I am currently working on developing a method for the analysis of methyl and propyl paraben in a shampoo. I am having trouble finding a column that provides good resolution (greater than 1.5) for all of the peaks. Any input??

We used to use a Waters Microbondapak column for this and had not problems. Any good c18 should work. You probably just need to look at the mobile phase composition.

Hallo Sue,
you find an application at www.macherey-nagel.com. Look at application ; application nr. 100680 ( PHBA: separation of food preservatives by HPLC ).
Peter

Sue,
I used Waters Symmetry C18 column 3.9x150mm 5um with methanol and water gredient mobile phase. The methyl and propyl paraben peaks were 6 and 10 minutes. I have never done shampoo but you can try the method.

Hi,

I have another more specific question to add to the topic. One of the biggest problems that I am experiencing is a very dirty sample. I am currently looking into some sample clean up techniques. Any suggestions there? Also I am using a mobile phase of a mixture of water and methanol, is this common MP for Parabens?

Sue,

A MP of 65/35 works great. Gives good resolution and peak shape. You can also change it to 70/30 and still get resol. greater than 2. A 3.9 X 150mm NovaPak C18 works great and are very rugged columns.

Parabens are among the most commonly separated compounds and are easily done on a variety of reversed phase colunms. Look in the applications section of various HPLC supplier catalogs and you should find a wealth of information. If you need to clean up yor sample, I would suggest reversed phase solid phase extraction (SPE). You'll need to do some experimentation here, depending on the nature of your contaminants, and you'll need to show reproducible recovery.

I have quantified these components in a variety of matrices for years, so if you need any specific help, drop an e-mail and I'll do what I can.

Chris