CVAAS
Definition
Cold-vapour AAS. Mercuric ions are reduced by stannous chloride or sodium borohydride to elemental mercury vapour, swept by argon into a quartz absorption cell at 253.7 nm. The standard mercury method.
- Expansion
- Cold-Vapour Atomic Absorption Spectrometry
- Reducing agents
- Stannous chloride or sodium borohydride
- Analyte
- Elemental mercury vapour
- Wavelength
- 253.7 nm
- Carrier gas
- Argon
Common questions
Why does mercury need its own AAS technique instead of flame or graphite furnace AAS?+
Mercury is unusual among metals in having significant vapour pressure at room temperature once reduced to its elemental form, so it can be swept as a cold vapour directly into the absorption cell without needing a flame or furnace to atomise it.
What sample types is CVAAS commonly used on in forensic toxicology?+
It is applied to blood, urine, tissue, and hair digests when mercury poisoning or occupational exposure is suspected, since it offers very low detection limits for this specific element compared to general multi-element techniques.
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...
- Background Correction
- 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...
- 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...