someone explain LC-MS to me like I have not read a paper in years
Posting this because I searched for it and got nothing useful.
Setup: 0.5mg, week 62, constipation present but not ruining anything. I changed exactly one variable — gradient — and tracked it for 15 weeks.
Result: a difference, but a small one, and well inside what I would call noise if someone else posted it. So I am putting it here rather than presenting it as a finding. If two or three other people have done the same thing we might actually learn something.
Not medical advice, obviously. This is one person with a spreadsheet.
best — the order this archive was captured in
This is the correct method framing. Column and gradient are load-bearing fields.
A shoulder on the main peak that 21 analysts integrated 12 different ways. Same trace, 97.4 spread.
The related substances profile is way more interesting than the main peak %. A 98% with 15 peaks is different from a 98% that is one 22% impurity.
related substances are where the story lives, not the main peak
related substances are where the story lives, not the main peak
Adding to this: integration is doing more work than the comment implies.
instrument quality is less important than analyst consistency
The related substances profile is way more interesting than the main peak %. A 98% with 13 peaks is different from a 98% that is one 39% impurity.
Disagree but this is the good kind of wrong — it is specific enough to be checked.
Yeah, the chromatogram profile matters more than the headline number.
state the method: column, gradient, detection wavelength, injection volume
Sceptical. If this were true we would see it reflected in the data and we do not.
state the method: column, gradient, detection wavelength, injection volume
instrument quality is less important than analyst consistency
Rodent data is rodent data. Dose scaling is not linear and the models tell you what to investigate, not what to expect.
integration decision on a shoulder changes your number by half a point on its own
two labs, two different baselines, two different purity numbers, both honest
two labs, two different baselines, two different purity numbers, both honest
Counter-anecdote: opposite result, same dose. Which mostly tells us the variance is huge.
I am going to push back on this slightly.
Yeah, the chromatogram profile matters more than the headline number.
Removed a chain here. The rule is one line long and it is not negotiable.
- 1instrument quality is less important than analyst consistency10 comments in this branch · started by u/phase_two_pete
- 2This is the correct method framing. Column and gradient are load-bearing…5 comments in this branch · started by u/hazard_ratio_hal