Sodium dodecyl-sulfate

Analysis of Reagent Purity commercially available sodium dodecyl sulfate generally contains 1-dodecanol, which3deldsa minimum at the CMC in plots of surface tension vs. concentration. The presence of 1-dodecanol can be detected by an HPLC method. Impurities can also Include surfactant homologs and electrolytes, which yield low surface tension values above the CMC. 

Preparative Methods by sulfation of 1-dodecanol with sulfur trloxlde, followed by neutralization of the resultant dodecyl-sulfurlc acid with sodium hydroxide.  

Handling, Storage, and Precautions harmful if Inhaled or swallowed and is irritating to the eyes and skin should be stored under nitrogen.  

Electrophilic Aromatic Substitution. Micellar SDS has been used as a reaction medium for the chlorination and bromlnatlon of alkyl phenyl ethers T gjj(j phenol by several halogenatlng agents (eq 1). Compared to reactions in H2O alone, theparar.ortho product ratio increased for pentyl, nonyl, and dodecyl phenyl ether, and decreased for anlsole. Enhanced ortho relative to para substitution was obtained with phenol. In each case the observed regios-electivity derived at least in part from alignment of the substrate at the micelle-H20 interface and resultant differential steiic shielding of the para and ortho positions by the micelle superstructure. 

Electrophilic Addition to Alkenes, Hydroxy- and alkoxymercurations of alkenes have been performed in micellar SDS. Hydroxymercuration of (1) with mercury(II) acetate, followed by reduction with sodium borohydride, gave a greatly enhanced yield of (2) in micellar SDS (90%) relative to that obtained in THF-H2O (20-25%) (eq 2). Also, the reactions of (1) and the related limonene gave greater cyclic ether diol product ratios in the SDS environment than in aq THF. Both the enhanced 3delds and ratios were attributed to anisotropic solubilization of the alkylmercurial intermediate in a relatively H2O poor mIceUar microenvironment. The hydroxymercuration of an aromatic diene, /Mliallylbenzene, did not display enhanced chemoselectivlty (mono vs. diol formation) in micellar SDS relative to that obtained in THF-H2O. This result suggests that the mIceUar solubilization sites of aromatic substrates and reaction intermediates are more HzO-rich than those of aliphatic systems. 

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Tetrabutylammonium phosphate Tetramethylammonium hydrogen sulfate Cetyltrimethylammonium hydrogen sulfate Butane sulfonic acid Pentane sulfonic acid Hexane sulfonic acid Octane sulfonic acid Dodecane sulfonic acid 1-Pentane sulfonate, sodium 1-Octane sulfonate, sodium 1-Dodecyl sulfate, sodium... 

Sodium lauryl sulfate, 745. See also Sodium 1-dodecyl sulfate Sodium metaperiodate, 639 Sodium methoxide... 

Fig. 11-15. Variation with time of aqueous sodium dodecyl sulfate solutions of various concentrations (from Ref. 54). See Ref. 56 for later data with highly purified materials.

As an example, Tajima and co-workers [108] used labeling to obtain the adsorption of sodium dodecyl sulfate at the solution-air interface. The results, illustrated in Fig. Ill-12, agreed very well with the Gibbs equation in the form... 

Fig. in-12. Verification of the Gibbs equation by the radioactive trace method. Observed (o) and calculated (line) values for for aqueous sodium dodecyl sulfate solutions. (From Ref. 108.)... 

This form is obeyed fairly well above x values of 5-10 dyn/cm in Fig. Ill-15c. Limiting areas or a values of about 22 per molecule result, nearly independent of chain length, as would be expected if the molecules assume a final orientation that is perpendicular to the surface. Larger A values are found for longer-chain surfactants, such as sodium dodecyl sulfate, and this has been attributed to the hydrocarbon tails having a variety of conformations [127]. 

Surface heterogeneity may be inferred from emission studies such as those studies by de Schrijver and co-workers on P and on R adsorbed on clay minerals [197,198]. In the case of adsorbed pyrene and its derivatives, there is considerable evidence for surface mobility (on clays, metal oxides, sulfides), as from the work of Thomas [199], de Mayo and co-workers [200], Singer [201] and Stahlberg et al. [202]. There has also been evidence for ground-state bimolecular association of adsorbed pyrene [66,203]. The sensitivity of pyrene to the polarity of its environment allows its use as a probe of surface polarity [204,205]. Pyrene or ofter emitters may be used as probes to study the structure of an adsorbate film, as in the case of Triton X-100 on silica [206], sodium dodecyl sulfate at the alumina surface [207] and hexadecyltrimethylammonium chloride adsorbed onto silver electrodes from water and dimethylformamide [208]. In all cases progressive structural changes were concluded to occur with increasing surfactant adsorption. 

