Chromatography Forum

Hi, I want to know what are packing materials for hplc grade solvents? solids?. will plastic inner spoil hplc grade?
Best regards,
gprane

Solvents should be in glass bottles. Solids are less of a problem (less likely to leach impurities from plastic bottles).

Tom, I guessed the original question referred to plastic inserts in the tops of glass HPLC solvent bottles. I would imagine that a reputable manufacturer would have investigated this and that there would be complaints from users if such liners were leaching impurities.

It has always intrigued me that users always accept Teflon lined stoppers, or teflon faced septa as being the ultimate in chromatography. However, while Teflon is chemically inert, it does not mean that solvents could not leach impurities or plasticizers from this material...any comments anyone?

I have not checked recently, but at least one of my suppliers used white PP insert disks on the top of most solvent winchesters, rather than PTFE. Easy test - submerge in a beaker of water and see if it sinks or floats, confirm PP by touching it to a hotplate - paraffin smell.

I assume HPLC solvent manufacturers specify appropriate grades of cap insert material. but it's interesting to note that Schott now offer a new polymer cap with PTFE facing on both sides of the insert for their Duran borosilicate bottles, so maybe there have been some issues.

The problem for PTFE inserts and sheet, well known in the GC community, is that PTFE sheet is very difficult to roll during manufacture, so a thin oil is usually used to lubricate the roller surfaces.

Some grades of PTFE ( eg "for oxygen service" ) are manufactured without lubricant, but even PTFE threadseal tape may have lubricant on the surfaces.

For GC or TOC work ( looking for trace HCs ) I tend to wash PTFE ( and any other polymeric ) inserts by ultrasonication with two lots of warm 60:40 chloroform: methanol, but I've seen one analyst use a soxhlet extractor and dichloromethane - because of previous contamination issues.

I'm always wary of using sintered materials ( including filters ), whether metal or polymer, without precleaning - for the same reasons.

It's really difficult to clean polymers ( eg PP ) that absorb solvents and swell, and many disposable " laboratory grade " polymers have various trace additives that can produce contamination for a long time.

They are fine for most aqueous work ( except perhaps for MS detectors), but solvents, esepcially alcohols and ketones may extract junk.

If concerned about organic contamination, use properly cleaned glassware.

Bruce Hamilton