Application of Atomic
Absorption Spectroscopy for Monitoring
Selected Metals in an Industrial Waste
ALFRED M. TENNY, Research Chemist
GEORGE H. STANLEY, Sanitary Chemist
The Metropolitan Sanitary District of Greater Chicago
Chicago, Illinois
INTRODUCTION
Atomic absorption has been shown to be a valuable analytical aid in many
fields. Numerous articles have been published describing methodologies for over
70 elements in various matrices and in the presence ofdifferent interferences.
New applications and techniques are continuing to be found. Within the Metropolitan Sanitary District of Greater Chicago, atomic absorption is used for a variety of samples. These vary from trace determinations in water samples to metallic constituents in lubricating oils.
In the monitoring of industrial waste water samples the usefulness of atomic
absorptions has exceeded our most optimistic expectations. Iron, manganese,
zinc, cadmium, copper, nickel, chromium and lead were measured routinely and
rapidly on all industrial waste water samples during a period of over two years. In
addition, calcium, magnesium, sodium, potassium, lithium, tin, cobalt, silver
and molybdenum have been measured in various special samples with little difficulty.
Atomic absorption is especially well suited to industrial waste analyses for
several reasons. These include simple sample preparation, relative absence of interferences, ease of operation, optimum sensitivity for most metals of interest
and low cost per analysis. When one considers alternative methods of measuring
trace metals, as given in Standard Methods (1), atomic absorption looks even
better. This is especially true if one is required to analyze a large number of
samples. The District has analyzed as many as 400 samples per instrument per
day. Instrument time has never been a limiting factor in the industrial waste
monitoring program. Prior to the application ofatomic absorption, the analyses
of "heavy metals" were a constant laboratory bottleneck. Both the number of
samples and the number of parameters per sample were extremely limited by
available manpower and space. We shall attempt to show how atomic absorption
is applied in waste water monitoring and how intensive data evaluation can expedite a pollution control program.
EXPERIMENTAL PROCEDURE
The most important step in any analysis is sample collection. This is especially true in pollution control where laboratory results must be available for legal
action. The present group of Industrail Waste Ordinances (1946, 1962) limit,
among other parameters, the discharge of toxic materials by industry to sewers,
streams and drainage areas. Analytical results must be based on composite sewer
samples which are taken "over a 24-hr or longer period from the flow from all
plant outlets discharging into a single public sewer" (2).   Stream drainage area
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