Atomic absorption spectrometry (AAS) – a versatile and selective detector for trace element speciation

AAS as a highly sensitive and specific single element technique is ideally suited as a detector for speciation analysis. The combinations of chromatographic separation with element specific detectors (flame AAS, electrothermal AAS (ETAAS), hydride generation AAS (HGAAS)) provide powerful approaches to the determination of all species. Sample stabilisation is the area that requires most attention as it still represents the main source of problems encountered in speciation work. The correct speciation depends on how the sample is handled prior to analysis. Unfortunately, no universal procedure has been found. Anything that changes redox conditions, pH or complexation equilibrium is clearly unacceptable.     

Improvements of Speciation Analyses in Environmental Matrices

The release of some organometallic compounds and other chemical forms of elements in the environment has led to great international concern because of their high toxicity. The validation of the analytical techniques became of paramount importance which led the Community Bureau of Reference (BCR) to decide on the organisation of a series of projects for the improvement of the quality of speciation analyses. In addition, it was found useful to discuss thoroughly the different sources of error likely occurring in speciation analyses and a workshop was organized for this purpose; the aim of this workshop was to discuss the state of the art of speciation determinations, to define use, applicability and necessity of determinations of element species, to investigate where limitations exist and discuss the work necessary to overcome these and to detect where techniques have sufficiently been developed to produce reliable and valuable results. This paper presents the organization of the workshop, its main issue and describe the state of the current BCR projects on speciation.Abbreviations AAS Atomic absorption spectrometry - CVAAS Cold vapour AAS - DPP Differential pulse polarography - ECD Electron capture detector - ETAAS Electrothermal AAS - FIA Flow injection analysis - FID Flame ionisation detector - FLUOR Spectrofluorimetry - FPD Flame photometric detector - GC Gas chromatography - HG Hydride generation - HPLC High performance liquid chromatography - HPLC-AES HPLC atomic emission spectrometry - INAA Instrumental neutron activation analysis - ICPAES Inductively coupled plasma AES - MS Mass spectrometry - QFAAS Quartz furnace AAS - RNAA Neutron activation analysis with radiochemical separation     

火焰原子吸收光谱法分析沉积物中重金属元素的形态

采用原子吸收光谱法研究了金沙江攀枝花段水系沉积物中重金属的形态及分布特征。研究发现,各重金属的形态以残渣态为主,离子交换态含量很少。同时说明原子吸收光谱法完全可以用来研究重金属形态特征,在环境研究中具有重要意义。     

Analytical methodologies for aluminium speciation in environmental and biological samples – a review

It is recognized that aluminium (Al) is a potential environmental hazard. Acidic deposition has been linked to increased Al concentrations in natural waters. Elevated levels of Al might have serious consequences for biological communities. Of particular interest is the speciation of Al in aquatic environments, because Al toxicity depends on its forms and concentrations. In this paper, advances in analytical methodologies for Al speciation in environmental and biological samples during the past five years are reviewed. Concerns about the specific problems of Al speciation and highlights of some important methods are elucidated in sections devoted to hybrid techniques (HPLC or FPLC coupled with ET–AAS, ICP– AES, or ICP–MS), flow-injection analysis (FIA), nuclear magnetic resonance (²⁷Al NMR), electrochemical analysis, and computer simulation. More than 130 references are cited.     

On-line hyphenation of capillary electrophoresis with flame-heated furnace atomic absorption spectrometry for trace mercury speciation

Capillary electrophoresis (CE) was directly interfaced to flame-heated furnace atomic absorption spectrometry (FHF-AAS) via a laboratory-made thermospray interface for nanoliter trace element speciation. The CE-FHF-AAS interface integrated the superiorities of stable CE separation, complete sample introduction, and continuous vaporization for AAS detection without the need of extra external heat sources and any post-column derivation steps. To demonstrate the usefulness of the developed hybrid technique for speciation analysis, three environmentally significant and toxic forms of methylmercury (MeHg), phenylmercury (PhHg), and inorganic mercury (Hg(II)) were taken as model analytes. Baseline separation of the three mercury species was achieved by CE in a 60 cm long x 75 microm inner diameter fused-silica capillary at 20 kV and using a mixture of 100 mM boric acid and 10% v/v methanol (pH 8.30) as running electrolyte. The precision (relative standard deviation, RSD, n = 7) of migration time, peak area and peak height for the mercury species at 500 microg x L(-1) (as Hg) level were in the range of 0.9-1.2%, 1.5-1.9%, and 1.4-2.0%, respectively. The detection limit (S/N = 3) of three mercury species was 3.0 +/- 0.15 pg (as Hg), corresponding to 50.8 +/- 2.4 microg x L(-1) (as Hg) for 60 nL sample injection, which was almost independent on specific mercury species. The developed hybrid technique was successfully applied to the speciation analysis of mercury in a certified reference material (DORM-2, dogfish muscle).     

Atomic absorption spectrometry — pregnant again after 45 years

Because atomic absorption spectrometry (AAS) seems to be so simple at first glance, its forthcoming end and replacement by more exciting techniques has been forecasted more than once over the past 45 years. However, AAS has received strong impetus again and again, e.g. by the introduction of the graphite furnace technique, and of flow injection, to mention but a few. Although more and more researchers, and even more instrument manufacturers are turning their back on AAS these days, this author believes that AAS is about to give birth to new offspring in the very near future. The most important ones are solid sampling and speciation analysis on the application side, a much deeper exploitation of the potential of flow injection analysis, the use of diode lasers as radiation sources, and the introduction of continuum-source AAS on the instrumental side. The latter could replace conventional line-source AAS in the foreseeable future because of its obvious advantages in essentially all analytical aspects.     

Gas-liquid separator with integrated manifold as interface for HPLC-hydride AAS of organotin compounds

Summary A gas-liquid separator is presented, which is adapted to the special conditions of metalorganic speciation analysis by HPLC-hydride AAS.     

Continuum source atomic absorption spectrometry and detector technology: A historical perspective

The close relationship between the development of Continuum Source AAS (CS AAS) as a technique for element analysis and the availability of suitable detectors is reviewed, beginning with the photoplate and culminating in state of the art Charge-Coupled Devices (CCDs). The review is organized to follow the historical sequence of development but emphasizes in particular the appropriateness of detector technologies to the development for simultaneous and sequential CS AAS techniques. The essential role of certain aspects of detector performance is elucidated and it is shown that since only solid-state CCD detectors have become available can competitive CS AAS instrumentation be realized.     

Trends in selenium determination/speciation by hyphenated techniques based on AAS or AFS

The field of selenium speciation has been studied for decades and the growing interest in this field seems never to reach a plateau. Although powerful techniques based on mass spectrometry are nowadays used for selenium determination/speciation, few laboratories can support the high cost of such techniques. The hyphenation of chromatography to atomic absorption or atomic fluorescence spectrometry (AAS or AFS) is still a reliable and low-cost alternative for routine laboratories. In this work we present the most important parameters dealing with selenium speciation along with the latest trends in this subject, namely in the items related with sample treatment and hyphenation techniques with AAS and AFS detection.