流动注射氢化物石墨炉原子吸收法的应用研究 Ⅰ.——实验装置与分析性能

氢化物石墨炉联用技术的原理是先在较低温度下将氢化物蒸气通入石墨炉并分解沉积于石墨管的内表面,然后再在高温下原子化。该法能明显提高灵敏度,消除液相和气相干扰。本文采用自制的半自动氢化物石墨炉进样系统及流动注射氢化物发生器,直接在普通石墨炉上进行氢化物石墨炉分析,研究了部分元素的测定条件,建立的方法操作方便,灵敏度高,耗样少,线性范围宽,是一种值得推广的新方法。     

Atomic absorption spectrometric determination of manganese, silver and zinc in dental material by atomization directly from the solid state

The direct-atomization. technique of atomic absorption spectrometry was applied to the determination of manganese, silver and zinc in 14 whole erupted or unerupted human teeth. Pulverized sample-graphite mixtures of 5–10 mg, to which known volumes of metal standard solution had been added, were dried, ashed and atomized in a graphite furnace, as in the standard addition technique. The technique was also used for determining silver and zinc in an international reference sample of calcined animal bone.     

Status and future prospects for use of the graphite furnace for elemental trace analysis of liquids and solids

Summary An overview of the versatility and use of the graphite furnace for elemental trace analysis of liquids and solids using spectrochemical detection is presented. The analytical performance of conventional graphite furnace atomic absorption spectrometry is compared to other popular state of the art spectrochemical techniques with respect to detection power, precision, sample compatibility and throughput. Some applications of the graphite furnace to practical problem solving in trace analysis are highlighted, including its use with atomic absorption, coherent forward scattering, laser excited atomic fluorescence, laser enhanced ionization and coupled methodologies. Prospects for future use and evaluation are given.     

Quantitative element analysis by isotope dilution in diode laser graphite furnace atomic absorption spectrometry

The paper reviews the application of the isotope dilution technique in optical atomic absorption spectrometry by use of a low-pressure graphite tube furnace as atomizer and diode lasers as radiation sources. The principles and the methodology to obtain accurate quantitative results despite of the occurrence of interferences are presented. The successful application of different Doppler-limited and Doppler-free spectrometric techniques is also presented. The perspectives but also the limitations of this new method are discussed.     

Direct determination of traces of copper,zinc, lead,cobalt, iron and cadmium in bovine liver by graphite furnace atomic absorption spectrometry using the solid sampling and the platform techniques

A simple and rapid method is described for direct determination of traces of Cu, Zn, Pb, Co, Fe and Cd in NBS bovine liver, SRM 1577, by graphite furnace atomic absorption spectrometry. The solid sampling technique was used, thereby avoiding the dilution factor involved in the solution technique, and also the risk of contamination from the environment in sample handling and from reagents, solvents and vessels. The organic matrix was burnt off and removed by using a well-defined selective volatilization technique combined with the analyte modification technique. Also, the effect of the platform technique in removing matrix interferences was studied using an anisotropic pyrolytic graphite platform inside the commercial graphite tube. The results of the “with platform” and the “without platform” techniques were equally accurate, but the “with platform” technique gave better precision.     

Direct determination of lead in bovine liver by solid sampling with graphite furnace atomic absorption spectrometry—a comparison of tube wall atomization, platform atomization and probe atomization

A comparative study of three atomization techniques is presented: tube wall atomization, platform atomization and probe atomization, in graphite furnace atomic absorption spectrometry for direct determination of lead in bovine liver. Also presented is the effect of oxygen ashing on the lead atomic absorption signal and on the background absorption due to the organic matrix of bovine liver. Study of the lead atomic absorption pulses given by the three atomization techniques using a detection system having a short time constant relative to the atomization and the residence time of lead from Bovine Liver, SRM No. 1577, has provided a new insight into the atomization processes involved in the techniques. The importance of isothermal atomization in reducing or eliminating matrix interferences and the role of oxygen gas in the ashing cycle are presented and discussed.     

Microdetermination of silicon in blood, serum, urine, and milk using furnace atomic absorption spectrometry

A simple, direct microanalytical method for quantitative determination of silicon in human whole blood, serum, urine, and milk by furnace atomic absorption technique has been developed. The method employs standard additions and combines the inherent specificity and simplicity of atomic absorption analysis with the greatly increased sensitivity possible with a heated graphite tube atomizer for the determination of silicon in microliter samples. The sensitivity of the method is 1.3 ng. The method is suitable for the direct analysis of silicon with no sample preparation other than dilution with deionized water, thereby minimizing contamination due to sample preparation. The relative standard deviation for 10 μl of blood (1:1), serum (1:1), urine (1:7), and milk (1:1) was 3.45% or less.     

