Chromatography Forum

Hi everybody,

We have to analyze some nylon filter for content of mineral oil. The mineral oil comes from the air compressor and should be composed by alcane (C16 and more..). We have found a method (NIOSH 5026) where the mineral oil is extracted by CCl4 and analyzed by IR. Unfortunately we don't have access to an IR instrument..
It could be possible to extract the mineral oil from the filter and inject the extract on a GC-FID (on-column) to quantify the concentration? Do you see some limitation on this approach that we don't see?
What solvent is usually used to extract mineral oil from nylon filters instead of CCl4?
Do you have some reference on the analysis of mineral oil mist on nylon filters?

Thank in advance for the answers,

Have a good day,

Davide

Hi Davide,

This should work fine on an HP5 (or equivalent). An alternative solvent is toluene. You may well have to go to a high temperature to get it all off. Make sure that you run a reference sample of a new filter to compare.

Be prepared for a chromatogram that looks like a cross-section of the Alps!

Regards,

Ralph

As an alternative to instrumental analysis, try weighing the filter, extracting the oil, reweighing the filter, evaporating the solvent from the extract and weighing the residue.

Whether this works depends critically on how much oil there is on the filter of course.

Peter

Davide

Thank you for reminding me of the curious case of NIOSH 5026 where the relatively innocuous trifluorotrichloroethane (LVs in most countries = 1000 ppm in air) was substituted by carbon tetrachloride, a suspect human carcinogen (ACGIH TLV = 5 ppm, proposed European LV = 1 ppm).

Sorry NIOSH. The fume cupboard advice is good, but it fails the substitution test in the risk assessment.

As for the GC solvent I vote for cyclohexane.