#hplc-massspec 2025-10-14

Tuesday14 messages3 participantstimes are UTC

Highlights from this day

ghent_gradient — does ms/ms actually prove identity or just make it very likely 19:39
ghent_gradient — the honest position is that hobby-level interpretation of a chromatogram is worth something but not much, we shall see 19:41
ghent_gradient — tirzepatide is about 4813.5 Da, so 2+ is near 2407.8 and 3+ near 1605.5 19:44
mg_per_ml — two labs a point or two apart on the same lot is normal and gets mistaken for one of them being wrong constantly 19:54
mg_per_ml — genuine question i asked Medutest for the raw trace and they sent it. that is the right answer to that question 20:35

plus 0.98 is deamidation

oxidation is about plus 15.99 Da and is usually methionine or tryptophan, ask me again in a month

does ms/ms actually prove identity or just make it very likely

✅5💀4🔥8

the honest position is that hobby-level interpretation of a chromatogram is worth something but not much, we shall see

tirzepatide is about 4813.5 Da, so 2+ is near 2407.8 and 3+ near 1605.5

🧪5🎉2🤝18

thats the solvent peak

why do two labs integrate the same peak differently

can you tell a dimer from the chromatogram alone

two labs a point or two apart on the same lot is normal and gets mistaken for one of them being wrong constantly

whats the void volume peak, is that always solvent

retention time is a hint

📈10😂6🤝16

my peak has a shoulder on it, what does that usually mean

i was wrong about tailing factor. it is usually the injection or the pH, not the column, we shall see

genuine question i asked Medutest for the raw trace and they sent it. that is the right answer to that question