Some observations on electrothermal vaporisation for sample introduction into the inductively coupled plasma

The development and analytical utility of electrothermal vaporisation techniques employing a graphite rod for sample introduction into the inductively coupled plasma (ICP) are assessed. In most instances detection limits are superior to those obtained with nebulisation based systems, and are comparable to those obtained with graphite furnace atomic absorption spectrometry. A model is derived for the sample injection process. Additionally the major interference and alteration of the plasma excitation phenomena ensuing from the sample introduction of a solvent free aerosol are discussed in order to assess the analytical potential of the technique for routine μl volume sample introduction in ICP spectrometry. The capability for simultaneous multi-element analyses is maintained with the electrothermal vaporisation technique.     

Analysis of lead and tin in strong brine and high iron systems using the microsampling technique

The development of hydrometallurgical techniques such as the iron(III) chloride-sodium chloride system for the recovery of metals from scrap materials necessitates the analyses of these metals in a high salt medium during the recovery studies. An alternative method for the analysis of lead and tin in strong brine and high iron systems by flame atomic absorption spectrometry is a microsampling technique in combination with in situ standard addition. Relative standard deviations of 1.2% and 2.2% were obtained for the analysis of lead and tin respectively. The accuracy for the method is also satisfactory with recoveries ranging from 90% to 102%. The microsampling technique is rapid and simple, requires small volumes of sample and offers no clogging problems during the atomic absorption analyses.     

Optimization of the determination of selenium in marine samples by atomic absorption spectrometry: Comparison of a flameless graphite furnace atomic absorption system with a hydride generation atomic absorption system

A comparison has been made between a graphite furnace system based on nickel as a matrix stabilizing metal and an automated hydride generation system with a heated quartz cell. The effect of nickel as a matrix modifier was studied in pure selenite solutions as well as in biological matrixes by different charring temperatures. The suppression effect of different acids on the response of the analyte is reported and discussed. The use of an electrically heated quartz tube as an alternative to the argon hydrogen flame method unproved the selenium determination by hydride generation atomic absorption. The effect of hydrochloric acid to secure quantitative formation of selenium (IV) and the interference of copper in the response measurements have been studied. Further a comparison has been made between three different digestion procedures when the hydride generation atomic absorption system was applied. The results of the graphite furnace atomic absorption and the hydride generation atomic absorption were found to be equally accurate, but the graphite furnace technique gave better reproducibility.     

A rapid and simple method for the determination of trace metals in hair samples by atomic absorption spectrometry

Acid digestion procedures are described for the dissolution of human head hair in routine determinations of cadmium, chromium, mercury, lead and zinc in the same sample solution by means of atomic absorption spectrometry. The techniques employed are atomization in a Massman graphite furnace or in an air—acetylene flame; the cold-vapor cell is used for mercury. The entire analytical procedure is tested with powdered homogenized head hair samples, previously analyzed by other analytical techniques. Comparison of the results demonstrates that the proposed technique is at least as precise and accurate as the other procedures used.     

Determination of cadmium in the livers and kidneys of puffins by carbon furnace atomic absorption spectrometry.

A carbon furnace atomic absorption procedure is described for the determination of cadmium in the livers and kidneys of puffins, fratercula arctica. Samples are dried and weighed and 2 to 100 mg are dissolved in sulphuric and nitric acids. These solutions are analysed directly in the carbon furnace against aqueous standards and provide accurate results in the range 0-1 to 100 micrograms/g dry weight. The method is simple and rapid and requires much less of the small total sample than would be required for flame atomic absorption.     

塞曼石墨炉原子吸收光谱法测定大鼠血,尿,肾,肝中的微量金

采用石英管加入少量硝酸高温消化的方法,用塞曼石墨炉原子分光光度计对服用含金救心丸的大鼠血,尿,肝,肾进行微量金的测定。测定方法简便快速,结果满意。     

Analysis of submicroliter samples using micro thermospray flame furnace atomic absorption spectrometry

A recently described thermospray flame furnace atomic absorption spectrometric (TS-FF-AAS) system has been modified in order to extend the applicability of the method for the determination of elemental traces in very small sample volumes (microliter or submicroliter). As an easily available, effective thermospray vaporizer, a fused silica capillary was used and the liquid sample was transported by 1 MPa (10 bar) gas pressure delivered by a standard gas cylinder. A 0.3 microL sample volume can be analyzed with a higher power of detection than using 3 orders of magnitude larger sample volumes with conventional flame atomic absorption spectrometry. The relative standard deviations (N=12) for 0.3 microL volumes and 5 microg/mL Pb samples amount to 3.1% and 3.8% in signal height and signal area, respectively. The detection limit was found to be 69 ng/mL. Initial experiments with other elements (Cd, Hg, Tl, Zn) led to similar results.     

