Laser-induced luminescence of barite after thermal treatment

The photoluminescence (PL) of barite is a noncharacteristic property and cannot be used for the investigation of its structure. After thermal treatment of barite at 600°C several luminescent centers were observed, providing information about different impurities. UO ₂ ²⁺ was determined from the vibrational structure and the long decay time of the luminescence band. Two different types of uranyl were detected, thin films of uranyl mineral (most probably, reserfordin) and a solid solution of uranyl ion in barite crystal. Characteristic green luminescence of UO ₂ ²⁺ may be used as indicative feature for the prospecting of uranium deposits and for the sorting of barite ores with the aim of cleaning from harmful U impurities. Eu²⁺ was determined from the spectral position, the half-width and the characteristic decay time of the luminescence band. Mn²⁺ and Ag⁺ were determined by comparing luminescence bands spectral parameters to those of synthesized BaSO₄−Mn and BaSO₄−Ag. Fe³⁺ or Mn⁴⁺ were determined from the spectral-kinetic parameters of the luminescence bands. Dedicated to Professor Lisa Heller-Kallai on the occasion of her 65^th birthday     

Laser-induced breakdown spectroscopy: Time-resolved spectrochemical applications

We have added time resolution to laser-induced breakdown spectroscopy in two forms, by gating an optical multichannel analyzer (OMA) and by time-resolving the output of a photomultiplier with a boxcar amplifier. Spectra were obtained for temporal segments of 25 to 100 ns, from 25 ns to 50 µs after initiation of the breakdown. OMA spectra of oxygen illustrate the power of this technique for survey purposes. The photomultiplier-boxcar arrangement was used to detect phosphorus atoms from diisopropylmethyl phosphonate in air, and also to detect chlorine in air, both in real time. In the former experiments we detected 690 ppm (w/w) of phosphorus and project a limit of detection with our current apparatus of 15 ppm (w/w). For chlorine, we observed signal from 120 ppm (w/w) and project a limit of detection of 60 ppm (w/w).     

激光诱导荧光检测微流控芯片生化分析仪的研制

研制出一种集激光诱导荧光检测、微流控芯片电泳及控制系统于一体的生化分析仪。分析仪内采用可重复使用的玻璃基质微流控芯片,利用销式固定技术实现芯片的精确定位,定位精度达到±2μm。以四触点高电压系统控制芯片上的进样和电泳分离操作。激光诱导荧光检测系统采用正交光路模式,对Cy5染料的检出限达到1.0×10-10mol/L(S/N=3)。以羟乙基纤维素为筛分介质,初步进行了ΦΧ174-HaeШdigest DNAmarker限制性片段的毛细管电泳分离。     

532nm激光诱导荧光毛细管阵列电泳仪的研制

基于共聚焦激光诱导荧光检测技术,研制了一台旋转扫描高效毛细管阵列电泳装置。以波长为532nm的半导体二极管激光器作为激发光源,多根毛细管阵列采用圆形布局,微型高速直流电机带动旋转反射镜进行激光扫描,加快了数据采集的速度;采用旋转编码器实现了毛细管的定位与位置读出,并触发数据采集系统进行荧光信号采集。以罗丹明6G和罗丹明B为分析样品,考察了16通道毛细管阵列电泳仪的基本性能。     

Basic investigations for laser microanalysis: II. Laser-induced fluorescence in laser-produced sample plumes

Laser-induced fluorescence in laser-ablated standard steel samples was measured, in order to study the atomization and propagation properties of the plasma plume and the analytical figures of merit of the method. As an example, measurements were performed exciting silicon, chromium or boron atoms by pulsed dye laser radiation.     

532 nm激光诱导荧光毛细管阵列电泳仪的研制

基于共聚焦激光诱导荧光检测技术,研制了一台旋转扫描高效毛细管阵列电泳装置.以波长为532nm的半导体二极管激光器作为激发光源,多根毛细管阵列采用圆形布局,微型高速直流电机带动旋转反射镜进行激光扫描,加快了数据采集的速度;采用旋转编码器实现了毛细管的定位与位置读出,并触发数据采集系统进行荧光信号采集.以罗丹明6G和罗丹明B为分析样品,考察了16通道毛细管阵列电泳仪的基本性能.     

Laser-induced fluorescence in a furnace: A viable approach to absolute analysis?

