大气压电解液阴极辉光放电发射光谱技术的研究进展及应用

近十多年来,大气压电解液阴极辉光放电系统在原子光谱分析中作为一种新兴的检测工具而备受关注。大气压电解液阴极辉光放电发射光谱技术兼具了光谱测量的稳定性、分析元素选择性和传感器测量方便、简洁性等优点。本文综述了基于等离子体的大气压电解液阴极辉光放电发射光谱技术的机理研究、仪器构建及改进和最新应用研究,并总结了该技术的优势及存在的问题,展望了其应用前景。     

液相辉光放电原子发射光谱法测定溶液中Cd的方法研究

通过改进放电装置,建立了一种新的液相辉光放电原子发射光谱(LGD-AES)测量溶液中Cd元素的方法。探索了放电电压和Cd浓度对放电稳定性、光谱信号强度、测定灵敏度和检出限的影响,并将测试结果与电解液阴极放电-原子发射光谱(ELCAD-AES)的分析结果进行比较。结果表明,当放电电压从600V升至720 V时,电子温度从2 000 K升至3 300 K,电子密度从2.47×10~(16)cm~(-3)降至1.77×10~(16)cm~(-3),Cd的发射光谱强度增强,灵敏度升高,检出限为1.22~2.95 mg/L。LGD-AES技术检测水中金属离子具有放电设备小型、能量消耗低、放电稳定性高、背景光谱干扰小和灵敏度高等优点。     

《原子发射光谱分析技术及应用》

该书以实际中广泛应用的发射光谱现代分析仪器为对象,介绍了原子发射光谱分析技术的原理和必要的基础知识,主要发射光谱仪器的分析技术及其实际应用。着重介绍火花源原子发射光谱、电感耦合等离子体发射光谱和辉光放电     

《原子发射光谱分析技术及应用》

该书以实际中广泛应用的发射光谱现代分析仪器为对象,介绍了原子发射光谱分析技术的原理和必要的基础知识,主要发射光谱仪器的分析技术及其实际应用。着重介绍火花源原子发射光谱、电感耦合等离子体发射光谱和辉光放电     

《原子发射光谱分析技术及应用》

该书以实际中广泛应用的发射光谱现代分析仪器为对象,介绍了原子发射光谱分析技术的原理和必要的基础知识,主要发射光谱仪器的分析技术及其实际应用。着重介绍火花源原子发射光谱、电感耦合等离子体发射光谱和辉光放电     

内嵌式液体阴极辉光放电光谱仪快速测定锂辉石中的锂

针对实验室现有的便携式液体阴极辉光放电光谱仪,重新设计了一种内嵌式液体阴极,其制作简单,采用蠕动泵直接进样,简化了便携式液体阴极辉光放电光谱仪的进样系统;刚玉阴极外管具有润湿作用,使得蠕动泵进样时阴极管口液面的起伏非常小,不会形成液滴,保证了放电的稳定、连续;可分析含低浓度HF的样品溶液,为简化锂辉石样品的前处理过程奠定理论基础,非常适用于野外现场分析锂辉石样品。选择Li的分析谱线波长为670.78 nm,利用新设计的内嵌式液体阴极,以3个锂矿石标样和11个锂辉石样品为研究对象,建立了锂辉石样品中Li的快速分析方法。在最佳工作条件下测得Li的检出限为4.6 ng/m L,方法的精密度(RSD)3%。研究表明,采用标准加入法获得的锂矿石标样和锂辉石样品的分析结果与ICP-M S的测量值基本吻合,相对误差均小于10%,满足野外现场快速分析锂辉石样品中Li含量的需要。     

千瓦级微波等离子炬-原子发射光谱(MPT-AES)在油液分析中的应用

采用千瓦级微波等离子炬-原子发射光谱(MPT-AES)装置对油液样品直接雾化进样分析,对直接稀释后的润滑油中8种金属元素进行了检测,并记录了进样时等离子体形貌的变化.结果表明,所有元素的校正曲线线性回归方程的R~2值均优于0. 995,精密度高,检出限接近传统的ICP-AES方法检出结果,为MPT-AES在油液视情维修中的分析监测及在线快速监测奠定了基础.同时还设计了一种油液在线混合进样装置,操作方便、进样量准确,适用于微量样品的采集和直接稀释及进样.     

