K and Na on 7900

Yes you can analyze sodium in No Gas mode (unless you also have an enormous amount of Li in your sample :-)).

For potassium you need He or H2 mode because there is a lot of Ar interference in No Gas mode. And you can't make an interference equation for that.

In nogas mode, a large number of bivalent ions will contribute to Na, which can be tried by increasing the sampling depth, increasing the carrier gas flow, and reducing the plasma energy. But it is conceivable that the BEC will not be low.

K is because of the large amount of interference of Ar+H, and He, H2 can be used to reduce the influence of Ar+. H2 mode is recommended.

Hi, 

You can also try to measure Na and K in cool plasma conditions. If your software don't have that option you can modify no gas mode - reduce RF power to 600W, increase Smpl Depth to about 18mm and start signal monitor to adjust rest of the parameters. You schould be able to determine Na and K down to 1ppb or lower with cool plasma conditions.

Good luck, 

P.