The possibility of performing absolute analysis by laser-induced atomic fluorescence in a graphite tube atomizer is discussed. At the sensitivities which are typical of these measurements, i.e., at absolute levels of the order of femtograms, it is argued that the lack of certified reference materials and the practical limitations in preparing standard solutions constitute the major incentives to the development of absolute analysis. The various theoretical and experimental parameters needed in the procedure of converting a measured fluorescence signal, e.g., a voltage, into the corresponding number of emitting atoms are discussed and evaluated with respect to a typical determination of a toxic element like thallium.     

毛细管电泳分离-激光诱导荧光检测生物胺

采用新合成的6-氧-[(1-琥珀酰亚胺)氧酰甲基]-荧光素乙酯(SOFE)作为柱前衍生试剂,毛细管电泳分离-激光诱导荧光检测了乙醇胺(EOA)、组胺(His)、甲胺(MA)、乙胺(EA)、酪胺(TYR)及苯乙胺(PEA)6种生物胺。在硼酸-硼砂缓冲溶液(pH8.5)中,室温(25℃)下衍生10min。用pH8.5的含25mmol/LSDS15%(V/V)乙腈的40mmol/L硼酸盐溶液作为电泳缓冲溶液,6种衍生物在15min内完全分离,检出限在2.5×10-11～8×10-11mol/L之间。该方法应用于酱油中生物胺的测定,结果令人满意。     

Laser-induced breakdown spectroscopy: Time-integrated applications

Spectral analysis of the plasma produced by laser-induced breakdown was demonstrated to be an effective real-time technique for the detection of atomic constituents in gases and gas-entrained particulates. The time-integrated technique, LIBS (laser-induced breakdown spectroscopy), was applied to the detection of sodium and potassium in a coal gasifier product stream, of airborne beryllium, and of phosphorus, sulfur, and chlorine in various organic molecules. In a companion paper (following) the time-resolved technique will be discussed.     

Laser-induced thin film formation from a gaseous mixture of trimethylsilylacetylene and methyl acrylate

Under irradiation with N₂ laser light, gaseous trimethylsilylacetylene (TMeSiA) and a gaseous mixture of TMeSiA and methyl acrylate (MA) produced thin films on an incident optical quartz window of an irradiation vessel. The product yield decreased with increasing partial pressure of TMeSiA. From the analysis of FT-IR spectra and X-ray photoelectron spectra of the deposited films, it was shown that Si---C bond of TMeSiA was cleaved by a two-photon absorption of N₂ laser light to produce trimethylsilyl radical and the silanes, R(CH₃)Si=CH₂ (R: H₃C---, CHC---). Trimethylsilyl radical reacted with MA at C=C and C=O bonds to produce Si---C and Si---O bonds in the film deposited from the gaseous mixture. The silanes were polymerized in each other to produce a thin film from pure TMeSiA vapor. Under irradiation with a medium pressure mercury lamp, a gaseous mixture of TMeSiA and MA produced aerosol particles in addition to the film. Polymeric species of TMeSiA was more involved in the aerosol particles rather than in the film, suggesting that collisionally induced chemical reaction takes place efficiently between excited MA and TMeSiA molecules.     

痕量糖-8-氨基芘-1,3,6-三磺酸衍生物的毛细管电泳-激光诱导荧光分析

以芘为原料经磺化、氨化合成了８－氨基芘－１,３,６－三磺酸钠盐（ＡＰＴＳ）,建立了相应的纯化方法,考察了多种条件对还原单糖衍生效率的影响,研究单糖及葡聚糖水解寡糖－ＡＰＴＳ衍生物的毛细管电泳－激光诱导荧光分离与检测,单糖的检测限在ａｍｏｌ（１０＾－１８）水平。     

Coarse Metal Powder-Assisted pulsed CO2 Laser-induced Breakdown Spectroscopy for the Direct Determination of Heavy Metals in Soil

A novel method of laser-induced plasma spectroscopy utilizing a pulsed transversely excited atmospheric CO₂ laser has been developed for the high-sensitivity determination of heavy metals in soil. A coarse metal powder was used to trap the soil and to assist with plasma generation. When the CO₂ laser (10.6?µm, 1.5?J, 200?ns) was irradiated on the metal and soil powder, a high-temperature and long-lifetime luminous plasma was induced. Fine particles of soil were dissociated and were excited in the plasma region. The method was used for the rapid determination of Cr, Pb, and Hg in loam. The limits of detection for Cr, Pb, and Hg were approximately 0.8, 15, and 0.7?mg/kg, respectively.     

