Ashing Aid
Definition
A salt (typically magnesium nitrate) added before dry ashing to fix volatile elements as less volatile salts that survive the furnace.
- Typical reagent
- Magnesium nitrate
- Applied
- Before dry ashing
- Purpose
- Fixes volatile elements as less volatile salts
Common questions
Why would an element need to be fixed before ashing rather than measured directly from the sample?+
Some metals and metalloids, arsenic and mercury among them, can volatilise and escape as the furnace temperature rises during dry ashing; converting them to a less volatile salt beforehand keeps them in the residue for later analysis.
Does using an ashing aid change which analytical method is used afterward?+
No. The aid only protects analyte recovery during the ashing step itself; the resulting inorganic residue is still dissolved and analysed by the same downstream methods, such as atomic absorption spectroscopy, as any other ashed sample.
Related terms
- Acid Blank
- A parallel digestion of reagents in an empty vessel, subtracted from the sample to correct for trace metal contamination in the acids.
- Dry Ashing
- Viscera or hair is dried and incinerated in a muffle furnace at 450 to 550 degrees Celsius. Inorganic ash is dissolved in...
- Matrix Destruction
- Breakdown of organic tissue into water, CO2 and mineral residue so bound metals are released as free ions. Without it, AAS reads...
- Microwave-Assisted Digestion
- Closed-vessel digestion in PTFE or quartz bombs at 1200 to 1800 W, reaching 200 degrees Celsius and 1500 psi in 30 to...
- Wet Digestion
- Viscera is digested with HNO3 + H2SO4 + HClO4 (or HNO3 + H2O2) at controlled temperature. Closed-vessel microwave-assisted digestion in Teflon bombs...