SREL Reprint #2092
chapter twenty-six
Measuring metals and metalloids in water,
sediment, and biological tissues
Michael C. Newman
Introduction
Outbreaks of cadmium (Itai-Itai disease) and mercury (Minamata disease)
poisoning during the 1950s made us acutely aware of the adverse consequences
of high concentrations of metals in our environment. Quickly, measurement of
metals and metalloids became an integral component of our efforts to monitor and
correct effects of anthropogenic emissions. The widespread introduction of
commercial atomic absorption spectrophotometers (AAS) in the early 1960s
contributed enormously to the rapid increase in essential data.
The first quantitative AAS was developed in the 1940s. The number of
commercial AAS units was increasing exponentially by 1963. The introduction of
flameless atomization methods lowered limits of detection several orders of
magnitude by allowing the ground state metal to stay in the analytical fight path
longer than with flame aton-dzation. Today flame and flameless capabilities are
incorporated together in AAS units, allowing convenient measurement of elements
present in mg/g to µg/kg concentrations. Well-established, preconcentration
procedures are used to remove analytes from interfering matrices as well as to
concentrate them in small volumes. Flame and furnace chemistries are now
sufficiently well understood to allow effective matrix modification for most
elements.
Although measurement of metal concentrations has become routine and
convenient, considerable work remains to be done relative to assessing metal
bioactivity and speciation. Numerous sample pretreatments exist that imperfectly
reflect bioavailable metal. Discussed in detail, such methods and associated
assumptions would easily fill an entire book. Further, the rapid changes in this area
of metal ecotoxicology would make such a volume obsolete within a few years.
Consequently, only the most fundamental techniques for measuring metals
dissolved in waters, or present in solid samples are described here. Hopefully,
these methods will have the most general utility. Space limitations also exclude
adequate description of the cold vapor methods for mercury and
hydride-generation methods for arsenic or selenium.
SREL Reprint #2092
Newman, M.C. 1996. Measuring metals and metalloids in water, sediment and biological tissues. p. 493-516. In Techniques in Aquatic Toxicology, edited by G.K. Ostrander. CRC Press. Boca Raton, FL.
