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Falling down baseline problem !!!!
Posted: Wed Oct 17, 2012 7:28 pm
by ChromaMaster
recently i used a mobile phase (70% KH2PO4 Buffer + 30% Acetonitrile , pH 6.5 ) and Column C18(4.6*250),5micron , UV detection @ 210nm . the system was keeping fall in baseline and took 4 hours to get stable baseline , what is the problem ???????????
Re: Falling down baseline problem !!!!
Posted: Wed Oct 17, 2012 11:46 pm
by danko
The column has been polluted. Or brand new.
Maybe you should've pumped/mixed some more ACN in the flow (60 - 70 %) for a while.
Beware of high phosphate concentration (> 0.05 M) if you follow my advice.
Best Regards
Re: Falling down baseline problem !!!!
Posted: Fri Oct 19, 2012 9:45 pm
by ChromaMaster
The column has been polluted. Or brand new.
Maybe you should've pumped/mixed some more ACN in the flow (60 - 70 %) for a while.
Beware of high phosphate concentration (> 0.05 M) if you follow my advice.
Best Regards
i used a new Waters symmetry column, should i do any treatment with a new column before use ???
Re: Falling down baseline problem !!!!
Posted: Fri Oct 19, 2012 10:58 pm
by danko
My suggestion is:
1. pump some 20 - 30 mL 20/80% water/ACN
2. pump some 20 - 30 mL of you mobile phase
3. Again 20 - 30 mL 20/80% water/ACN
4. Equilibrate with your mobile phase (20 - 30 mL)
5. Ready to run your samples.
Best Regards