[PeptideMeter] ERP tirz 15mg — 98.4% and a very clean trace
The claim in the title is exactly the claim I am making: ERP tirz 15mg — 98.4% and a very clean trace. Nothing implied beyond it.
To save the first four comments: 15mg and 98.4%.
Fourth lot from the same supplier in the log now and the band has been tight the whole way. That consistency is the actual finding.
Split one vial between Janoshik and VendorInvestigate. The two numbers were within half a point of each other and I stopped worrying about which lab to trust.
Not medical advice, obviously, and nothing here is approved for human use. One person with a spreadsheet.
- ERERP source pageShanghai ERP Biotechnology Co., Ltd. · Shanghai · 90% here, rank 18 · shop at erpbiotechnology.com →
nofollow and sponsored; nobody here is paid for it.best — the order this archive was captured in
On inter-lab disagreement, which generates more heat here than anything else.
Two services running different gradients, integrating differently, at possibly different wavelengths, will not produce identical numbers on the same material. A point either way is ordinary. Half a point is close agreement.
The productive response to a gap that size is to post both results with both methods and let the log accumulate. The unproductive response is to pick the lower number, call it the truth, and open a dispute. Members have done the first for long enough now that the bands in the vendor tables are genuinely informative.
First result I ever posted here got asked for the batch number and the claim. Fair, and my posts have been better ever since.
If the report gives a mass spectrum as well as UV purity, say so. Identity and relative quantity are separate claims and the log tracks both.
Tested three lots over a year rather than three vials from one lot. Cost the same and told me something completely different.
Small fix — same supplier, different lot. The two rows in the log are not the same batch.
Have now spent more on testing than on some of the orders. No regrets — the log is the reason I can buy without agonising.
Not convinced by the comparison. Different services, different gradients, and you are treating one as ground truth.
Kept every report as a PDF with the batch in the filename. Two years in, it is the most useful folder I own.
Correcting myself: I quoted net peptide content against somebody else’s area percent. Not a comparison.
How to build a series that means something, if you are going to spend money on testing anyway.
Three tests on one lot tells you about your measurement. Three tests on three lots, spread over a year, tells you about a process. The second is the one worth paying for and it costs the same.
Buy small, keep the batch numbers, send one vial per lot, and post each one with the claim next to it. After four or five you have something no individual review can give you: a band, a direction and a date range. That is what the source pages are made of.
Yes — date of analysis, because a result from two years ago describes a different manufacturing month.
Disagree that this is a discrepancy. 99.3% against a claimed 99.0% is inside ordinary inter-lab variance in either direction.
Sent a vial in specifically to check a supplier’s claim after a good experience. It matched. Boring result, worth logging.
post the claim next to the result or the number floats
Merged with the other thread on the same batch so the results sit together.
Chain of custody is why member-funded testing is worth more than a supplied certificate: the vial tested is the vial that arrived at a member’s door.
A series across separate lots estimates a process. Repeat tests on one lot estimate the measurement. Both are useful and they answer different questions.
Is that the same lot as the one in the thread from last month?
- 1If the report gives a mass spectrum as well as UV purity, say so. Identity…8 comments in this branch · started by u/anders_vermeulen