ICP-AES Argon

[rdd]

if argon is not being used for the optics purge, what are the issues with
argon purity in the torch plasma? What happens if a low grade is used?

[Marvin]

Post by rdd
if argon is not being used for the optics purge, what are the issues with
argon purity in the torch plasma? What happens if a low grade is used?

It depends on the sample composition and the impurities.
Reactions will take place between the spray particles and
the gas, and some refractory compounds can form that affect
the vaporization of the particles. Some compounds may form
after volitalization that emit molecular bands, which can
cause spectral interference. These phenomena are well known
from dc arc spectroscopy.

[Samite Alchemist]

Main problem with impure argon: Plasma will not light.

Samite Alchemist

[Marvin]

Post by Samite Alchemist
Main problem with impure argon: Plasma will not light.
Samite Alchemist

That is interesting. I can't think why it should happen,
unless there is a lot of water vapor in the gas.

[Sassman]

Post by Samite Alchemist
Main problem with impure argon: Plasma will not light.
Samite Alchemist

That is interesting. I can't think why it should happen, unless there
is a lot of water vapor in the gas.

I have also wondered the reason for this, but have heard it from several
sources so I assume it is true. Personally, all of my problems with the
torch not lighting have been due to bad o-rings or other leaks in the
torch itself.
---
www.analyticalchem.com

[Michael Cain]

I think it's the RF tuning circuit which can't cope with impure argon -
possibly too much reflected power? Like others, most plasma problems
I've had have been air leaks, damp or cracked torch or glassware, but I
have had dirty torches and corroded earth return circuit components.
Doing all the routine maintenance procedures, even when there are urgent
samples waiting,and rotating torches with one in use and one being
cleaned can help. If you change the torch every week, it is easier to
spot leaks, stretched 'O' rings and dirty coils etc, as well as making
you more at ease with the expensive grey box!

Mike

Post by Sassman

Post by Samite Alchemist
Main problem with impure argon: Plasma will not light.
Samite Alchemist

That is interesting. I can't think why it should happen, unless there
is a lot of water vapor in the gas.

I have also wondered the reason for this, but have heard it from several
sources so I assume it is true. Personally, all of my problems with the
torch not lighting have been due to bad o-rings or other leaks in the
torch itself.
---
www.analyticalchem.com

[Samite Alchemist]

Original question was
"if argon is not being used for the optics purge, what are the issues
with
argon purity in the torch plasma? What happens if a low grade is
used? "

The impurities in low grade argon (oxygen, water, hydrocarbons) hinder
argon from achieving a stable plasma. That does not mean bad argon is
the _most common_ reason for bad ignition! If the question had been
"What are the most likely causes of unsuccessful ignition?", bad argon
would be pretty far down. Uncommon, but it does happen.

Samite Alchemist

Post by Sassman

Main problem with impure argon:  Plasma will not light.
Samite Alchemist

That is interesting.  I can't think why it should happen, unless there
is a lot of water vapor in the gas.

I have also wondered the reason for this, but have heard it from several
sources so I assume it is true. Personally, all of my problems with the
torch not lighting have been due to bad o-rings or other leaks in the
torch itself.
---www.analyticalchem.com