AAS Lead

Atomic Absorption Spectroscopy & Lead Contamination of Water

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Lead in Drinking Water

Lead exposure causes damage to the brain, kidneys, nervous system, and red blood cells

Young children and pregnant women are at the greatest risk

Drinking water, paint, dust are common lead sources
Lead pipes, corroded brass fixtures, and lead solder can introduce lead into drinking water

Limiting Exposure

Flush pipes every 6 hours for up to 2 minutes
Use cold water for consumption

Testing

EPA advises a level no higher than 15 ppb, especially if there are young children in the household
Individuals use independent labs for testing of home samples
Several types of atomic absorption spectroscopy (including graphite furnace) are EPA approved methods.

Atomic Absorption Spectroscopy

Gas phase sample absorbs UV or visible light causing transitions to higher electronic energy levels

Absorption of light is correlated to concentration using the Beer Lambert Law:
                A = -log(I/I_o) = εbc
            ε= molar absorptivity (L/mol*cm)
            b=path length of sample cell (cm)
            c=concentration of compound (mol/L)
        I_o = initial intensity        I = final intensity

Block Diagram of Atomic Absorption Spectrometer including
light source (hollow cathode lamp), monochromator, and detector
source: http://www.chemistry.nmsu.edu/Instrumentation/AAS.html

Instrumentation

Light Source: Excitation of Sample

Atomizer: Flame or gas furnace is used to vaporize sample

Monochromator: allows for isolation of absorption line

Light is detected, converted to electrical signal, and amplified

Experimental Results

Atomic Absorption Spectra of a dried blood sample showing peaks for lead, iron, and zinc found in the sample (Karai et. al. 1981)

Improvements

Preconcentration of water samples has been used in order to detect lead easier in samples less than 50 ug/L. (Foreback 1997)

Future Uses

Similar methods can be used for analysis of lead in blood samples. (Parsons and Slavin 1993)

References
C. C. Foreback, J. Chu. "Measurement of Lead in Drinking Water by Atomic Absorption Spectrometry with Dithizone Extraction." Toxicological & Environmental Chemistry (1997). 63:163-170.

Karai, I. and Fukumoto, K. and Horiguchi, S. “Improvement in the atomic absoroption determination of lead in blood.” Journal of Applied Toxicology (1981): 295-296

P. J. Parsons, W. Slavin. "A Rapid Zeeman Graphite Furnace Atomic Absorption Spectrometric Method for the Determination of Lead in Blood." Spectrochimica Acta Part B: Atomic Spectroscopy (1993). 48: 925-939.

http://www.caslab.com/EPA-Methods/?term_search=&page=3&definition_search=

http://www.epa.gov/safewater/lead/lead1.html

http://www.files.chem.vt.edu/chem-ed/spec/atomic/aa.html