Microbiology List: FW: Benzalkonium Chloride

Robert Friedel Rfriedel at perrittlab.com
Mon Mar 19 10:37:44 EST 2001

Deluca, P.P. and H.B. Kostenbauder (1960) "Interaction of Preservative with
Macromolecules IV.  Binding of Quaternary Ammonium Compounds by Nonionic
Agents", J. Amer. Pharm. Assoc., Vol. 49, No. 7, pp. 430-437.

Kazmi, S.J.A. and A.G. Mitchell (1976) "The Interaction of Preservative and
Nonionic Surfactant Mixtures", Canadian J. Pharm. Sci., Vol. 11, No. 1, pp.

Kurup, T.R.R., Wan, L.S.C. and L.W. Chan (1991) "Effect of Surfactants on
the Antibacterial Activity of Preservatives", Pharm. Acta Helv., Vol. 66,
No. 9-10, pp. 274-280.

A couple of references for you. 

Surfactants will modify the cell surface permeability.  The key to synergism
between non-ionic surfactants and preservatives is to formulate the
preservative system so the concentration of the surfactant is below the
critical micelle concentration (CMC).  If the system is above the CMC, the
preservative will be trapped within the micelle.  Another important factor
when using BAK is the pH.  The effective pH is slightly alkalkine.

Bob Friedel
Quality Assurance Manager
Perritt Laboratories, Inc. 
rfriedel at perrittlab.com  

-----Original Message-----
From: Hochberg, Alan M [mailto:Hochbeam at Qualicon.email.dupont.com]
Sent: Monday, March 19, 2001 9:48 AM
To: micro-list at qualicon.com
Subject: Microbiology List: FW: Benzalkonium Chloride

From: johnmackenzie at genie.co.uk [mailto:johnmackenzie at genie.co.uk] 
Sent: Saturday, March 17, 2001 5:46 AM
To: microbio at hgmp.mrc.ac.uk
Subject: Benzalkonium Chloride

I am doing an A level project on disinfectants and their effectiveness on
Bacillus subtilis.  Please can you tell me the method by which BAC combined
with a non-ionic surfactant kills such a bacteria?  Thank you


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