purity

Posting this as a discussion rather than a claim: unpopular opinion: most of what gets said here about HPLC is guesswork. Retention time shifted 0.4 minutes and I…

Question in the title, detail here: do test results actually matter or is it forum lore at this point. Have now spent more on testing than on some of the orders. No…

Slightly embarrassed to be asking this, but: Janoshik — what am I missing here. A series across separate lots estimates a process. Repeat tests on one lot estimate the…

The title is the whole question — someone explain COA to me like I have not read a paper in years — but here is why I am asking. The PDF creation date being later than…

Posting this because the title is the whole finding — KP vs BCH on the same compound, same month — both cleared 97.5% — and a number without its method is a rumour.…

chromatogram is the most under-discussed thing on this board. I have gone back and forth on this for months. System suitability — repeat injections, tailing factor,…

The title is the whole question — how much of what we believe about area percent actually comes from COA threads — but here is why I am asking. Started keeping a folder…

does purity actually matter or is it forum lore at this point. Searched first, found three threads that contradict each other, hence the post. Asked QST for the…

Short version of the title, which is already short: split one vial across VendorInvestigate and PeptideMeter — 98.6% and 98.4%. Longer version underneath. Figures up…

The claim in the title is exactly the claim I am making: split one vial across VendorInvestigate and PeptideMeter — 99.1% and 96.8%. Nothing implied beyond it. Numbers,…

proposal — a flair for water content posts. Nothing about this affects the ranking maths, before anyone asks. Ask what the stability statement was written against —…

The title is the argument: purity is doing more work than we give it credit for. Here is the rest of it. The PDF creation date being later than the analysis date is…

how much of what we believe about purity actually comes from PeptideMeter threads — that is what I am asking, and I have already read the wiki twice. First result I…

how much of what we believe about HPLC actually comes from LC-MS threads. Searched first, found three threads that contradict each other, hence the post. Chased a ghost…

purity is not what most of this community thinks it is. Two minutes of reading now saves an argument later. My first certificate had a compound name, a percentage and a…

The title is the argument: unpopular opinion: most of what gets said here about COA is guesswork. Here is the rest of it. The PDF creation date being later than the…

Genuine question, and the title is the question: how much of what we believe about HPLC actually comes from integration threads. Started reporting my own integrations…

the below spec advice in here is 2 years out of date. I have gone back and forth on this for months. The numbers the title promised, since a headline without them is…

Something I keep coming back to: area percent is doing more work than we give it credit for. Spent four months confusing area% and mass% in every post I made here. One…

Janoshik is not what most of this community thinks it is. If you already knew this, the post is not for you and you can scroll on. FGP BPC, batch matched the paperwork,…

The title is the argument: we are measuring LC-MS at the wrong time and calling it noise. Here is the rest of it. SWB sent me the column, the gradient and the…

is 96.8% actually fine or am I being sold a rounding error, and before anyone asks: same batch throughout, single submission, no cherry-picking between services. 96.8%…

three years of Janoshik threads, summarised so you do not have to read them — a position I have arrived at slowly and would like tested. Tested three lots over a year…

Thinking out loud about this: test results — 20 things I got wrong before I got it right. First result I ever posted here got asked for the batch number and the claim.…

how do you actually verify purity — that is what I am asking, and I have already read the wiki twice. Mass spectrometry answers identity. UV purity answers relative…