Chromatography Forum

Hi all,

I'm interested on an old subject related with analysis of NMP using European Pharmacopeia Method to comply ICH ....

I've seen this old part of conversation related with this compound. Using DMF, DMAc or DMSO I'm not able to see NMP... Our product is not soluble with water or aquous solvent..... I don't know where I can find ethylhexanol as solvent to try to use it.

Thanks

Basil

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By Anonymous on Friday, July 2, 2004 - 05:17 am:

yes, i know, that diluting works fine.

But, again, I cant find NMP. I tried H20, THF, and H20/PEG-1:1-mix as solvent. Maybe someone has an idea why NMP can't detected when it's diluted. Ethylhexanol works well.

Instrument:
GC6890, HSS7694

Inlet:
EPC-Split-Mode, 250°C, Pressure:12psi, Total flow: 63 ml/min, Split ratio 50:1, Gas saver:20ml/min

Column:
HP5-MS, He-flow: 1 ml/min, v=25cm/sec.

Oven:
60°C inital, 5°C/min till 16min, 8°C/min till 25 min, 15°C/min till end

HSS:
Vial temp: 100°C, loop: 110°C, tr.line:120°C
Vial equilibration time: 5min (2.5µl - 45min at 1ml), Pressurizing time: 0,2min, Loop fill time: 0,1min, loop equilibration=0,02min, injection time=0,1min

What chemical is abbreviated as NMP ?

NMP: N-methylpyrrolidone

This solvent has a low volatility and requires a very inert system to be detected by GC.

If present at low levels it would tend to be adsorbed by the rotor/steel transfer line of a headspace unit.

This is one analyte that should be tested by a PE headspace analyzer or by direct injection methodology. A fixed loop or sample valve system will perform this analysis with difficulty.

Expect temperatures higher than the boiling point of water in order to determine this solvent accurately on a very inert thick film capillary column.

If I can come up with direct parameters I will share them.