Background Correction
Definition
A method (deuterium continuum, Zeeman effect, Smith-Hieftje self-reversal, or high-resolution continuum-source) that subtracts non-atomic absorption (molecular bands, scatter) from the raw absorbance to leave only the atomic signal.
- Field
- Atomic absorption spectrometry
- Common methods
- Deuterium continuum, Zeeman, Smith-Hieftje, HR continuum-source
- What it removes
- Molecular absorption bands and light scatter
Common questions
Why does AAS need background correction at all?+
The sample matrix can absorb or scatter light at wavelengths close to the analyte line through molecular species and particulates in the flame or furnace, which inflates the apparent absorbance if left uncorrected, so background correction isolates the true atomic signal from this matrix interference.
How does the Zeeman method differ from deuterium background correction?+
Zeeman correction applies a magnetic field to split the atomic absorption line and measures background at wavelengths where the atomic signal has shifted away, which corrects accurately even for structured background close to the analyte line. Deuterium correction instead subtracts a broadband continuum-source measurement and can under-correct when the background itself has fine structure.
When is background correction most critical in forensic casework?+
It matters most in graphite furnace AAS on complex matrices such as gunshot residue digests, tissue or hair samples, where organic matrix components and salts commonly produce non-atomic absorption that would otherwise be mistaken for the trace metal being quantified.
Related terms
- AAS
- Atomic absorption spectrometry. Free ground-state atoms in a vapour absorb a characteristic resonance wavelength from a hollow-cathode lamp, and Beer-Lambert converts the...
- CVAAS
- Cold-vapour AAS. Mercuric ions are reduced by stannous chloride or sodium borohydride to elemental mercury vapour, swept by argon into a quartz...
- GFAAS
- Graphite-furnace AAS, also called electrothermal AAS. A graphite tube heated electrically through a programmed ramp atomises a microlitre aliquot, giving roughly 100...
- HG-AAS
- Hydride-generation AAS for hydride-forming elements (As, Sb, Se, Bi, Te, Sn, Ge). Sodium borohydride in acid generates the volatile hydride, which is...
- Hollow Cathode Lamp (HCL)
- A sealed lamp whose cathode is made of the element being analysed, filled with argon or neon at low pressure. Strikes a...