DETERMINATION OF TRACE METALS IN ENVIRONMENTAL SAMPLES BY MICRO ATOMIC ABSORPTION SPECTROMETRY WITH SOLID SAMPLE INTRODUCTION

Abstract

Atomic spectrometric techniques are in widespread use for determining trace metals in many sample types. A major disadvantage, however, is the need generally to present samples in a liquid form to the instrument. Common sample preparation procedures are dry ashing followed by dissolution of the inorganic residue in dilute mineral acid or wet digestion with oxidizing acids. Dry ashing is slow and may lead to losses of volatile elements, and wet digestion is hazardous, often requiring treatment with hydrofluoric and perchloric acids to completely dissolve the matrix. Previous work in this laboratory led to the development of a rapid microsampling-cup atomic absorption method for determining lead in vegetation. The dried vegetation was powdered and made into an aqueous slurry which was pipetted directly into the sampling cups. No further treatment was required prior to sample atomization. This work has been extended to enable very small segments (a few mg) of a plant to be analyzed individually. The modified analytical technique will be described and it will be shown how the distribution of lead, at normal levels, through a single plant can be determined. Preliminary results demonstrated that lead can be determined in soil by introducing slurries directly into a graphite furnace electrothermal atomizer. Further work will be presented to show that good correlation with a total digestion procedure (hydrofluoric/perchloric/nitric acids) is achieved. The technique is being applied to determinations of other metals, and results obtained for various soil types will be presented.

This issue of the journal was a special issue presenting the abstracts of the papers presented at Colloquium Spectroscopicum Internationale, Amsterdam , 1983

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160 JACKSON (P-37)
DETERMINATION OF TRACE METALS IN ENVIRONMENTAL SAMPLES
BY MICRO ATOMIC ABSORPTION SPECTROMETRY WITH
SOLID SAMPLE INTRODUCTION
K.W. Jackson, I.W. Eastwood and A.P. Newman
Department of Chemistry, Sheffield City Polytechnic, Sheffield Sl lWB, U.K.
Atomic spectrometric techniques are in widespread use for determining trace
metals in many sample types. A major disadvantage, however, is the need
generally to present samples in a liquid form to the instrument. Common
sample preparation procedures are dry ashing followed by dissolution of
the inorganic residue in dilute mineral acid or wet digestion with oxidiz-
ing acids. Dry ashing is slow and may lead to losses of volatile elements,
and wet digestion is hazardous, often requiring treatment with hydrofluoric
and perchloric acids to completely dissolve the matrix.
Previous work in this laboratory (1) led to the development of a rapid
microsampling-cup atomic absorption method for determining lead in vegeta-
tion. The dried vegetation was powdered and made into an aqueous slurry
which was pipetted directly into the sampling cups. No further treatment
was required prior to sample atomization. This work has been extended to
enable very small segments (a few mg) of a plant to be analyzed individually.
The modified analytical technique will be described and it will be shown
how the distribution of lead, at normal levels, through a single plant can
be determined.
Preliminary results demonstrated that lead can be determined in soil by
introducing slurries directly into a graphite furnace electrothermal atom-
izer (2). Further work will be presented to show that good correlation
with a total digestion procedure (hydrofluoric/perchloric/nitric acids)
is achieved. The technique is being applied to determinations of other
metals, and results obtained for various soil types will be presented.
References
1. K.W. Jackson, L. Ebdon, D.C. Webb and A.G. Cox, Anal. Chim. Acta, 128,
67 (1981).
2. K.W. Jackson and A.P. Newman, Analyst, in press (1983).