusters. The carbon clusters produced in the CVD diamond process was loosely bound so that they were easily fragmented during passage through accelerating electric fields. The mass distribution measured with the TOF-MS system showed much less abundance of large clusters than those measured previously with the energy analyzer and Wien filter.     

Analytical Characterization of a Solution Cathode Glow Discharge with an Interference Filter Wheel for Spectral Discrimination

Solution cathode glow discharge–atomic emission spectrometry (SCGD–AES) has attracted increasing attention in recent years in water and environmental analysis. In this article, the traditional spectrometer was replaced by an interference filter wheel for spectral discrimination using SCGD–AES. The aforementioned interference filters selected the spectral lines of Na, K, Ca, Li, Sr, Rb, and Cs. These spectral signals were transferred to weak currents using a photomultiplier tube and amplified by a picoammeter. The solution flow rate, discharge current and slit width were optimized individually. The analytical performance of SCGD coupled with an interference filter wheel was studied for atomic emission (SCGD–IFW–AES). The results show that the limits of detection for Na, K, Ca, Li, Sr, Rb, and Cs were 0.16, 0.36, 107, 0.53, 330, 1.93, and 13.58?µg/L, respectively. The relative standard deviations of the spectral intensities for the seven elements were 0.58, 0.94, 0.69, 0.70, 0.63, 0.67, and 0.65%, which indicated that the system operated stably. Matrix effect experiments were performed to study the effect of different concentrations of Na on the spectral intensities of K and Ca. Based on these measurements, the concentration of K in physiological saline was determined to be 0.534?mg/L by SCGD–IFW–AES.     

Direct and rapid analysis of ambient air and exhaled air via electrostatic precipitation of aerosols in an atomizer furnace and Zeeman spectrometry

Techniques that allow the elements present in the air to be determined in a simple and rapid manner are very attractive. Direct aerosol sampling techniques avoid the need to pretreat the filter via wet digestion in order to remove any sources of contamination, and they decrease the precipitation time significantly. Analyzers based on this technique can also determine the concentrations of elements in the air automatically in situ. This paper is concerned with the development of a novel analytical system that is based on electrostatically precipitating aerosols from the air into a graphite furnace. The equipment includes a Zeeman spectrometer with high frequency modulation polarization (MGA-915), and an electrostatic precipitation system incorporated into the analyzer. The high sensitivity of the system developed here means that it can be used to determine element concentrations in the air exhaled by humans, as well as those in ambient air.     

电感耦合等离子体原子发射光谱法中Kalman滤波法解析重叠谱线的研究

考察了Kalman滤波技术校正ICP-AES中谱线重叠干扰的潜力。以新息序列的平均平方和为评价函数优化扫描光谱的峰位, 消除扫描过程中可能产生的波长定位误差, 从而保证滤波结果的准确性, 并使实际检出限显著改善。在中等分辨率光谱仪和扫描步长为1.5pm的条件下, 滤波器能有效地分辨峰间距只有4.8pm且峰形基本相同的重叠线对。对峰间距为9.8pm的重叠线时, 当线背比低至0.05左右时仍能获得满意结果。连续背景用理论描述, 因而样品溶液和纯组分溶液的光谱扫描无需扣除溶剂空白。     

Analysis of heavy metal aerosols on filters by laser-induced plasma spectroscopy

Particulate heavy metals can lead to severe toxic and carcinogenic effects in humans when inhaled in higher concentrations. For the development of a quasi-continuous emission monitor based on automatic filter sampling on a filter band, laser-induced plasma spectroscopy (LIPS) was studied for analysis of heavy metal aerosols on quartz fiber filters. The system consists of a 19-inch laser and detector module connected to a miniaturized sensor head through fiber optics, allowing maximum flexibility of the set-up. Parameters for optimum time-resolved analysis, i.e. detection wavelength, timing and filter material, were established. The LIPS investigations were accompanied by a rigorous reference analysis based on total reflection X-ray fluorescence (TXRF) analysis. The detection limits for heavy metals (Cd, Ni, As, Co, Mn, Sb, Cr, Tl, Sn, V, Cu and Pb) on filters varied between 0.01 and approximately 0.91 μg cm⁻², corresponding to volume detection limits of 0.02–2.73 μg m⁻³. Analysis of filter samples from waste incineration demonstrated the potential of the LIPS approach. In combination with an echelle spectrometer, ambient samples from environmental monitoring could be characterized in much better detail, due to the improved detection limits and the superior spectral resolution, and spectral range of the echelle.     

