J. Phys. Chem. B, Vol. 112, No. 18, 2008 5879
ADDITIONS AND CORRECTIONS
2007, Volume 111B Robert M. Mazo: Salting Out near the Critical Point In a previous paper,1 hereafter referred to as I, the present author gave a theoretical treatment of salting out based on the fluctuation theory of Kirkwood and Buff. More recently, Gutkowski et al.2 have presented a thermodynamic analysis of the same phenomenon. This paper will be referred to as II. Paper II comes to a different result than paper I and adduces experimental evidence in its favor. The authors therefore conclude that paper I is in error. They do not, however, attempt to locate the source of the error. The Editor of this journal gave me the opportunity to examine the manuscript of ref 2, and I was convinced, especially by the quoted experimental evidence, that I must indeed be in error. I have now located the position of the error and corrected it. There is an algebraic error in the transition from eqs 4-11 to eq 12, the final result of the paper; eq 11 is missing a factor of c01C00 12 in the first term on the right. This has been corrected both by redoing the calculation by hand and by doing it using algebraic software. The corrected eq 12 is
km ) -
c01M1 2 0 00 kTκ0(1 - c01C00 12)(1 - c1C1() 1000 2.303λ 1 (12)
00 00 00 C 1( ) (ν+C 1+ + ν-C 1)/ν
We have kept the notation of I and have retained only the divergent term of km. The corrected eq 12 no longer depends solely on the solventsolute interactions, nor is its sign determined solely by the partial molar volume of the solute (kTκ01(1 - c01C00 12) is the solute partial molar volume at infinite dilution). I believe that eq 12 is now consistent with the thermodynamic results of II and, furthermore, gives a molecular scale interpretation of the results. I would like to thank Dr. M. Laura Japas for pointing out a transcription error in an earlier version of this comment. References and Notes (1) Mazo, R. M. J. Phys. Chem. B 2007, 111, 7288. (2) Gutkowski, K. I.; Ferna´ndez-Prini, R.; Japas, M. L. J. Phys. Chem. B 2008, 112, 5671. 10.1021/jp801586z Published on Web 05/01/2008
