Commenting on the Letter entitled 'Destructive and protective action of sodium dodecyl sulphate micelles on the native conformation of Bovine Serum Albumin: A study by extrinsic fluorescence probe 1-hydroxy-2-naphthaldehyde' [Chem. Phys. Lett. 463 (2008) 183], this short contribution aims to clarify that the critical micellar concentration (CMC) of a charged surfactant strongly depends on the ionic strength. Main features of fluorimetric determinations of the CMC are also briefly discussed. In general, the study of surfactant-induced protein transitions will greatly benefit from independent 'blank' experiments to evaluate the CMC of the surfactant under the conditions of the protein assays. (C) 2009 Elsevier B. V. All rights reserved.