Page 19 of 21 · 503 questions tagged hplc.
The case in front of me: oxidation · liraglutide · 40 °C. This is one of those things that everyone repeats and nobody derives. This matters practically, not just…
For reference: tirzepatide · a wide-pore C18 column · liraglutide. I am trying to choose between two options that are usually discussed as though only one exists. I…
Details up front: a TFA mobile phase · retatrutide · a C4 column. I suspect the usual explanation for this is wrong, or at least incomplete. I am aware this may have…
Concretely: PeptideMeter · 95.2%. I think I have a problem. I am not yet sure whether it is a real problem or a measurement artefact. I want to know whether this is…
Numbers first: hydrolysis · 2–8 °C. I can predict the outcome but I cannot explain it, which means I will get the next case wrong. I would like to know how confident…
Numbers first: 98.2% · list of related substances. I can parse the result. I am less sure what it licenses me to conclude. I have deliberately not looked at anyone…
What I have: 95.2% · list of related substances. I can parse the result. I am less sure what it licenses me to conclude. I have deliberately not looked at anyone…
Details up front: hydrolysis · 4 °C. I can predict the outcome but I cannot explain it, which means I will get the next case wrong. I would like to know how confident…
For reference: oral semaglutide · 95.2%. I would like the arithmetic checked rather than the conclusion asserted. I have deliberately not used an online calculator…
Numbers first: 97.6% · list of related substances. I can parse the result. I am less sure what it licenses me to conclude. I have deliberately not looked at anyone…
The particulars: an HPLC purity test · a five-person group buy. This is a planning question. I know what my options are; I do not know how to weigh them. What I want…
Details up front: 96.8% · retatrutide. This should be a straightforward calculation and I keep getting two different answers. The numbers are arbitrary; the method is…
The specifics, since they change the answer: liraglutide · a wide-pore C18 column · mazdutide. The comparison I want does not seem to exist anywhere in a form I can…
Concretely: aspartimide formation · liraglutide · minus 80 °C. I want to know whether this is a real physical effect or an artefact of how it is measured. What…
The particulars: deamidation · ecnoglutide · 4 °C. I would like the mechanism, because I want to be able to reason about the cases nobody has written about. I have…
Concretely: semaglutide · a C4 column · survodutide. These are treated as interchangeable and I do not think they are. If both are acceptable I would like to know…
For reference: VendorInvestigate · 96.4%. Something has gone wrong and I would like to know how badly before I decide what to do. Nothing else in the setup changed,…
The specifics, since they change the answer: 97.9% · list of related substances. I have the document in front of me and I can read the numbers. What I cannot do is…
The specifics, since they change the answer: aggregation · room temperature. I keep seeing this stated as a fact with no explanation attached, and unexplained facts…
I have the report as a PDF with the chromatogram on page two, so I can quote specifics. Something has gone wrong and I would like to know how badly before I decide…
Numbers first: 98.8% · orforglipron. I can do the algebra. I am not confident about the conversion factors. If there is a standard way to lay this out, I would rather…
For reference: fibrillation · ecnoglutide · 37 °C. I understand the observation; what I do not understand is the mechanism behind it. I have read the two review…
The case in front of me: survodutide · a C4 column · semaglutide. I would like the axes of comparison first and the recommendation second. I have tried the first…
Stated plainly: 99.4% · cagrilintide. The units are where I keep going wrong, so please be explicit about them. I have sanity-checked the order of magnitude and it…