辉光放电质谱法测定纯锡中24种杂质元素和锡记忆效应的消除

采用辉光放电质谱法(GDMS)测定了纯锡中24种杂质元素,分析方法为无标定量分析。分析前纯锡样品须依次用乙醇、水及乙醇冲洗以除去表面的灰尘颗粒,凉干后用于分析。本工作对辉光放电过程中的三项关键因素,即辉光放电电压、放电电流及放电气流三者在辉光放电溅射/电离时的相互关系及其对总离子流强度的影响进行了试验和讨论,并确定了仪器在最佳状态时辉光放电的优化条件为:放电电压590V,放电电流30mA,放电气流450mL·min~(-1)。为排除各元素测定中质谱(MS)干扰的影响,选择了在不同的分辨模式(中/高)下用相对丰度较高、干扰较少的质量数进行分析。所测定元素测定结果的相对标准偏差(n=5)均小于15%。各元素的检出限(3s)为0.003～0.174μg·g~(-1)之间。本方法所得测定结果与电感耦合等离子体原子发射光谱法(ICP-AES)或电感耦合等离子体质谱法(ICP-MS)的测定结果基本一致。经试验,通过更换GDMS的阳极帽、导流管、采样锥和透镜等4种耗材,可完全消除锡的记忆效应。     

电感耦合等离子体原子发射光谱法中悬浮液直接进样技术的研究与应用的进展

对电感耦合等离子体原子发射光谱法(ICP-AES)中的悬浮液直接进样技术的研究及应用的进展作了评述。文中引用文献涉及年份为1988~2005年。主要的评述内容包括试样制备方法、仪器装置、校准方法、影响悬浮液进样中的传输效率和雾化效率及分析结果可靠性的因素,以及此技术的分析应用(引用文献47篇)。     

液体阴极辉光放电原子发射光谱法测定盐矿中的K、Ca、Na、Mg

以铂针尖为阳极,毛细管顶端溢出的液体为阴极,建立了一种新型的液体阴极辉光放电原子发射光谱(LCGD-AES)分析检测系统。利用该系统同时测定了格尔木化肥厂盐矿中K、Ca、Na和Mg的含量。研究了放电电压、溶液流速、电解质种类、溶液pH值、干扰物对发射强度的影响,同时与离子色谱(IC)的测量结果进行比较。结果表明,在放电电压650 V、溶液流速3 m L·min~(-1)、pH 1. 0的HNO3作为电解液时,K、Ca、Na和Mg的检出限(LOD)分别为0. 100 0、0. 048 0、0. 002 4和0. 003 9 mg·L~(-1),相对标准偏差(RSD)分别为0. 57%、1. 8%、0. 94%和1. 8%。LCGD-AES对盐矿中K、Ca、Na、Mg的测试结果与IC的测定结果基本一致,样品回收率为95. 4%～108%。     

Slurry sampling fluorination assisted electrothermal vaporization-inductively coupled plasma-atomic emission spectrometry for the direct determination of metal impurities in aluminium oxide ceramic powders

A new analytical procedure for the direct determination of metal impurities (Cr, Cu, Fe and V) in aluminium oxide ceramic powders by slurry sampling fluorination assisted electrothermal vaporization-inductively coupled plasma-atomic emission spectrometry (ETV-ICP-AES) is reported. A polytetrafluoroethylene (PTFE) emulsion was used as a fluorinating reagent to promote the vaporization of impurity elements in aluminium oxide ceramic powders from the graphite tube. A vaporization stage with a long ramp time and a short hold time provided the possibility of temporal analyte-matrix separation. The experimental results indicated that a 10 microL 1% m/v slurry of aluminium oxide could be destroyed and vaporized completely with 600 micrograms PTFE under the selected conditions. Two aluminium oxide ceramic powder samples were used without any additional pretreatment. Analytical results obtained by using standard addition method with aqueous standard solution were checked by comparison of the results with pneumatic nebulization (PN)-ICP-AES based on the wet-chemical decomposition and analyte-matrix separation. The limits of detection (LODs) between 0.30 microgram g-1 (Fe) and 0.08 microgram g-1 (Cu) were achieved, and, the repeatability of measurements was mainly better than 10%.     

A comparison of slurry sampling electrothermal vaporization and slurry nebulization inductively coupled plasma mass spectrometry for the direct determination of trace impurities in titanium dioxide powder

A comparison of slurry sampling (SS)-ETV-ICP-MS and slurry nebulization (SN)-ICP-MS for direct determination of trace impurities in titanium dioxide powder is made. The particle size effect, matrix effect and analytical characteristics of SSETV-ICP-MS and SN-ICP-MS are compared. The results have shown that SSETV-ICP-MS has a lower particle size effect and matrix effect compared to SN-ICP-MS. The analytical performance of the two methods reveals that SSETV-ICP-MS and SN-ICP-MS have similar relative detection limits (in the nanogram per liter level); however, the former has a lower absolute detection limit than the latter. Although the precision for SSETV-ICP-MS is a little worse than that for SN-ICP-MS, it is still acceptable for real sample analysis. The two methods were successfully applied for the determination of trace impurities in titanium dioxide powder samples with particle sizes of less than 50 nm, but only SSETV-ICP-MS could be applied for the determination of trace impurities in titanium dioxide powder samples with a particle size of 1 microm.     