The determination of platinum in biological materials by electrothermal atomic absorption spectroscopy

Methods for determination of platinum in body tissues and fluids by electrothermal atomic absorption spectroscopy are described. Serum and urine could be analyzed without pretreatment or dilution. Wet and dry ashing techniques for tissue digestion were compared. Dry ashing tissues in a furnace resulted in significant and unexplained losses of analyte, whereas there was complete recovery of platinum added to the tissues when the tissues were wet ashed. The wet ashing technique is fast and convenient and requires minimal sample treatment.     

固体直接进样石墨炉原子吸收法测定土壤中镉元素

固体直接进样是近年来石墨炉原子吸收分析领域发展较快的技术,它取代了繁冗的对固体样品的前处理,避免了样品的污染和损失,也保护了操作人员的身体健康。采用固体直接进样-石墨炉原子吸收光谱仪,结合使用持久化学改进剂对环境土壤样品中Cd元素进行测定,其结果表明,方法检出限为0.002 66ng,定量测定下限为0.008 87ng,相对标准偏差RSD≤10%,方法准确、可靠,均满足环境土壤测试方法的要求。     

Signal processing and detection limits for graphite furnace atomic absorption with Zeeman background correction

The signal handling requirements for graphite furnace atomic absorption are much more demanding than those for flame atomic absorption. Graphite furnace signals change rapidly, background levels are higher, and signal interpretation needs are more extensive.We have identified a number of signal generation and processing factors that are important for success in graphite furnace analyses. These include: use of the transverse, a.c. Zeeman technique with the magnet on the analyte for background correction; production of a series of signal integrals at line frequency to accurately represent the shape of the furnace peak; use of interpolation techniques to better correct for rapidly changing background levels; use of integrated peak absorbance (A.s) signals rather than peak height absorbance for quantitative measurements; use of baseline correction to improve the accuracy of integrated peak absorbance signals; and use of graphical techniques to facilitate data interpretation and methods development.Examples are presented that illustrate the contribution of these factors to precision and detection limit performance. It is possible to improve detection limits over those previously reported by choosing appropriate signal handling parameters.     

Analysis of Malodorous Sulfur Gases and Volatile Organometalloid Compounds in Landfill Gas Emissions Using Capillary Gas Chromatography with Programmed Temperature Vaporization Injection and Atomic Emission Detection

Volatile compounds containing Group V and Group VI elements in landfill gases are of concern as a source of toxic pollutants and unpleasant odors. Conventional analytical techniques for these compounds e.g. ICP-MS, ICP-AES are complicated, expensive and time consuming. The use of a simple programmed temperature vaporization injection (PTV) technique coupled to gas chromatography with atomic emission detection (GC-AED) has been successfully demonstrated to identify compounds containing arsenic, antimony, and sulfur in landfill gas. With an adapted PTV injection system (using a combination of a ten-port and a six-port Valco valves), problems associated with AED discharge tube damage due to high carrier gas flow rate during sample loading can be overcome. The gas samples generated from both a laboratory biowaste digester and a domestic landfill site were characterized using these techniques. Large sample gas volumes were adsorbed onto a cooled sorbent trap containing Porapak Q, followed by rapid liberation onto a porous layer open tubular column (PLOT) using programmed thermal desorption. Arsenic and antimony were also detected in the landfill leachate collected from the same landfill site using hydride generation-atomic absorption spectrometry (Hy-AAS). The efficiency of different traps has also been compared.     

Sensitive detection of ionic organolead compounds by coupling hydride generation (HG) with transversely heated graphite atomizer-atomic absorption spectrometry (THGA-AAS)

The detection of ionic alkyllead compounds using the coupling of flow injection analysis system-hydride generation (FIAS-HG) with transversely heated graphite atomizer atomic absorption spectrometry (THGA-AAS) has been worked out. Very low limits of detection can be achieved if the hydride products are enriched in the graphite furnace. Under optimised conditions (concentration of sodium borohydride, hydrogen peroxide and acidity as well as the furnace temperature) calibrations are carried out in the range of 0.1 to 5 μg/L. With a 1.5 mL sample loop, the limit of detection is calculated to be about 7 ng/L, but it can be lowered to below 1 ng/L if larger sample volumes are used for the enrichment.     

The determination of lead in blood by atomic absorption with the high-temperature graphite tube

The use of the high-temperature graphite tube with atomic absorption constitutes an exceptionally sensitive analytical method. Since only very small quantities of sample are needed, this method is highly suitable for the determination of lead in whole blood, especially when blood must be drawn from children. A technique which requires little preparation of the sample has been developed for such determinations. The graphite tube system developed can be used on any of a number of atomic absorption spectrophotometers and is better suited to routine analyses than the methods of L'vov and Massmann who pioneered the use of graphite tubes.