Fig. XIII-9. The dependence of the flotation properties of goethite on surface charge. Upper curves are potential as a function of pH at different concentrations of sodium chloride lower curves are the flotation recovery in 10 M solutions of dodecylammo-nium chloride, sodium dodecyl sulfate, or sodium dodecyl sulfonate. (From Ref. 99.)...

Fig. XIII-10. Properties of colloidal electrolyte solutions—sodium dodecyl sulfate. (From Ref. 102a.)...

Xu Z H, Ducker W and Israelachvili J N 1996 Forces between crystalline alumina (sapphire) surfaces in aqueous sodium dodecyl sulfate surfactant solutions Langmuir 12 2263-70... 

Wanless E J and Ducker W A 1996 Organization of sodium dodecyl sulfate at the graphite-solution interface J. Phys. Chem. 100 3207-14... 

Sodium lauryl sulfate (sodium dodecyl sulfate)... 

Description of Method. The water-soluble vitamins Bi (thiamine hydrochloride), B2 (riboflavin), B3 (niacinamide), and Be (pyridoxine hydrochloride) may be determined by CZE using a pH 9 sodium tetraborate/sodlum dIhydrogen phosphate buffer or by MEKC using the same buffer with the addition of sodium dodecyl-sulfate. Detection Is by UV absorption at 200 nm. An Internal standard of o-ethoxybenzamide Is used to standardize the method. 

Before we examine the polymerization process itself, it is essential to understand the behavior of the emulsifier molecules. This class of substances is characterized by molecules which possess a polar or ionic group or head and a hydrocarbon chain or tail. The latter is often in the 10-20 carbon atom size range. Dodecyl sulfate ions, from sodium dodecyl sulfate, are typical ionic emulsifiers. These molecules have the following properties which are pertinent to the present discussion ... 

In a series of experiments at 60 C, the rate of polymerization of styrene agitated in water containing persulfate initiator was measuredt for different concentrations of sodium dodecyl sulfate emulsifier. The following results were obtained ... 

For the investigation of molecular recognition in micelles, adenine derivatives and positively charged (thyminylalkyl)ammonium salts such as shown in Figure 30 were prepared, which were solubilized in sodium dodecyl sulfate (SDS) solutions. Nmr studies have shown that binding occurs in a 1 1 molar ratio in the interior of the micelles as illustrated in Figure 30 (192). 

Fig. 3. Sodium dodecyl sulfate—polyacrylamide gel electrophoretic pattern for molecular weight standards (lane 1) water-extractable proteins of defatted soybean meal (lane 2) purified IIS (glycinin) (lane 3) and purified 7S (P-conglycinin) (lane 4) where the numbers represent mol wt x 10. The gel was mn in the presence of 2-mercaptoethanol, resulting in the cleavage of the disulfide bond linking the acidic (A bands) and basic (B bands) polypeptides of the...

The kinetics of vinyl acetate emulsion polymeriza tion in the presence of alkyl phenyl ethoxylate surfactants of various chain lengths indicate that part of the emulsion polymerization occurs in the aqueous phase and part in the particles (115). A study of the emulsion polymerization of vinyl acetate in the presence of sodium lauryl sulfate reveals that a water-soluble poly(vinyl acetate)—sodium dodecyl sulfate polyelectrolyte complex forms, and that latex stabihty, polymer hydrolysis, and molecular weight are controlled by this phenomenon (116). 

Tailing peaks or longer than expected elution volumes are sometimes caused by low solubility of the protein in the mobile phase. Using a trial-and-error process, select the proper pFf and ionic strength to address this problem. Detergents such as sodium dodecyl sulfate (SDS) are sometimes helpful but, because they change the conformation of many proteins and are difficult to remove from the column should be used only if other methods fail. 

The methacrylic backbone structure makes the spherical Toyopearl particles rigid, which in turn allows linear pressure flow curves up to nearly 120 psi (<10 bar), as seen in Fig. 4.45. Toyopearl HW resins are highly resistant to chemical and microbial attack and are stable over a wide pH range (pH 2-12 for operation, and from pH 1 to 13 for routine cleaning and sanitization). Toyopearl HW resins are compatible with solvents such as methanol, ethanol, acetone, isopropanol, -propanol, and chloroform. Toyopearl HW media have been used with harsh denaturants such as guanidine chloride, sodium dodecyl sulfate, and urea with no loss of efficiency or resolution (40). Studies in which Toyopearl HW media were exposed to 50% trifluoroacetic acid at 40°C for 4 weeks revealed no change in the retention of various proteins. Similarly, the repeated exposure of Toyopearl HW-55S to 0.1 N NaOH did not change retention times or efficiencies for marker compounds (41). 

Shifts in the SEC fractionation range are not new. It has been known for decades that adding chaotropes to mobile phases causes proteins to elute as if they were much larger molecules. