6 months in and gradient is still the thing I get wrong
I have had 15 orders now and I keep a table, so here is the honest summary rather than a vibe.
Material has been consistent. Communication has not. Shipping has varied by about 16 days on nominally the same lane, which matters more in summer than in February.
The independent number came back 98.4% against a claimed 98.6%, which I read as agreement rather than a discrepancy — inter-lab variance on this assay is a point or two either way and treating one lab as ground truth is how people end up in pointless arguments with vendors.
Batch number is in the comments. Ask if you want the method.
best — the order this archive was captured in
Tracking number removed. It identifies both ends of a shipment.
area% and mass% are not the same and this whole post conflates them
A shoulder on the main peak that 3 analysts integrated 13 different ways. Same trace, 98.6 spread.
state the method: column, gradient, detection wavelength, injection volume
state the method: column, gradient, detection wavelength, injection volume
Disagree on that part. 96.8% and 96.2% on the same vial is normal.
integration decision on a shoulder changes your number by half a point on its own
A shoulder on the main peak that 3 analysts integrated 13 different ways.
Adding to this: LC-MS is doing more work than the comment implies.
two labs, two different baselines, two different purity numbers, both honest
The related substances profile is way more interesting than the main peak %. A 98% with 21 peaks is different from a 98% that is one 33% impurity.
Small correction: the trial was 17 weeks, not 39. Does not change your point but people will quote it.
The confident tone is doing a lot of work that the evidence is not.
The related substances profile is way more interesting than the main peak %. A 98% with 2 peaks is different from a 98% that is one 23% impurity.
Tracking number removed.
Yes, exactly this, and it is the bit that took me 96 weeks to accept.
Disagree. What you are describing is consistent with LC-MS, not with what you concluded.
Not convinced. The evidence does not support that reading.
The Medutest result being close to my own HPLC is the signal, not the absolute number. Both are right.
a round-robin on baseline integration would be genuinely useful
a round-robin on baseline integration would be genuinely useful
Disagree on that part. 99.0% and 98.9% on the same vial is normal.
the detector wavelength matters more than people think
a round-robin on baseline integration would be genuinely useful
Adding to this: chromatogram is doing more work than the comment implies.
Crossposting this to c/glp1uk because the people who need it are not reading this community.
Injection volume and flow rate? Those affect resolution.
Gradient goblin mode: changed the solvent composition 5 times, finally got good resolution on a gradient peak.
related substances are where the story lives, not the main peak
Not convinced. The evidence does not support that reading.
area% and mass% are not the same and this whole post conflates them
- 1Tracking number removed. It identifies both ends of a shipment.15 comments in this branch · started by u/peak_area_pete
- 2Not convinced. The evidence does not support that reading.7 comments in this branch · started by u/niels_lindqvist