Oil Prep for ICP?

[Cyclops]

Is there a common procedure for preparing motor oil for ICP analyis? Is it broken down with a peroxide or acid?

Doug

 

[edhackett]

It would appear that simple dilution with kerosene is the most common method of sample prep.

Here's one link: http://cp.chem.agilent.com/Library/applications/Icpes-13.pdf

Ed

 

[Cyclops]

Thank you Ed. I'm surprised kerosene is used. I would have thought it would be too energetic and swamp the spectral light analyzer. I also thought it was interesting that there is analytical grade kerosene and deodorized too!

Doug

 

[edhackett]

The plasma runs at ~10,000 degrees Kelvin. The hydrocarbons are broken down to ionized C and H, it doesn't "burn", so only those emission lines are present. The optical system is very tightly controlled, so unless the emission lines fall right on, or within the slit width of your element of interest it doesn't cause any problem.

Ed

 

[Cyclops]

In that case Ed, why not simply inject the oil without kerosene dilution?

 

[edhackett]

There are a couple of reasons that I can think of off the top of my head. First is to reduce the viscosity. The sample has to be atomized to droplets less than 5 microns to be aspirated into the plasma. The viscosity of the sample and standards must match. Second is to dilute the metals of interest within the linear range of the instrument.

Ed

 

[Cyclops]

Thanks Ed, makes good sense!

Doug