Portable Analyzer for Rapid Analysis of Total Protein, Fat and Lactose Contents in Raw Milk Measured by Non-dispersive Short-wave Near-infrared Spectrometry

A novel portable analyzer for raw milk quality control during the material purchase at dairy plants was developed, by which the percentages(mass fraction) of main components including total protein, fat, and lactose of an unhomogenized milk sample could be determinated in 1 min with the help of non-dispersive short-wave near-infrared (NDSWNIR) spectrometry in a wavelength range from 600 nm to 1100 nm and multivariate calibration. The analyzer was designed with a single-beam optical system, which comprised a temperature control module, a multi-channel narrow-band light source(16 wavelengths), a glass absorption cell with 15 mm sample thickness, a silicon photodiode detector, several compound lenses and a recorder module. A total of 80 raw milk samples were collected at a dairy farm twice a month for 4 months. The samples were scanned with a common UV-Vis-NIR spectrometer and analyzed according to China GB standard methods. The uninformative variables elimination(UVE) method was carried out on the spectrum data and the percentages of main components of all the samples to choose the peak emitting wavelength of each channel of the light source. Another 90 raw milk samples were collected from the same dairy farm thrice a month for 3 months. The samples were analyzed according to China GB standard methods and with the proposed analyzer. The percentages of the main components and the NDSWNIR absorption data of the samples were used for the construction and validation of the multivariate calibration model with partial least squares(PLS) method. The root-mean-square errors of prediction(RMSEP) of total protein, fat and lactose were 0.201, 0.172 and 0.247 and the coefficients of correlation(R) were 0.932, 0.981 and 0.933, respectively.     

Development of a heterogeneous catalytic cracking reactor utilizing online mass spectrometry analysis

A laboratory system has been designed, constructed, and validated that reduces the complexity, time required, and data variability associated with catalytic microreactors that require post reaction steps prior to product analysis. In this work, a Varian (Walnut Creek, CA, USA) 3600 GC (gas chromatography) system coupled with a Saturn quadrupole ion trap mass spectrometer was used to perform mass spectral analysis in real-time catalytic cracking reactions. As this was an integrated reactor/analyzer, the GC column was exposed to temperatures beyond the degradation point of the column, and so selective ion storage RF waveform was used to remove the siloxane masses from the spectra. This produced lower detection limits and full scan data for identification. Mass/charge segmentation of the mass spectrometer allowed the complete product identification for electron impact spectra. Hexane was reacted over H-ZSM-5 catalyst for instrument validation. This produced a series of alkanes, alkenes, and aromatics with distributions consistent with that reported for the cracking of hexane.     

Enhanced Static Modulated Fourier Transform Spectrometer for Fast Approximation in Field Application

We discuss the data sampling frequency, the spectral resolution, and the limit for non-aliasing in the static modulated Fourier transform spectrometer based on a modified Sagnac interferometer. The measurement was performed in a very short 4 ms, which is applicable for real time field operation. The improved spectrometer characteristics were used to investigate the spectral properties of an InGaAs light emitting diode. In addition, The measured spectral peak was shifted from 6420 cm⁻¹ to 6365 cm⁻¹, as the temperature increased from 25 °C to 40 °C, when the operating current is fixed to be 0.55 A. As the applied current increased from 0.30 A to 0.55 A at room temperature, the spectral width was broadened from 316 cm⁻¹ to 384 cm⁻¹. Compared to the conventional Fourier transform spectrometer, the measured spectral width by the static modulated Fourier transform spectrometer showed a deviation less than 10%, and the spectral peak shift according to the temperature rise showed a difference within 2%.