加速溶剂萃取―气相色谱―质谱法测定土壤中酞酸酯类有机物

建立了土壤中酞酸酯类的加速溶剂萃取（ASE）―气相色谱―质谱（GC-MS）测定方法。通过对萃取溶剂和层析柱的优化选择,得出优化萃取条件。同时,实验过程中采用铬酸洗液对实验器皿进行清洗,有效控制了环境中酞酸酯对样品的污染。该优化方法结果显示：平均加标回收率为89.5%～106.0%,相对标准偏差为1.5%～5.8%,检出...     

提高现有痕量分析水平的探讨

本文讨论了空白值对痕量分析精密度的影响,通过实例对所导出的公式加以验证,认为最好把空白值降至测定含量的1/10。阐述了来自试剂、器皿、环境及其操作的污染,并探讨了改善及提高现有方法的途径。     

石墨炉原子吸收光谱法测定保健品松花粉中痕量铅

实验通过采用优级纯以上试剂降低本底,多道程序清洗器皿控制污染,通过控制酸量改善测定铅的信噪比,降低检出限,引入基体改进剂磷酸二氢铵消除基体干扰.优化石墨炉检测条件下,松花粉样品中铅的加入平均回收率达到90％以上.使用标准物质(茶叶GBW10016)对该方法进行了验证,结果表明铅的测定值在标准物质的保证值范围内.该方法能...     

浊点萃取-分光光度法测定自来水及酒类样品中的痕量铁

利用非离子表面活性剂TritonX-100在温度高于其浊点时形成相分离行为,建立了浊点萃取-分光光度法测定痕量铁的新方法,探讨优化了以KSCN为显色剂,TritonX-100浊点萃取富集痕量铁的实验条件.研究发现:加入正辛醇可使TritonX-100的浊点降低约30℃,有利于萃取实验的进行;同时,加入的正辛醇与TritonX-100对痕量铁起到了协同萃取作用.在优化了的实验条件下,进行了痕量铁的分析,检出限为0.02mg·L-1,加标回收率为97.4%～101.6%,应用于自来水及酒类样品中痕量铁的测定,结果满意.     

共价氢化物与汞离子反应的研究：痕量锗高灵敏度分析方法

报道了一种氢化物发生－冷原子荧光法间接测定痕量锗的新方法。找出最佳实验条件并将此法用于植物及水样中痕量锗测定，结果令人满意。方法简便、快速、灵敏。对水中痕量锗检出限０．１μＬｇ／Ｌ，回收率９２％以上。     

茜素红-H2O2-溴代十六烷基吡啶-丙氨酸体系催化光度法测定痕量锰

研究了在溴代十六烷基吡啶(CPB)增敏剂和丙氨酸活化剂存在下,锰(Ⅱ)对过氧化氢氧化茜素红的褪色反应及其动力学条件,建立了测定痕量锰(Ⅱ)的新方法。讨论了pH值和共存离子对痕量锰(Ⅱ)测定的影响。在最佳实验条件下,本法测定痕量锰(Ⅱ)的线性范围为10~360μg/L,检出限为2.01×10-8g/L。方法用于水样中痕量锰(Ⅱ)的测定,结果满意。     

固相微萃取膜器富集痕量氧气的研究

介绍了一种固相微萃取膜器对高纯气体中痕量氧气的富集预浓缩方法,分析了气体膜分离的影响因素,实验结果表明,在操作压力为0.4 MPa,温度为40℃的条件下,该膜器对高纯气体中痕量氧气有较强富集效果,浓缩倍数介于3.69~6.3之间。     

催化动力学光度法测定水中痕量钒

基于在H3PO4介质中, 抗坏血酸作活化剂, 100 ℃沸水浴加热的条件下, 痕量钒V(Ⅴ)催化溴酸钾氧化三溴偶氮氯膦(TB-chorophosphonazo)的褪色反应, 建立了新的测定超痕量钒的催化光度法. 该方法对钒测定范围是0～1.0 ng/mL, 检出限为0.133 ng/mL. 实验考察了影响催化反应速率的各种因素, 确定了最佳的实验条件. 实验测定了反应的动力学参数: 表观活化能Ea'=93.80 kJ/mol, 表观速率常数为k'=1.307×10-3 s-1, 建立了催化反应动力学方程. 方法灵敏度高, 选择性好, 直接用于环境水体中痕量钒的测定.     

