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- Posts: 46
- Joined: Mon Feb 11, 2013 10:13 pm
Agilent 1290(new), M.Phase: 0.5%formic acid in H2O,PH8.5 by NH3/MeCN
DAD:230,4 ref:300,100
By the way, why when we use needle wash the vial must be uncapped?
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Discussions about HPLC, CE, TLC, SFC, and other "liquid phase" separation techniques.
Sorry to be a stickler, but *which* Prontosil C18, specifically? Which Phenomenex column? Do you know the pH limits of each?i use prontosil c18 250x4.6 ,5μm but i tried one from phenomenex as well with the same results.I "play" with the temperature a bit but it's from 20 to 35C.
it must be the mobile phase. When i wash H2O/ACN: 50/50 the noise is fine. when i put M.phase A in water's channel and begin to equilibrate the noise is about 1mAU (only at 230nm). Formic acid maybe?
i changed channels several times. i don't believe PH 8.5 (+ %ACN) will be much trouble for these columns. the 1 of 2 prontosil i used was brand new.it is long -term noise and it's only for 230nm. In this analysis i have dual wavelength 230/320 and in 320 the noise is fine. This is a brand new LC, i wouldn't blame the lamp. The pressure is pretty steady.I don't blame the glassware either. i have done the same analysis 3 times in 30 days and i had the same problem.
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