Cetrimide

Cetyl trimethyl ammonium bromide (CTAB) , aka hexadecyltrimethylammonium bromide, or 1-Hexadecanaminium, N,N,N-trimethyl-, bromide (C₁₆H₃₃N(CH₃)₃Br) is one of the components of the antiseptic cetrimide. It is a cationic surfactant. Its uses include providing a buffer solution for the extraction of DNA. more...

As any surfactant, it forms micelles in aquous solutions. At 303 K (30 °C) it forms micelles with agregattion number 75-120 (depends on method of determination, usually avrg. ~95) and degree of ionization α (fractional charge) 0.2 - 0.1 (from low to high concentration).

Standard constant of Br- counterion binding to the micelle at 303 K (30 °C), calculated from Br- and CTA+ ion selective electrode measurements and conductometry data by using literature data for micelle size (r= ~3 nm), extrapolated to the critical micelle concentration is K°≈400 (it varies with total surfactant concentration so it is extrapolated to the point at wich the concentration of micelles is zero).

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