Help! I need some info regarding properties of quaternary ammonium chloride
compounds. I am specifically dealing with benzalkonium chloride
(BAK)(alkylbenzyl dimethyl ammonium chloride).
I have some questions regarding extraction of BAK from aqueous to organic
phases. BAK is soluble in water and polar solvents, so I presume it will be
soluble in chloroform.
In the problem that I'm working on, a blood sample suspected to contain BAK
was extracted (1:5) with chloroform/isopropanol. The organic phase was
retained, the chloroform was evaporated, the residue was treated with BSTFA
in TCMS and pyridine, and GC-MS was performed. BAK was not detected.
Questions:
Am I crazy? Since BAK is completely water soluble, chloroform/isopropanol
would not extract it. True?
Much of the literature I have read regarding purification of BAK or other
quaternary ammonium chlorides from biological matrixes states that they can
be extracted by ion-pair extraction techniques. The literature states that
the best ions for the protocol are Cl<Br<I. I am unfamiliar with this
technique, but I can envision a mechanism where the aliphatic portion of the
molecule forms a micelle with the inorganic ion in the middle. True?
Since Cl was the counter-ion used in the purification, and taking the water
solubility into account, the purification protocol used was not adequate and
it is not surprising that the GC-MS was negative. True?
Thanks in advance for your help!
Julie Dirks
jdirks at direct.ca or geoffnjulie at wwdb.org
