Mike,



You are apparently doing what might best be described as an "incomplete" digestion, or a partial extraction.  The result is that every time your acid-containing rinse hits it, you denature more protein, which agglomerates and clogs.  The nebulizer you use will make no difference; it is just preventing clogs in your spray chamber drain - which will eventually happen.



You can't have any acid, as Steve Pappas points out, in your rinse solution.  Any change in pH, no matter how briefly, stuff is going to come out of solution.  Bob Taylor also points out the probability of forming a chelating chromatography column in your transfer tubing. 



Your rinse should contain DI water and a nonionic surfactant like Triton X-100.  No acid; no base (TMAH).  Or do the complete digestion.



Let me tell you about a really bad experience maybe 25 years ago where a lab was trying to analyze "partially digested urine" in an overnight run when they actually clogged the spray chamber drain, and there was no plasma detection circuit, so when the plasma went out, the gases, pump, and autosampler kept running all night long raining you-know-what all over the instrument and the lab.  The operator was a mite peeved the following morning.



Geoff





Geoffrey N. Coleman, Ph.D., President

MEINHARD

Elemental Scientific Glassblowing, LLC.

700 Corporate Circle, Unit L

Golden, CO 80401-5636

Tel: 303-277-9776 Fax 303-279-5156

www.meinhard.com

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-----Original Message-----

From: PLASMACHEM-L: Analytical Chem.(ICP's, DCP's, MIP's). [mailto:[log in to unmask]] On Behalf Of Michael Ruhlman

Sent: Wednesday, March 01, 2017 8:30 AM

To: [log in to unmask]

Subject: Re: Signal Decrease then Jump



It definitely looks like the nebulizer was causing some problems.  I put it under the microscope and am pretty sure I see build up.



I am going to try a Sea Spray nebulizer to see if that will help some.  Does anyone have experience with a pre-treatment of the nebulizer or a wash solution that could help clear any protein build up?