Maybe I can add something to this.
We use a NWR UP213 coupled to Agilent 7500ce, He is delivered to the
laser from the 7500, we use the optional gas flow controller of the
ICP-MS. The plasma on procedure is a bit complicated, but it works every
- connect everything for LA work (tubings for gases and sync out cable),
put a sample in the ablation cell.
- open tune window in ICP-MS, load the tune file for LA work, set the
optional gas (He) to 100%
- put the LA valves in bypass and online setting for at least 2 minutes
each (to flush the tubes and valves),
- put the LA to purge setting for some 5 minutes,
- set the He gas flow (optional gas in the ICP-MS tune window) to 10% -
DO NOT PUT TO 0%!! this is essential!
- switch the plasma on, the laser valves setting has to be on purge
during plasma being lit,
- when the ICP goes to analysis mode, switch back to tuning window,
- change the LA valves to online,
- slowly increase the optional (He) gas flow to the setting used.
Basically, when transitioning form the standby to analysis mode, ICP at
some time changes all the settings to those, set in the tune file. At
this time, He flow controller opens (and overshoots the setting) and in
this moment it will almost surely blow the plasma off if the LA valve
setting is in bypass or online. Have the valves on purge - He blows out
at the back of the LA unit and not to the torch.
I hope this helps.
dr. Vid Simon Selih,
LA-ICP-MS lab manager,
Analytical Chemistry Laboratory L-04,
National Institute of Chemistry, Slovenia
Hajdrihova 19, Ljubljana, Slovenia
E: [log in to unmask]
Barnes, Melanie wrote:
> We run our helium at 600ml/min and our argon at 1.26L/min. We also have a very careful start up procedure in order to avoid putting out the plasma. I have given a quick version below...
> disconnect the tubing from the laser to the torch at the glass connector, turn the argon flow on at 2L/min, turn the helium flow on at 1000ml/min, purge the laser 5x, after the purges allow gas flow for about one min, then turn argon off and helium to 200ml/min, reconnect the tubing to the glass connector (we find this part cleans out the tubing and warm up time is decreased)
> light the plasma with helium on at 200ml/min, once the plasma is lit and stable slowly increase the helium by 100ml/min until you reach 600ml/min, the mass flow controller should reach the right flow before you go to the next 100
> we don't usually have a problem with the plasma going out even when we do a sample change (the laser is put on bypass and we purge 5x once the new sample is loaded, our plasma seems to be able to handle the change from flow with helium plus argon to just argon and then back
> Good luck, Melanie
> PS we have a NewWave 213 and a 7500cs Agilent
> Dr. Melanie Barnes
> Geosciences/ Texas Tech University
> Lubbock TX 79409-1053
> 806 928 1098
> 806 742 0100 (fax)
> [log in to unmask]
> From: PLASMACHEM-L: Analytical Chem.(ICP's, DCP's, MIP's). [[log in to unmask]] On Behalf Of Ryan Bu [[log in to unmask]]
> Sent: Monday, December 06, 2010 3:26 PM
> To: [log in to unmask]
> Subject: LA-ICPMS
> Hey guys, just wodering if anyone had encountered a plasma issue like this: we coupled laser ablation unit with icpms by a T, Heluim was used as laser carrier gas, as long as the flow went 500ml/min or higher, in about 10 -20mins, the plasma was put off... the sample gas for ICPMS was 1.02l/min, just cant figure out why the plasma was put off, if it was because of the high flow He, shouldnt it be put off right after the flow was ramped up? Thanks
> Ryan Bu
> Univ of Mississippi
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