I have run into a situation where I detect sodium when running a potassium standard.

The method forces me to check my potassium standard with both potassium and sodium lamp (some kind of specificity test I guess).

The preparation of standard has been repeated by several persons, and a freshly opened (purchased) standard has been used to exclude the obvious answer contamination.

- When using the potassium lamp I get an Abs of about 0,490 in the potassium standard

- When using the sodium lamp I get an Abs of about 0,060 in the potassium standard

This signal is a fair bit above the blank and I had suspected that it would be about zero...

Has anyone experienced something similar?

Thankful for input!