Torch meltdown cause


I've just experienced a torch meltdown on a 5800 ICP-OES with an easy fit torch, while trying to heighten the plasma robustness using the Mg II/Mg I method.

To begin, colleagues of mine ran an intelliquant screening on unknown sample last friday that was very high in Boron and sodium levels and should have been dilluted. We haven't done any calibration for our intelliquant so the actual concentrations are unclear, but since even the weakest emission lines give a strong signal, i'm assuming it was still way too high.

When i got back on monday i noticed a white residue on the upper part of the torch. I tried cleaning the torch with 50% aqua regia for 2 hours. Since that did not work i tried 70% aqua regia, for 2-3 hours. Sadly this also did not remove the residue, i also tried a very diluted laboratory detergent with no result.The always helplful mentoined elsewhere on this forum that the residue might actually be devitrification of the quartz glass and i think this is actually the case. See the pictures below.

Since we did/do not have a spare torch on hand we settled on installing the torch again until our new torch would arrive. When trying to resume my plasma robustness tests earlier this week i noticed that the same exact settings resulted in about half of the Mg II/ Mg I ratio (from 6.47 to around 3.50, both far from robust). Could this be a result of the devitrification or should i look elsewhere to explain this? The settings in question were:

RF power: 1.5 kW
Neb flow: 0.5 L/min
Plasma flow: 10 L/min
Aux flow: 1 L/min

Today i continued with the plasma robustness and when i used the following setttings for about 30 seconds the meltdown occured:

RF power: 1.5 kW
Neb flow: 0.5 L/min
Plasma flow: 8 L/min
Aux flow: 2 L/min

I am trying to find out if the meltdow was caused either solely by the settings or the devitrification, or if it was probably a combination of both. Any help/suggestions are very welcome :)

Thanks in advance!

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