Chromatography Forum

Does anyone know a method for 4-chloro-3,5-xylenol, or can point me in the right direction?

By GC: dissolve sample in DMF, add BSTFA to derivatize (shake), inject on non-polar capillary column like DB-1 or DB-5.

By HPLC: dissolve sample in DMF, methanol, etc., filter, run on RP-18 using either water-methanol or water-ACN that has 0.5% acetic acid in the water portion, wavelength at 280nm.

We've used these assays for years.

CPG's post was excellent.

An alternate GC analysis which may or may not separate isomers more effectively (too many years for me to remember clearly) dissolve in methanol and use a Carbowax or SP-1000 capillary column.

Try to use 0.5µm film or less if possible and 15 meters in length if available. Expect high, preferably isothermal temperatures.

I recall also with HPLC a similar mobile phase of methanol-water using 1% formic acid instead of acetic, but either should work I suppose.

good luck,

Rod

There are two methods reported the NIST Retention Index Database. Both come from the same article:

Colahan-Sederstrom, P.M.; Peterson, D.G., Inhibition of key aroma compound generated during ultrahigh-temperature processing of bovine milk via epicatechin addition, J. Agric. Food Chem., 53, 2005, 398-402.

The NIST RI Database has >250K GC methods for ~44K compounds.

About 25 years ago, we acquired a line of product which included a liquid soap with chloroxylenol (PCMX) at about 0.5%. Back then, we just explored and did the method devlopment/validation on our own. both thee techique worked fine, throughput wa more efficient with HPLC because we didn't have to temperature program then cool down the oven.

With HPLC, you'll use organic level less than 50%, as the chloroxylenol is pretty polar. I'd guess any acidic mobile phase would work fine, one is just making sure to keep the phenol group protonated.

Thanks a lot everyone!
We'll be using it for a raw material as well as a liquid soap eventually. The USP method uses nitrogen and a packed column, which we cannot do here, so thanks for all the suggestions everyone!

And, a word about USP methods. The USP is a great place to "start"; however, please don't take the USP as the "Bible" as the tests methods are submitted to them by other researchers who may have a different method than the one you've derived. I have found it necessary to implement alterations to most USP method in order to make the assays work for our finished products.

Oh trust me I understand. Our QA is not very flexible when it comes to USP even though USP is very outdated.

Oh trust me I understand. Our QA is not very flexible when it comes to USP even though USP is very outdated.

Is your QA going to set you up (that is: pay) for an outdated GC for packed-columns that would then need to be cGMP-qualified before doing the outdated USP assay?

The USP does not have any procedures for chloroxylenol in finished products, you'll be on your own to develop a procedure for your finished matrix and then cGMP-validate that.

I have found it necessary to implement alterations to most USP method in order to make the assays work for our finished products.

I assume your company then cGMP-validates those developed assays for your finished product matrices ????

Our QA states that even if such a standard procedure exists for a raw material (or has been used for a gazillion years, like titration of bleach with thiosulfate) that we must validate on our own product matrix.

CPG - Yes we do that.

And if I have to fully validate a USP method ANYWAYS, I see no reason to buy new columns and get the GC set up for Nitrogen. They will just have to wait a bit longer for a method development.

Now to use LC or GC...I like LC better.