Chromatography Forum

Hi All,
Trying to locate a good supplier for methylisothiazolinone. The issue with the product from Aldrich is its hygroscopic and even Aldrich admits that they are having trouble with the product (trying to deliver consistent % purity). I could try drying the product but it comes very wet. If you know of a supplier or any tricks to using this product to achieve consistent % purity please let me know. Has anyone ever used the methylisothiazolinone hydrochloride as a substitute? I am thinking of using it as my last resort and figuring out the pH changes that will result once the salt is in solution. Thanks for you help.

We've been through the same circle ourselves. For years we used reference standard from the methylisothiazolinone supplier, which was Dow, and about 10% MIT. Boss thought we should try Sigma ALdrich MIT but we had same issue with hygroscopic nature of it. Second time we ordered it, we found that it was really MIT hydrochloride.

We have tried the Sigma-Aldrich MIT-hydrochloride #M6045-1G 99% (which calculates as 75.87% MIT), but I feel more comfortable using the Dow reference material. So that's what I currently use, ask your supplier for a certified reference.

We've been doing MIT assays for three decades.

Hi Consumer Products Guy,
Really appreciate the input. Will go with the salt since the hygroscopic nature will not be easily solved. So just clarifying DOW reference standard is also the MIT-hydrochloride? If it is, was there a difference in DOW MIT-HCl purity when compared to to sigma's , thanks.
Any luck with IPBC (preservative) analysis using UV detection? Thanks again.

Hi Sahburn,

Here is a link that may help a bit with the UV spectrum of IPBC:

http://upcommons.upc.edu/e-prints/bitst ... _TCMTB.pdf

Please see what you think, and thank you.

So just clarifying DOW reference standard is also the MIT-hydrochloride? If it is, was there a difference in DOW MIT-HCl purity when compared to to sigma's , thanks.

Dow supplies the MIT standard as 10% in aqueous solution, with C of A.

Any luck with IPBC (preservative) analysis using UV detection?

Only in raw materials, where IPBC is typically used in combination with other active. For IPBC in finished product, we used HPLC-MSD back when we had that, could detect below 5 ppm IPBC. IPBC is tougher because it's not as good of UV chromophore and it's used at low levels.

Thanks much.