Direct inductively coupled plasma-atomic emission spectrometry analysis of trace elements in muscle tissues of hairtail using electrothermal vaporization with slurry sampling

A procedure for direct determination of trace elements in muscle tissue of hairtail was developed using inductively coupled plasma-atomic emission spectrometry and electrothermal vaporization with slurry sampling. Due to use of polytetrafluoroethylene as the chemical modifier, the vaporization behaviors of analytes from the slurry and the aqueous standard solutions were very similar. In this case, the aqueous standards could be used for the calibration of slurry samples. The main factors influencing this method were studied systematically. The detection limits for Cr, Ni, Zn, Cd, and Pb were 3.1, 10.5, 176, 6.9, and 83 ng/mL, respectively, and the relative standard deviations were less than 10%. The proposed method was applied to the determination of trace Cr, Ni, Zn, Cd, and Pb in hairtail samples with satisfactory accuracy and precision. A certified reference material of mussel (GBW 08571) was analyzed, and good agreement was obtained between the results from the proposed method and certificate values.     

Radiochemical neutron activation analysis of ultra-pure molybdenum-based microelectronic materials for detrimental impurities

A radiochemical neutron activation analysis method, based on the separation of the radionuclides by anion-exchange from a 20 mol/l HF/3% H₂O₂ medium, was applied to the analysis of ultra-high purity molybdenum oxide and molybdenum metal and high-purity molybdenum silicide for 29 elements including the detrimental impurities Co, Cr, Fe, K, Na, Ni, Th, U and Zn. The achievable limits of detection for these elements are between 0.02 ng/g (for Co) and 50 ng/g (for K). The results were compared with those obtained by glow discharge mass spectrometry, inductively coupled plasma atomic emission and mass spectrometry, isotope dilution mass spectrometry and slurry sampling and direct solid sampling ETAAS. On the basis of the comparison of the results, the feasibility of the methods for analysis of these ultrapure materials is discussed.Dedicated to Professor Dr. Dieter Klockow on the occasion of his 60th birthday     

Slurry sampling fluorination assisted electrothermal vaporization-inductively coupled plasma-atomic emission spectrometry for the direct determination of metal impurities in aluminium oxide ceramic powders

A new analytical procedure for the direct determination of metal impurities (Cr, Cu, Fe and V) in aluminium oxide ceramic powders by slurry sampling fluorination assisted electrothermal vaporization-inductively coupled plasma-atomic emission spectrometry (ETV-ICP-AES) is reported. A polytetrafluoroethylene (PTFE) emulsion was used as a fluorinating reagent to promote the vaporization of impurity elements in aluminium oxide ceramic powders from the graphite tube. A vaporization stage with a long ramp time and a short hold time provided the possibility of temporal analyte-matrix separation. The experimental results indicated that a 10 μL 1% m/v slurry of aluminium oxide could be destroyed and vaporized completely with 600 μg PTFE under the selected conditions. Two aluminium oxide ceramic powder samples were used without any additional pretreatment. Analytical results obtained by using standard addition method with aqueous standard solution were checked by comparison of the results with pneumatic nebulization (PN)-ICP-AES based on the wet-chemical decomposition and analyte-matrix separation. The limits of detection (LODs) between 0.30 μg g^–1 (Fe ) and 0.08 μg g^–1 (Cu) were achieved, and, the repeatability of measurements was mainly better than 10%. Received: 28 August 2000 / Revised: 1 November 2000 / Accepted: 12 November 2000     

Direct introduction of slurry samples in multi-syringe flow injection analysis: determination of potassium in plant samples.

The present work explores the slurry sampling approach for automatic, flow-based plant analysis. For this purpose, pinch valves were introduced into a multi-syringe flow injection analysis manifold to provide the repeatable aspiration of a few microliters of plant suspension before the material was further processed through the flow system. For validation of the proposed approach, the determination of potassium by flame emission spectrometry was implemented. Several parameters were studied: the concentration of plant particles in the sample suspension and the utilization of matrix modifiers. Microwave digestion was also implemented; no significant difference was found when certified reference material was analyzed with or without the in-line digestion step. The system was successfully applied to 13 samples within a concentration range of 2.5 to 100 mg g(-1). A determination frequency of 28 h(-1) was achieved and the precision was better than 4.0% (n = 12).     

