Questions arising in liquid phase detection
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For two batches of products from the same production run, one was analyzed using a Shimadzu detector with a C8 column; the retention time for the raw material was 2.6 minutes, while that for the product was 1.7 minutes. When the second batch was sent for analysis, since the equipment was busy processing other products and the workshop needed the results urgently, an Agilent detector with a C18 column was used instead. In this case, the retention time for the product was 3.5 minutes. Comparing this with the 1.9-minute retention time of the raw material, and not wanting to be certain of the accuracy, the retention time of the product was measured again, which came out to 3.6 minutes. Based on these results, the technical department determined the outcome of the reaction. But why does the order of peak emergence for the starting materials and the products reverse, even though the mobile phase is the same? Let’s analyze this and help me understand my confusion
It’s normal for the positions of the peaks to differ due to the different properties of the columns. I remember that Agilent’s columns are mostly manufactured by a supplier in Australia; it seems that Shimadzu also uses many columns from such suppliers. However, Shimadzu offers a wide range of brands, and it’s not clear whether they are assembled domestically. For C8 and C18 columns, you can look up their adsorption properties online to compare them and understand better
The peak emergence time is generally related to the chromatography column; the mobile phase and pH can also have an impact on it at times.
Friend on the second floor, where can I find information on the adsorption properties of columns? Is there any material on this topic? I can’t find it online. If you have it, please share it with me. Thank you!