Chromatography Forum

Hey there. Just wondering if anyone else is doing any method work on this material. I'm trying to find a low cost column solution for a L1 packing 4.6 x 150mm column. I'm looking at a Symetry Shield from Waters but am looking for any other input that might run cheaper. Any help would be appreciated.

Hi,

I am not sure whether the USP monograph for Methylparaben is the same as in European Pharmacopoeia EP. Therein, also a C18 column is used (4.6 x 150 mm) using MeOH/Buffer 50:50 as mobile phase (buffer if I remember correctly: 6.8 g/L KH2PO4). In the EP knowledge database, it is outlined that a Phenomenex Prodigy is suitable or a GL Sciences Inertsil ODS-3. I tried Inertsil ODS-3 and it worked; and also Inertsil ODS-4 works.

Regards

Florian

Hi,

I am not sure whether the USP monograph for Methylparaben is the same as in European Pharmacopoeia EP. Therein, also a C18 column is used (4.6 x 150 mm) using MeOH/Buffer 50:50 as mobile phase (buffer if I remember correctly: 6.8 g/L KH2PO4). In the EP knowledge database, it is outlined that a Phenomenex Prodigy is suitable or a GL Sciences Inertsil ODS-3. I tried Inertsil ODS-3 and it worked; and also Inertsil ODS-4 works.

Regards

Florian

Thanks a bunch, I'll lokk into both of them!

Hello all.
LC chromatography and detect of methylparabene isn't problem. Its good solve in methanol (also in acetonitrile , alcohol , ect) small solve in water (1:80 (25C) -1:45 (90C)) , have hydroxybezene chromoforic group (ww1max=220nm E1%=200 ww2max=261 nm(pH1-8)E1%=30 or in Na salt (pH more 9)ww2max=290nm E1% about 70. pKa (phenyl) = about 3,5-4.
Simmetry, Dionex ( Nukleosil, Cromasil, Spherisorb others) - no particular difference, if L1 (C18) %C- more 5% and endcapping of silicagel.
Optimum organic phase 25-70% , optimum pH - smaller 3 or lager 5, optimum buffer molarity 0,05-0,5 M/L , optimum liquid phase speed - 1-1,5 ml (d=4,6 mm) or 0,1-0,15 (d=2mm), optimum T 20C to 40 C , need stabile temperature ( bad situation - after night in room 20 C air, sun peered through the window - in a room 30 C)

You problem -will be divided as the rest of the components of your sample. I know , that you sample - is a drugs (tablets, injections, liniments) or food. So they should check the completeness of extraction and the degree of separation the main components of the sample.