环境样品中痕量甲醛的催化荧光动力学分析

基于在硫酸介质中, 痕量甲醛能促进溴酸钾氧化吡咯红并使其荧光强度减弱的反应, 建立了动力学荧光法分析测定痕量甲醛的新方法. 研究了温度、时间, 各种试剂浓度等条件对测定的影响. 在最佳实验条件下, 方法的线性范围是8～200 ng/mL, 检出限为6.1 ng/mL. 该方法用于环境水样、室内空气、食品中痕量甲醛的测定, 并与乙酰丙酮分光光度法进行了对照, 结果无显著性差异.     

爆炸残留物的毛细管电泳检测

1引言爆炸是恐怖袭击的常用手段。对痕量爆炸残留物进行高效检测,从而准确判断炸药的成分和种类,能够为侦破案件提供重要的线索和证据[1,2]。近年来,毛细管电泳技术初步显示了其在爆炸物检验方面的巨大潜力[3～6]。本实验基于毛细管电泳间接紫外吸收检测[7,8]和胶束电动色谱[9],建立了痕量爆炸残余物的系统分析检验方法,通过对爆炸瞬间产生的痕量     

Depth profiling of ultra trace metal impurities in polytetrafluoroethylene wares by surface scraping and acid-vapor extraction followed by ICP-MS analysis.

This paper describes the development of the depth profiling method of ultra trace metal impurities in polytetrafluoroethylene (PTFE) wares based on contamination-free sampling followed by acid-vapor extraction and its application to evaluate the washing method for PTFE wares. A contamination-free sampling process was achieved by scraping the surface of PTFE wares with the cleft face of a silicon wafer followed by exposing the PTFE scraped to highly pure acid-vapor. The concentration of metal impurities in extractants was determined by ICP-MS equipped with an electrothermal vaporizer (ETV-ICP-MS). The blank values of Al, Cr, Fe, Ni and Cu by the depth profiling method were 0.006, 0.004, 0.005, 0.002 and 0.003 ng, respectively. By analyzing the depth profile of beakers, the distributions of ultra trace (ng g(-1) level) metal impurities were clarified. An examination of the washing methods by the depth profiling method also clarified that exposing to acid-vapor was more effective than the acid-dipping method for the elimination of metal impurities.     

Trace metal impurities in silica as a cause of strongly interacting silanols

Summary The paper describes nuclear activation analysis of several chromatographic grade silicas for the determination of trace metals. The effect of acid washing is described and the effect of trace metals on the acidity of surface silanols is discussed. A correlation has been found between the concentration of metal traces in the layer of silica adjacent to the surface and the concentration of strongly interacting sites.     

Total digestion of silicate containing matrices (plants,soil, sludges) using a pressure ashing device with PFA-vessels

A digestion procedure for silicate containing matrices like soil, sludge, etc. by using a commercially available pressure ashing device (Seif-Aufschlutechnik, Germany) with PFA (perfluoroalkoxy) sample vessels is described at the results for different matrix- and trace elements in different suitable certified standard reference materials. The advantages of this technique compared with the use of Teflon®-(PTFE, polytetrafluoroethylene) vessels and the open treatment in Pt-crucibles will be discussed.     

Preparation of Hair and Nail Samples for Trace Element Analysis

Abstract

The method of washing of human hair and nail samples is examined by neutron activation and γ-ray analysis. The amounts of Na, K, Br, Au, Zn and La that are removed by successive washings determine the optimum number of washing for removing these trace elements as surface contaminants. A total solution contact time with the nails is 5 minutes, and leaching effects are observed after 6 washings.     

Surface Corrosion Studies on High-Purity Quartz Vessels for Digestive Sample Preparation

 High purity quartz is the most common material for pressure vessels of high pressure digestion systems. Such systems are in worldwide use especially for matrix decomposition and mineralization procedures with either conventional heating or heating in a microwave field. Usually, the quartz vessels are used for hundreds of decompositions and corrosive attack is often already visible with the bare eye. On the other hand it is well known that adsorption as well as leaching phenomena increase with rising surface roughness of a material. This is especially critical in trace and ultratrace work. For the latter such interactions with the vessel wall might even become the limiting factor in ultratrace determinations at the ng/g-level and below. Therefore, systematic morphological and compositional investigations by high resolution scanning electron microscopy were performed on the inner surfaces of decomposition vessels which were subjected to a rising number of digestions under pressure in a Multiwave digestion apparatus. Milk powder was digested with nitric acid for these investigations. Rising corrosive attack was observable but did not lead to severely damaged surfaces. The latter were found on a quartz pressure vessel for an HPA-digestion apparatus which was in intensive use over a long time. Recrystallization was also observable in this case. In addition to investigations by scanning electron microscopy, FT-NIR-Raman spectroscopy was also applied for the surface characterization of the various quartz vessels. The onset of recrystallization is detected much earlier with this method than by morphological changes in the scanning electron microscope (SEM). It appears that the combination of surface morphological and topochemical investigations in the SEM with vibrational spectroscopy is ideal for an optimal characterization of corroded quartz surfaces. Received January 15, 2001. Revision April 14, 2001.     

