I usually run an analysis on Thermo Ultimate 3000 HPLC, using the sample temperature of 15 °C. The retention time of the peaks due to epinephrine and dopamine are, respectively, 3 min and 6 min. Today, I ran the same analysis, in the same equipment, using the sample temperature of 10 °C. The retention times have changed to 1.5 min and 3 min. No other paramether was changed. Does anyone have an ideia of what might happened? Thank you.
Hello, the difference of 5*C in sample temperature cant made so big changes. May be you change the column temperature which can made the effect that you mentioned.
Can you provide more info regarding mobile phase and for more reliable answer. May be something changed in mobile phase gradient etc.
What is the operational system you are using? I mean especially the column type and mobile phase composition.
Usually when increasing the temperature retention times decrease, read for example http://tools.thermofisher.com/content/sfs/brochures/WP-71499-LC-Temperature-Column-Thermostatting-WP71499-EN.pdf
Hello, the difference of 5*C in sample temperature cant made so big changes. May be you change the column temperature which can made the effect that you mentioned.
Can you provide more info regarding mobile phase and for more reliable answer. May be something changed in mobile phase gradient etc.
I did not change the column temperature. That's why I am thinking this is weird.
The column is: Thermo Hypersil Gold C8 (150 x 4.6 mm, 5 µm)
The mobile phase composition is: 0.05 M phosphate buffer pH 3.8 (with 0.05 mg/mL sodium octanesulfonate and 0.05 EDTA) and methanol (85:15)
So you are running ion-pair on a C8 column. The sample temperature could only be relevant if you inject a large amount. If your system is sensitive for e.g. small changes in pH or octanesulphonate then another lot of mobile phase could create a significant difference.
Or a shock causing a rupture in the column packing.
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