Atomic Absorption Spectroscopy & Lead Contamination of Water

Dowload this lesson


Lead in Drinking Water
Limiting Exposure
Testing

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/Io) = εbc
            ε= molar absorptivity (L/mol*cm)
            b=path length of sample cell (cm)
            c=concentration of compound (mol/L)
        Io = initial intensity        I = final intensity

klhlk
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

Future Uses



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