What is the status of Ceretropic's 7,8-DHF?

Every single one of the sources for 7,8-DHF on the market right now does not match Sigma Aldrich's reference standard for 7,8-DHF. Our supply from the lab we use matches THT's and TLR's perfectly. The issue is that none of them match Sigma's. We've purchased 7,8-DHF standards from Sigma twice now, just to make sure it was not an error on their end. Whatever is being sold by everyone right now does not seem to be 7,8-DHF, or has significant impurities that are throwing off our results.

Here is THT's compared to Sigma's standard. Sigma's is in red. You can see there are clearly differences in the functional groups present. THT's matches TLR's perfectly as well. So they are the same compound; probably the same lab.

Here is Sigma's vs another supplier. Sigma's in blue this time. This supply matches THT's and TLR's perfectly as well, just not Sigma's standard. I sent this one off to Colmeric Analyticals too. They did an HPLC and NMR. The NMR showed too many protons, but the HPLC had relatively matching retention times. However, the purity was only in the 92% range. So that means it is either 7,8-DHF with 8% impurities, or a very structurally similar compound with impurities. The extra protons in the NMR could be from the impurities alone, which would also account for the extra functional groups in our FTIR spectrum.

Now here is a different lab that we got a sample from. Sigma's in blue again. This one actually appears to be close to 7,8-DHF. However, there are extra peaks. They are either residual solvent (one which I have not identified yet), or some other impurity. We are trying to work with HPLC methods for it right now, to determine an exact purity. 7,8-DHF is a bitch to work with from an analytical perspective, though.

So samples that we tested from the current suppliers all did not match Sigma's standard. I am not sure exactly what is being sold as 7,8-DHF, but it does not match Sigma's reference material. It's clearly structurally similar to 7,8-DHF. It just seems to have extra hydroxyl groups, and some extra peaks in the fingerprint region. It could be a failed synth, or simply one with impurities left over. Our latest sample from a new lab seems to be 7,8-DHF. However, we are trying to get HPLC methods to work, and get an exact purity number, before we go ahead with a production batch. I have been working on this since April! There is no way I am selling something that I am not absolutely sure is correct and pure.

Essentially what is being sold on the market right now is either not 7,8-DHF, or has 8% impurities. Our new supply looks like it could be good. However, a final HPLC is being done to confirm. With how strange the results have been, I am being extra cautious to release ours.

I have a lab ready and waiting to synth 4'-dimethylamino-7,8-dihydroxyflavone for us. Cash flow is an issue right now, due to our card processing problems. So I am just waiting a bit.