Development and some applications of techniques for the determination of trace metals by furnace atomic absorption spectrometry

The role of the analytical chemist is considered with respect to the impact of new trace analytical techniques on environmental science. Reference is made to the role of atomic absorption spectrometry (AAS), particularly furnace AAS, anodic stripping voltammetry (ASV) as an alternative to the latter and important factors influencing precision and accuracy in trace analysis. Application of trace analysis techniques to study atmospheric elemental particulates (distinct from volatile molecular species) and important related factors are reviewed. Supporting data from studies using high volume particulate sampling and flame AAS methods were undertaken to provide comparative data for studies indicated below. Micro-air sampling techniques based on furnace AAS were improved and further developed into routine methods for particulate collections (Pb, Cd, Zn, Cu) using graphite cups (with inserted discs of Millipore membrane and graphite cups alone) as air-filtration device and simultan~ eous furnace atomizer. Emphasis was placed on the identification and elimination of contamination using a modified procedure and use of an alternative practical graphite cup sample container system. Other factors investigated were the physical properties of graphite cups and associated collection devices, nature of particle penetration through various filter media anrl significance of meteorological parameters. Unique studies undertaken covered the spectrum of particulate levels likely to be found (elements indicated as particulates in aerosols containing <100 to >10 (to the power) 8 total particles cm- 3). These include the time variation of Pb atmospheric particulates in urban and baseline conditions, identification of source types by time variation with wind speed and direction, short term measurement and time variation of atmospheric Pb as \fall-out\" and the direct measurement of Pb and Cd in cigarette mainstream smoke. from single cigarettes. The overall applicability of micro-air sampling techniques for elemental particulate measurements is summarized with respect to the contents of the given review. The role of trace analytical techniques for the determination of trace elements in biological systems is considered with particular reference to furnace AAS and the determination of the elements Pb (nonessential) and Cu (essential) in blood. Furnace AAS methods for Pb and Cu based on blood solutions in 5% Triton X-100 (from a method described for Pb 'in blood) were developed and evaluated through studies of accuracy and precision. Comparison with the alternative technique ASV was made for Pb. The blood Pb method was applied to survey levels in Hobart dogs· and cats and indicated dogs were potential environmental Pb monitors. The blood Cu method was applied to survey children and adults from Hobart and environs and showed the possibility of pin-pointing individuals (categorized as healthy) with certain physiological and pathological conditions. A fundamental study concerning the nature of high temperature molecular species with respect to- furnace AAS was undertaken using Raman spectrometry. A high temperature furnace (of unique design) was constructed based on a Perkin Elmer HGA-70 \"Heated Graphite Atomizer\" to permit recording of Raman spectra (Cary 82 laser Raman spectrometer Ar+ excitation) of the vapours from Zn Cd Pb halide and phosphate systems (individually and mixed with alkali halides) in sealed silica tubes and over a temperature range 300-ll00°C. Interpretations in terms of vapour species lost during drying ashing and atomize furnace AAS cycles are made with special reference to vapour complex formation. The use of the Raman spectrometer as detector to measure molecular concentrations (technique analogous to furnace AAS) based on properties' of the Raman and associated effects is proposed."