Certificates issued by the seller versus by a laboratory posts 31–60
This is a continuation of a long topic, addressed by post number rather than by page. Start at post 1.
Building on post #30 rather than restating it.
A chromatogram supplied as a small image is legible for peak shape and not for baseline detail. That is enough to sanity-check an integration and not enough to reproduce it.
I have written this out at length because the short version keeps being misread.
Where I part company with post #32, and it is a narrow parting.
An itemised related-substances table with retention times says considerably more about the synthesis than a single total. A total tells you how much is not the main peak and nothing about what it is.
Collapsed as off-topic by two members at trust level 3 or above
The distinction between release testing and characterisation is one industrial documents make and retail ones usually do not. It is the difference between "we tested every lot for this" and "we established this once".
A chromatogram supplied as a small image is legible for peak shape and not for baseline detail. That is enough to sanity-check an integration and not enough to reproduce it.
An itemised related-substances table with retention times says considerably more about the synthesis than a single total. A total tells you how much is not the main peak and nothing about what it is.
The right answer here may simply be that it has not been measured.
The distinction between release testing and characterisation is one industrial documents make and retail ones usually do not. It is the difference between "we tested every lot for this" and "we established this once".
Reading old certificates: if a certificate is dated years ago, the lot it describes might be old. That is not automatically a problem but it is worth noting. Fresh testing on the current lot is stronger than old testing on an older lot.
I have seen it go both ways, which is why I hedge.
A chromatogram supplied as a small image is legible for peak shape and not for baseline detail. That is enough to sanity-check an integration and not enough to reproduce it.
It is a small point and it changes the answer, which is an awkward combination.
The distinction between release testing and characterisation is one industrial documents make and retail ones usually do not. It is the difference between "we tested every lot for this" and "we established this once".
Somebody will have a better source than mine, and I hope they post it.
Post #40 is the version of this I will quote in future. One addition.
An itemised related-substances table with retention times says considerably more about the synthesis than a single total. A total tells you how much is not the main peak and nothing about what it is.
Where I part company with post #42, and it is a narrow parting.
The distinction between release testing and characterisation is one industrial documents make and retail ones usually do not. It is the difference between "we tested every lot for this" and "we established this once".
Not disagreeing with anyone above, just adding the bit I keep having to look up.
A chromatogram supplied as a small image is legible for peak shape and not for baseline detail. That is enough to sanity-check an integration and not enough to reproduce it.
Adding a source would improve this post and I do not have one to hand.
Certificates from a supplier's own laboratory are not independent by definition. That is not an accusation, it is a description, and it is why independent submission exists.
Adding a data point of agreement rather than a data point.
An itemised related-substances table with retention times says considerably more about the synthesis than a single total. A total tells you how much is not the main peak and nothing about what it is.
That is a description of practice, not a recommendation of it.
Collapsed as off-topic by two members at trust level 3 or above
A chromatogram supplied as a small image is legible for peak shape and not for baseline detail. That is enough to sanity-check an integration and not enough to reproduce it.
That reframing is the whole thing. The facts I already had.
The distinction between release testing and characterisation is one industrial documents make and retail ones usually do not. It is the difference between "we tested every lot for this" and "we established this once".
The literature is thinner on this than the confidence in the thread implies.
An itemised related-substances table with retention times says considerably more about the synthesis than a single total. A total tells you how much is not the main peak and nothing about what it is.
If this contradicts something upthread, the upthread version may well be the better one.
Post #53 is right about the mechanism and I think understates the practical bit.
Reading old certificates: if a certificate is dated years ago, the lot it describes might be old. That is not automatically a problem but it is worth noting. Fresh testing on the current lot is stronger than old testing on an older lot.
I had written a reply contradicting post #53 and deleted it. Here is what survived.
The distinction between release testing and characterisation is one industrial documents make and retail ones usually do not. It is the difference between "we tested every lot for this" and "we established this once".
Confirming post #57 from a second method, which matters more than confirming it from a second person.
An itemised related-substances table with retention times says considerably more about the synthesis than a single total. A total tells you how much is not the main peak and nothing about what it is.
A chromatogram supplied as a small image is legible for peak shape and not for baseline detail. That is enough to sanity-check an integration and not enough to reproduce it.
I am confident about the direction and much less about the magnitude.