The variation of the critical micelle concentration of sodium dodecyl sulphate with ionic strength monitored by selective-ion membrane electrodes

1979 ◽  
Vol 257 (7) ◽  
pp. 773-775 ◽  
Author(s):  
J. E. Newbery
1991 ◽  
Vol 56 (4) ◽  
pp. 785-795 ◽  
Author(s):  
Jiří Bílý ◽  
Ludmila Čermáková ◽  
Jiří Knapp

The values of the apparent dissociation constants of the azo dye 4-(2-pyridylazo)-resorcinol (PAR) have been found in the presence of sub- and supercritical concentrations of the anionogenic tenside sodium dodecyl sulphate (SDS) and the effects of the strong electrolytes NaCl and NaNO3 were also evaluated. In both electrolytes, the pKan values initially are independent of the SDS concentration and then increase. Spectrophotometric and surface tension measurements were employed to determine the critical micelle concentration (cmc) of SDS alone and in the presence of PAR and the given electrolytes. The determined cmc values were in the range 0.20–3.02 mmol l-1 and dependent on the type and concentration of the particular additive.


2011 ◽  
Vol 4 (1) ◽  
pp. 135
Author(s):  
M. A. Hossain ◽  
M. A. Rahman ◽  
M. A. Subhan

The specific conductance of aqueous solutions of sodium dodecyl sulphate (SDS) was measured from 20 to 35 ºC with an interval of 5 °C in the absence and presence of metal complexes such as [Cr(acac)2(H2O)2]Cl, K3[Fe(C2O4)3] and (NH4)4[Co(C6H5O7)2] at concentrations ranging from 2.0 × 10-4 to 8.0 x 10-4 M. The specific conductance rapidly increased at the pre-micellar region with increasing of temperature and concentration of SDS, but after critical micelle concentration (CMC) the rate of increase was slower. As the concentrations of metal complexes [Cr(acac)2(H2O)2]Cl, K3[Fe(C2O4)3] and (NH4)4[Co(C6H5O7)2] increased, the CMC of SDS decreased exponentially, which was sharp with increasing temperature. The CMC decreases due to the formation of pre-micellar aggregates of the positive counter ions of the complexes with dodecyl sulphate ions (DS-) and hydrophobic interaction between ligands of complexes and hydrophobic tail of SDS. The pre-micellar aggregate formation was essentially influenced by the counter ions binding abilities to the anionic micelle. The effect of metal complexes on lowering the CMC of SDS was found to follow the order [Cr(acac)2(H2O)2]Cl < K3[Fe(C2O4)3] < (NH4)4[Co(C6H5O7)2]. Thermodynamics of metal complexes with SDS and parameters of micellization ΔG°mic, ΔH°mic and TΔS°mic  were calculated.Keywords:  Surfactants; Sodium dodecyl sulphate; Critical micelle concentration; Pre-micellar aggregate; Hydrophobic interaction.© 2011 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved.doi: http://dx.doi.org/10.3329/jsr.v4i1.7989J. Sci. Res. 4 (1), 135-141 (2012) 


BIBECHANA ◽  
2012 ◽  
Vol 8 ◽  
pp. 37-45 ◽  
Author(s):  
Sujit Kumar Shah ◽  
Tulsi Prasad Niraula ◽  
Ajaya Bhattarai ◽  
Sujit Kumar Chattarjee

Precise measurements on the specific conductivity of cationic surfactant (Dodecyltrimethyl ammonium bromide) and anionic surfactant (Sodium Dodecyl Sulphate) in methanol water mixed solvent media containing 0.1, 0.2 and 0.3 volume fractions of methanol are reported at 308.15 K. Specific conductivities of Dodecyltrimethyl ammonium bromide and Sodium Dodecyl Sulphate increase with increase in concentration and decrease with increase in the volume fractions of methanol.  Critical micelle concentration (cmc) increases with increase in volume fraction of methanol in case of both surfactants. Free energy of micellization (ΔGºm) has been calculated. Increase in cmc with increase in volume fractions of methanol has been explained in terms of breaking of structure of water due to co-solvent effect.Keywords: Critical micelle concentration; methanol-water mixed solvent media; Specific conductivity; Dodecyltrimethylammonium Bromide; Sodiumdodecyl SulphateDOI: http://dx.doi.org/10.3126/bibechana.v8i0.4883  BIBECHANA 8 (2012) 37-45


1985 ◽  
Vol 78 (1) ◽  
pp. 205-231 ◽  
Author(s):  
R. Crossley ◽  
D. Holberton

The giardins are a family of approximately 30000 Mr structural proteins found in microribbons attached to microtubules in the disc cytoskeleton of Giardia. After examining the solubility of giardins in various agents, a method has been developed to extract these polypeptides and subsequently precipitate them selectively. The giardin chains are soluble in 10 mM-HEPES/EDTA buffer at high pH and low ionic strength, but become insoluble in 10 mM-MES/EDTA buffer at pH 6.7 when the ionic strength is raised above 50 mM salt. By dialysing giardin extracts in turn against dissociating and reassembly buffers, the purification is obtained of a subset of giardin chains identified by sodium dodecyl sulphate/polyacrylamide gel electrophoresis as the cytoskeleton bands 14a, 14b and 15. The structures forming under assembly conditions are all composed of fine filaments, 2–3 nm in diameter. Filaments after the first cycle of assembly are found in bundles, narrow ribbons of two or three filaments, and large ordered tactoids. Assembly after a second cycle of solubilization yields a more uniform population of long ribbons. Both the tactoids and the second cycle ribbons are transversely banded at the 15 nm interval characteristic of microribbons in the cytoskeleton. Filaments in the tactoids are precisely placed at a centre-to-centre separation of 2.5 nm. Other structural features of the tactoids are discussed in relation to the association behaviour and possible dimensions of the giardin molecular subunit.


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