By BRStudy on Monday, May 12, 2003 - 02:36 pm:
Dear Friends
I have difficult with Acetic Acid. Are there any degradation of this compound if I use 40 degree (1 min), 40 degree to 200 degree at 15 degree/min; FID detector (250 degree) and Injector at 200 degree?
Tanks
By Anonymous on Monday, May 12, 2003 - 08:22 pm:
No but there are a lot of other problems involved with measuring short chain free acids by GC, active sites(column, injector, and detector), elimination of ionized forms, side chemical reactions.
Good luck
By BRStudy on Tuesday, May 13, 2003 - 03:24 am:
Hi Anon-08:22;
Tank you for your help.
Maybe You invite-me any reference about your considerations?
Tanks,
By Anonymous on Tuesday, May 13, 2003 - 07:15 am:
No degradation ,I did 600 analysis of C2, C3, C4 short chain acids.RSD of 6.0% in a 4 meters FFAP (55 seconds each run). but you´ll have unreliable results due to bad peak shape in incorrect column
(namely: methylsilicone).
Be careful about the liner. if possible don´t use glass wool.
By BRStudy on Tuesday, May 13, 2003 - 08:56 am:
Hi Anon 07:15;
1 - Are there reaction between Acetic Acid and glass wool?
2 - When I inject Acetic Acid PA there are not evidence of degradation (one peak very high with retention time at 5.3min). But if I inject Acetic Acid at 30% in DMSO there are degradation of this analyte. What is it?
3 - Acetic Acid can degradate in the presence of DMSO over temperature between 40oC to 120oC?
4 - What column do You indicate for HeadSpace analysis of Acetic Acid?
Tanks.
By BRStudy on Tuesday, May 13, 2003 - 09:00 am:
Sorry Anon 07:15;
But
1 - What is the column FFAP that YOU analyse short chain acid in 55 seconds in each chromatographic run?
2 - Maybe You invite-me you analytical method for this analysis?
By BRStudy on Tuesday, May 13, 2003 - 09:38 am:
Hi Anon 07:15;
1 - Now I know one FFAP column, it is a "nitroterephthalic acid modified polyethylene glycol column designed for analysis of volatile fatty acids and phenols".
2 - Maybe I use one DB-624 column for analysis of Acetic Acid?
By Anonymous on Tuesday, May 13, 2003 - 01:07 pm:
DMSO? it boil at 180ºC, you can not use it as solvent with injector port at 200ºC.
acetic acid is not decomposing probably you are seeing a solvent peak.
The FFAP column was a comercial one from Supelco but I cut a 4 meter segment and used it, shorter columns give you shorter retention times.
don´t use glass wool in liner bacause of active sites, that was what the first anonymous said.
By BRStudy on Wednesday, May 14, 2003 - 06:57 am:
Dear Anon-01:07
Tank you for your help.
I will reduce the temperature of my injector to 140oC.
By Anonymous on Monday, May 19, 2003 - 05:13 am: