[usm_comm]

Hi everyone,

New guy here.

I injected some Deoxit, the product used to clean electric contacts, into a GC/MS. Well, first up, the conditions:

Instrument: HP 6890N with 6890 injector.
Column: Phenomenex Zebron ZB-5ms
Detector: Agilent Technogies 5793 Mass Selective Detector
Instrument conditions: Inlet Split 50:1, 250°C; Column init temp 50°C hold 5 min, 10°C/min to 250°C hold 10 min; Carrier gas Helium, 26cm/s per Van Deemter optimal
Detector conditions: Evaluated mass 50 - 500 g/mol, eluent hold 2.00 min, scan 3.75/s

The injected Deoxit was taked directly from the spray can with no dilutions.

The first compound seen by the MS is http://www.chemspider.com/Chemical-Structure.68090.html with a certainty of 913/1000.

Next up, however, the MS started to see multiple cyclic siloxanes. These siloxanes have 3 to 6 Si per molecule. From what I know, this is a sign of column backbiting but after some searches, siloxanes are also used in some lubricants. I did see the baseline start to rise by the end of analysis.

My questions related to this analysis are:

* Seeing how Deoxit advertises the "de-oxidize" function, could there be a non-volatile reducing agent in Deoxit that did not pass through the column?
* Are those cyclic siloxanes really from Deoxit itself or are caused by column backbiting?

Thank you all very much!

[Stepan]

I checked MSDS's. The products I found show 70-90% of chlorinated of fluorinated compounds. It is likely that you overloaded the system. Dilute your sample 1/100 in methanol.