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- Posts: 30
- Joined: Wed May 30, 2018 5:28 pm
I'm developing a method to analyse sorbitol in grape juices.
I tried water as mobile phase. The baseline is good, the standards are good. But I had some coelunt with sorbitol.
So, I tried change the mobile phase. I tried use 10% of acetonitrile and 90% of water. The separation is better. But the baseline drifts up and down. The noise is so big and the analyte peak is so small that the results aren't accurate.
I use a refractive index deterctor (RI).
The baseline drifts just when I use acetonitrile:water (10:90) as mobile phase.
I mixed the water and the acetonitrile before use it. I'm using just one channel pump for the mobile phase.
The acetonitrile barnd is Merck, gradient grade for liquid chromatography.
The column is an Aminex HPX 87C, from Bio Rad.
Flow: 0,6 mL/min.
Oven temperature: 80°C.
What can I do?
Thank you!