Graphite Furnace Atomic Absorption Spectrometry

Graphite furnace atomic absorption spectrometry (GFAAS) is also known as electrothermal atomization atomic absorption spectrometry (ETAAS). GFAAS is an established technology for quantifying elements at trace and ultra-trace levels (down to low μg/L) while using only small sample volumes (usually less than 100 μL).

In GFAAS, a known amount of sample solution is injected into a graphite- or pyrolytic carbon-coated graphite tube, which can then be heated to vaporize and atomize the analyte. The atoms absorb ultraviolet or visible light of an element specific wavelength and make transitions to higher electronic energy levels. The amount of absorption is a measure for the concentration of the element of interest in the sample solution. Concentrations can be derived after calibrating the instrument with standards of known concentration.

Ideal uses of GFAAS

Trace metals in ultra-pure water
Determination of SiO₂ in ultra-pure water with a detection limit of 0.4 μg/L

Strengths

Good sensitivity
Low detection limits (μg/L)
Applicable to a wide variety of matrices
Small sample volumes
Limited spectral interferences

Limitations

Time consuming
Sequential analysis of 1-6 elements
Limited dynamic range (= range over which ion signal is linear with analyte concentration)
No screening ability
Separate method optimization required for each type of sample

GFAAS Technical Specifications

Sample amounts: 1 mg (solids), 1 mL (solutions)
Quantitative/Qualitative: quantitative
Destructive/non-destructive: destructive
Sample (pre)treatment: dissolution of the sample
Detection limit: μg/L in solution