Tue Feb 11, 2020 7:06 pm by mleipold
Hi Terry,
Short answer: I'm not sure. Concentrated nitric would do the best job of dissolving everything down to components (ie, avoiding clumps and stuff). And since you're probably going to need to dilute 100-fold or more to be in a good measurement range, this would still drop your nitric concentration to <1% v/v (remember, Tuning solution is 2% v/v).
However, just using 2% nitric (or even Tuning solution) would probably be fine: if you start running either of those, residual material in the instrument goes from punctate "events" to streaks......at a minimum, this indicates that the metal is being released from the cells. Maybe 15-20min at 37C (probably longer than needed, but just to be sure).
If all you care about is the Ba138 signal, then Tuning solution might be a good way to go about it: you'd have the La139 signal and the other signals as references for intensity. Formally, this would be adjusted by whether Ba138 ionizes in the plasma as efficiently as the Lanthanides (it seems like it would be at least very close), but if you're just looking for fold-differences between "Good" and "Bad" Ba138 samples, it wouldn't matter since you'd be standardizing as "signal from the Ba138 content in 1M cells" or whatever.
Mike