Determination of impurities in titanium nitride by slurry introduction axial viewed inductively coupled plasma optical emission spectrometry

A method of slurry nebulization for inductively coupled plasma optical emission spectrometry (ICP-OES) applied to the analysis of titanium niride(TiN) was reported. The TiN slurry sample was prepared with adding dispersant polyacrylate amine or polyethylene imine for the stabilization and homogenization of suspension, and the amount of additives was optimized. A Babington type cross-flow nebulizer with V-groove was used for nebulization of the slurry for avoidance of blockage from the particles. The stability of slurry was characterized via zeta potential measurement, scanning electron microscope observation, particle size distrbution measurement and signal stability testing. For nm size TiN, calibration curves could be established by aqueous standards and the analytical results were in good accordance with the alkaline fusion method. For μm size TiN, a negative deviation was observed for most of elements and this deviation can be corrected by using Ti intrinsic internal standard method.     

Comparative determination of Ba, Cu, Fe, Pb and Zn in tea leaves by slurry sampling electrothermal atomic absorption and liquid sampling inductively coupled plasma atomic emission spectrometry

The comparative determination of barium, copper, iron, lead and zinc in tea leaf samples by two atomic spectrometric techniques is reported. At first, slurry sampling electrothermal atomization atomic absorption spectrometry (ETAAS) was applied. The results of Ba and Pb determination were calculated using the method of standard additions, and results of Cu, Fe and Zn from the calibration graphs based on aqueous standards. These results were compared with the results obtained after microwave-assisted wet (nitric+hydrochloric+hydrofluoric acids) digestion in closed vessels followed by inductively coupled plasma-atomic emission spectrometric (ICP-AES) determination with the calibration by means of aqueous standards. The exception was lead determined after a wet digestion procedure by ETAAS. The accuracy of the studied methods was checked by the use of the certified reference material Tea GBW-07605. The recoveries of the analytes varied in the range from 91 to 99% for slurry sampling ETAAS, and from 92.5 to 102% for liquid sampling ICP-AES. The advantages of slurry sampling ETAAS method are simplicity of sample preparation and very good sensitivity. Slurry sampling ETAAS method is relatively fast but if several elements must be determined in one sample, the time of the whole microwave-assisted digestion procedure and ICP-AES determination will be shorter. However, worse detection limits of ICP-AES must also be taken into the consideration in a case of some analytes.     

Direct solid sampling electrothermal vaporization of alumina for analysis by inductively coupled plasma optical emission spectrometry

A procedure based on electrothermal evaporation (ETV) and inductively coupled plasma atomic emission spectrometry (ICP-OES) for the determination of trace impurities in Al₂O₃ powders without any sample pretreatment is presented. With the aid of matrix modifier the transport and the evaporation efficiency for refractory compounds could be increased by forming halides with a lower boiling point. As calibration is still a problem in direct solid sample analysis, different calibration approaches including the use of certified reference materials from NIST and standard addition of aqueous solutions of analytes were discussed. The accuracy obtained with calibration and with the standard addition method was shown up for the elements Ca, Fe, Ga, Mg, Mn, Na, Ni and V for the case of Al₂O₃ NIST standard reference material (SRM 699). The ETV–ICP-OES method was used for the analysis of Al₂O₃ powders with impurities in the low μg/g range and the results for the elements Ca, Fe, Ga, Mg, Mn, Na, Ni and V obtained with evaporation of discrete powder amounts with ETV–ICP-OES and slurry evaporation under the use of ultrasonic homogenization during the sampling and ETV–ICP-MS were shown to be in a good agreement.     

Slurry sampling electrothermal atomic absorption spectrometry for trace element analysis of high-purity tungsten trioxide

A slurry sampling ETAAS method for the determination of trace concentrations of Ca, Co, Cr, Cu, Fe, K, Mg, Na and Ni in tungsten trioxide is presented. A high background absorption appearing with large sample amounts during atomization at high temperatures was the only matrix interference observed. It could be significantly reduced by volatilization of the matrix in the pyrolysis step. Calibration curves recorded with aqueous standards could be used for calibration in all cases excluding the determination of very low analyte concentrations of Co and Fe which required the use of the standard additions method. The results obtained by this method showed an excellent agreement with those determined in digests by ETAAS. The detection limits achievable by the slurry technique were between 1 (Ca, K, Mg, Na) and 210 (Cu) ng/g. They were mostly by more than one order of magnitude better than those of the solution techniques. Received: 9 July 1997 / Revised: 6 October 1997 / Accepted: 10 October 1997