Preparation and characterization of an immunoaffinity chromatography column for the selective extraction of trace contraceptive drug levonorgestrel from water samples

The preparation and characterization of an immunoaffinity chromatography (IAC) column for the specific extraction and enrichment of trace contraceptive drug levonorgestrel (LNG) from water samples were described. The IAC column was constructed by covalently coupling specific polyclonal antibody against LNG to CNBr-activated Sepharose 4B and packed into a common solid phase extraction (SPE) cartridge. The extraction conditions including loading, washing and eluting solutions, as well as the effect of flow rate on the extraction were carefully optimized. Pure water, 5% of methanol and 50% of methanol were respectively selected as loading, washing and eluting solutions, while the flow rates in the loading, washing and eluting steps were selected to be 1.0, 2.0 and 0.5 mL min⁻¹, respectively. Under optimal conditions, the IAC column was characterized in terms of maximum capacity, extraction recovery and stability. It was found that, for IAC column packed with 0.2 g of solid support immobilized with antibody, the maximum capacity for LNG was about 260 ng. The extraction recoveries of the column for LNG at three different spiked concentrations were within 95.3-106.9%. After more than 35 times repeated usage, there was not significant loss of specific recognition. Using high performance liquid chromatography (HPLC) as an analytical tool, trace amount of LNG in the range of ng L⁻¹ was found in river water and wastewater samples after 600-fold enrichment, demonstrated the feasibility of the prepared IAC column for LNG extraction.     

Contamination with cadmium from micropipette tips

Contamination by cadmium from micropipette tips from two different manufacturers was tested. Tips were washed with two different acids and the washing solutions were analysed by atomic absorption (graphite furnace). The washed tips were controlled by analysing pure acids and were found decontaminated. Clear contamination was found in yellow Eppendorf pipettes, which varied according to the consignment. The decontamination of disposable micropipette tips is emphasized when trace metal contamination should be avoided.     

Determination of minor elements in soil profiles by neutron activation analysis

Soil samples are often used in an effort to place a suspect at a particular location, i. e., material from the suspect's shoes, clothes, car, etc. is compared with soil from the crime area. The trace element concentration in both samples has been used to establish identity; this has been obtained usually by use of neutron activation analysis. In rural areas and farms more than half a dozen different kinds of soil may be present, and each soil may consist of several horizons. Horizons in turn may be broken down into sub-horizons or transitional layers, depending upon the humus present and the amount of weathering. Thus it would appear that comparison of soil samples would require rather exhaustive knowledge of the terrain, depth, and history of the samples area since variations of the elements in the soil are affected by eluviation (washing out) or illuviation (washing in). Such variations are illustrated by showing the change of concentration of elements with soil depth. Even though most forensic applications require comparisons of only the top inch or two of soil, the samples must be classified as to depth and type of soil since man often change the soil profile (ploughing, construction, etc.), or nature does (rain, decay, etc.). We have collected a number of soil samples from a several square mile area in both the horizontal and vertical profile. These soils were dried, thoroughly mixed, and portions, irradiated for one minute (for short half-life induced activities), and one week (for long half-life activities) at a flux of ∼10 n·cm⁻²·sec⁻¹. Standards were irradiated in the same manner as samples. A number of elements were determined non-destructively; chemical separation was performed to determine others. Our results indicate great variation (factors of two or more occur in the concentration of many trace elements in going from the surface to several inches below. Similar variations occur in the horizontal plane. These data ind ate that comparison of soil samples by use of trace element concentrations is subject to considerable uncertainty. If large variations can be found within a small sampling area, the statistical significance of apparent agreement between two samples appears highly questionable. Research sponsored by the U. S. Atomic Energy Commission under contract with the Union Carbide Corporation.     

The cluster analysis technique of pattern recognition: application to the trace metal composition of cardiovascular tissues.

Application of the statistical method of cluster analysis as a pattern recognition technique was investigated by classification of cardiovascular tissues on the basis of their trace metal composition. The distribution patterns of 13 trace metals among 17 tissues of the heart and its appended blood vessels were determined. Cluster analysis of the data resulted in ready differentiation of tissues derived from ordinary and specialized myocardium from those of blood vessels and heart valves. Further similarities and differences among the 17 tissues were identified by comparing the patterns generated when different numbers of groups (i.e., 3, 4, 5, 6, and 7 groups) were designated. It is suggested that cluster analysis may provide a generally useful tool in the interpretation of data from multi-phasic laboratory testing procedures.