I specifically have a Nonylphenol ethoxylate-50 that is phosphated with polyphosphoric acid. The percentages of these components is such that there is a significant amount of free nonionics (NP-50) which remains unreacted. I would like to know if there is a GC procedure for determining the level of free NP-50. If there is, what is it or where can I find it.
By Anonymous on Wednesday, April 16, 2003 - 11:38 am:
NP-50 is large, and a mixture of various EO chains and varying positions where the aromatic attaches to the alkyl portion. We suggest HPLC using UV detector. You could also do straight UV if you remove the ionic portion first using an SPE ion-exchange extraction column. You could also do gravimetrically by passing through mixed-bed ion-exchange and blowing off the solvent.
By Ralph Calvert on Tuesday, April 22, 2003 - 04:25 am:
In addition (but less elegant than the above suggestion) - after ion exchange to hold back the phosphated species the eluted unreacted nonionic ethoxylate can be treated with HBr in glacial acetic acid. This cleaves off the ethoxylate as dibromoethane and leaves you with the alkyl phenol as its bromide. This is volatile and can be quantified by GC.