Laser-induced Graphene in Facts,Numbers, and Notes in View of Electroanalytical Applications: A Review

In this review, laser-induced graphene (LIG) -based electrodes are discussed by covering such essential areas, as a characterization of LIG material properties necessary for electroanalysis, including data on LIG sheet resistance, wettability, spatial resolution, electrochemical characteristics, as well as correlations of “process” - “properties” - “electroanalytical characteristics”of LIG-electrodes. Moreover, typical and innovative LIG-based electrodes designs for electroanalytical applications, including combined multi-analyte multimodal wearable sensors, interdigitated electrodes, are shown. The essential data related to LIG in electroanalysis are summarized in tables. The authors also discussed recent LIG-based electroanalytical applications. Close attention has been paid to LIG glucose sensors and biosensors.     

Determination of Amino Acids in an Individual Erythrocyteby Capillary Electrophoresis with Intracellular FITC-derivatization and Laser-induced Fluorescence Detection

A novel approach for analysis of amino acids in individual erythrocytes was established.In this method, the derivatization reagent was in~oduced into the living cells by electroporation.After derivatization, the amino acids in a single cell were determined by capillary electrophoresis with laser-induced fluorescence detection.     

Laser-induced breakdown spectroscopy of archaeological findings with calibration-free inverse method: Comparison with classical laser-induced breakdown spectroscopy and conventional techniques

A modified version of the calibration-free (CF) method was applied to the analysis of a set of archaeological brooches made of various copper-based alloys and coming from the archaeological site of Egnatia (Apulia, Southern Italy). The developed methodology consists in determining the plasma temperature by reversing the set of equations employed in the usual CF algorithm, and it is thus referred to as “inverse method”. The plasma temperature is determined for one certified standard, by using its known elemental composition as an input data, and then applied to the set of unknown samples to evaluate their composition in a CF mode. The feasibility of such an approach is demonstrated by comparing the results obtained with classical LIBS (drawing calibration lines with a series of matrix-matched certified standards) and with independent measurements performed with a conventional technique (LA-ICP-MS).     

毛细管电泳-激光诱导荧光测定大鼠血浆内痕量氨基酸类神经递质

用菁色素衍生物 (Cy5 )作为荧光衍生试剂 ,毛细管电泳结合激光诱导荧光分离测定痕量氨基酸类神经递质甘氨酸和谷氨酸。讨论了Cy5浓度 ,缓冲液浓度 ,pH值和反应时间等实验条件对衍生和分离的影响。衍生物的荧光强度和氨基酸的浓度在 7.5× 1 0 - 8～ 3 .5× 1 0 - 6 mol L范围内呈现良好的线性 ,线性相关系数均达到 0 .999。甘氨酸和谷氨酸的最低检出限浓度分别为 3 .3× 1 0 - 9mol L和 1 .0×1 0 - 9mol L。测定了大鼠血浆中甘氨酸和谷氨酸的浓度 ,分别为 (62± 1 4 )× 1 0 - 6 mol L和 (1 9± 2 )× 1 0 - 6 mol L。与其它氨基标记荧光试剂 ,如FITC和TRITC相比 ,Cy5与一级胺反应时间短 ,选择性高     

Enzyme promiscuity: first protein-catalyzed Morita-Baylis-Hillman reaction

The Morita-Baylis-Hillman reaction of cyclohexenone and p-nitro benzaldehyde is catalyzed by carrier proteins such as serum albumins or enzymes such as certain lipases, conversion of up to 35% and enantioselectivities of up to 19% being observed.     

A comparison between ethylene dimerization and Diels-Alder reaction

The reaction pathways for the two reactions 2C₂H₄C₄H₈ and C₂H₄+C₄H₆ C₆H₁₀ were investigated. The transition state geometries and activation energies were determined with the SINDO method and compared. Both reactions were found concerted with different significance of diradical character at the transition state. Whereas the ethylene dimerization showed that a diradical will be encountered along the reaction pathway, we did not find one in the Diels-Alder reaction.     

毛细管区带电泳激光诱导荧光间接检测环腺苷单磷酸和环鸟苷单磷酸

研究了影响毛细管区带电泳激光诱导荧光间接检测环腺苷单磷酸和环鸟苷单磷酸的实验条件.cAMP和cGMP的线性范围分别为30～500mg/L和15～500mg/L,其最低检测限分别为9.0mg/L和0.5mg/L;当浓度为125mg/L时,cAMP和cGMP峰面积的RSD为4.45%和6.21%(n=4);其迁移时间的日间RSD分别为2.92%和2.04%(n=5)