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sodium pyrosulfite's problem

Posted: Wed Oct 08, 2008 7:55 am
by Austin
Our workmates countered a problem: RP-LC is used to separate impurities in an in-process product, and the sample was dissolved in 0.1% sodium pyrosulfite aqueous solution, and HPLC parameters as following:

column: Agilent C18 column;
detection: 210nm, 300nm
temperature:25oC;
inject volume: 10ul;
mobile phase: A: 10mM phosphate buffer(pH2.2) , B: methanol

Gradient program: phase A: 97% to 50%;
phase B: 3% to 50%;

After loading sample, an abnormal chromatogram shows a shoulder peak adhesive to the interest peak(RT 3.2min), and the percetage rises gradually, but the ghost peak exists no longer when sample dissolved in pure water, so we think that sodium pyrosulfite leads some reactions. Please give us some advices. Thanks!

Best regards

Austin[/code]

Posted: Sun Oct 19, 2008 3:49 am
by XL
Austin,

What happened if you only injected pyrosulfite solution? I was wondering if the large amount of pyrosulfite interfered with the main peak whose retention seems pretty low. Did this ghost peak show up at both 210 nm and 300 nm wavelengths?