8260: everything good but PCE

[MichaelVW]

Hi everyone,

The short story is that a couple days after calibrating, my CCV looks great for every compound except tetrachlor. After one to two days it's down to ~70% and then it decreases from there.

I've got a 6890/5973, using an Archon auto sampler and 4560 purge & trap. I've tried leak checking, cleaning the source, clipping column, replacing the liner and gold seal, cleaning the sparge tube, using a new filament, and replacing the trap.

I tune using the modified autotune in this document: https://www.agilent.com/cs/library/Supp ... f05011.pdf

My initial PCE (m/z 166) response factor vs. chlorobenzene d5 is about 0.6

I calc off the primary ion but also looks like PCE's secondary and tertiary ion response decrease over time. 1,3-dichloropropene seems to coelute with it (I don't calibrate/analyze for this compound).

Other heavy chlorinated compounds like 1,1,2,2-tetrachloroethane are fine.

I am manually adding IS and Surrogate to my VOA vials because there seems to be a problem with our autosampler that I haven't tracked down yet either. The IS and Surrogate solutions seem to be escaping... it's normal for me to see them concentrate down a little over time, but I lost about 1 mL out of 4 mLs of methanol even with both standard vials turned off. (No signs of a leak right at the neck of the vials though.)

I'll come back and add anything I think of. But at this point I'm not sure what else to check or try. Any suggestions?

[James_Ball]

For the loss of IS solution, you probably need to replace the vespel rotor in the valve, those tend to leak on the old Archons. If they wear really bad you might have to replace the whole valve, but normally it is just the rotor in the center that measures the 1ul volume that wears and leaks.

For loss of tetrachloroethene, it can happen when the transfer line or other heated lines in the flow path get contaminated, especially with salt residues. You can disconnect the transfer line and attach an adapter and syringe to it and push water then methanol through the line and sometimes remove the contamination, but often you have to replace the whole line. This usually happens after a sample foams and pushes particulates over into the system. It was especially bad if you have the nickle transfer line, the silcosteel ones are not quite as bad, and the most resistant is just plain 0.53 megabore fused silica transfer line.

[MichaelVW]

Thanks, James! I rinsed out the transfer line like you said and the problem went away!

[James_Ball]

Thanks, James! I rinsed out the transfer line like you said and the problem went away!

Glad it was the simple fix!