purity

method development — 13 things I got wrong before I got it right. Not a hot take, just something I have not seen said plainly here. Ran a blank after a…

The title is the whole question — why does nobody talk about purity — but here is why I am asking. If the report gives a mass spectrum as well as UV purity, say so.…

the purity advice in here is 2 years out of date. Making the case below, and I expect to lose some of it in the comments. Pulling the figures out of the title: 2 years.…

proposal — a flair for LC-MS posts. Short post, long comment section, probably. QYB sent me the column, the gradient and the theoretical mass without being asked. That…

SGN vs ERP on the same compound, same month — both cleared 97.0%. I will put the method line and the batch identifier up front because that is what makes this…

split one vial across VendorInvestigate and PeptideMeter — 97.2% and 96.8%. One vial, one service, one member paying, which is the only kind of result this board should…

CPC cagri — Janoshik came back 98.1% against a claimed 97.5%. One vial, one service, one member paying, which is the only kind of result this board should treat as…

batch is the most under-discussed thing on this board — a position I have arrived at slowly and would like tested. Tested three lots over a year rather than three vials…

Something I keep coming back to: unpopular opinion: most of what gets said here about area percent is guesswork. Spent four months confusing area% and mass% in every…

help me understand area percent, I have read the wiki twice. If this has been answered properly somewhere, link me and I will delete. How to ask for a batch record…

area percent — 13 things I got wrong before I got it right — a position I have arrived at slowly and would like tested. LC-MS gives you identity; UV purity gives you a…

genuine question about LC-MS that I am slightly embarrassed to ask. Searched first, found three threads that contradict each other, hence the post. Resolution between…

we are measuring certificate of analysis at the wrong time and calling it noise. Change my mind, genuinely — I have no stake in being right about this. Water content…

Asking properly rather than in a comment on somebody else’s thread: how do you actually verify method development. The system suitability argument, since it comes up…

can we stop arguing about HPLC until somebody posts a number. I am not trying to be the "source?" guy. I would just like a source. System suitability — repeat…

The one-line version is the title: why amino acid analysis catches the frauds HPLC misses. The rest is why. Carryover from a previous high-concentration injection looks…

7th independent test on WXT — 99.2% on a claimed 98.5%, and the trend is the interesting part. That is the headline. The document, the batch and the service are below…

Asking properly rather than in a comment on somebody else’s thread: how do you actually verify Janoshik. On inter-lab disagreement, which generates more heat here than…

Genuine question, and the title is the question: can we stop arguing about COA until somebody posts a number. Spent four months confusing area% and mass% in every post…

Numbers in the title, numbers in the post. 16th independent test on ERP — 97.4% on a claimed 97.0%, and the trend is the interesting part. Since the title puts numbers…

Slightly embarrassed to be asking this, but: purity — what am I missing here. My first certificate had a compound name, a percentage and a logo. I thought that was…

reading below spec threads from 2024 and half of it aged badly. Not a hot take, just something I have not seen said plainly here. CPC BPC, batch matched the paperwork,…

the batch advice in here is 3 years out of date. It is the sort of thing everyone half-believes and nobody writes down. The relevant figures are 3 years, and they come…

unpopular opinion: most of what gets said here about water content is guesswork, and I am aware this is a minority view on this board. UV at 214nm sees the peptide bond…

area percent — what am I missing here. Searched first, found three threads that contradict each other, hence the post. Asked QSC for the batch-specific certificate and…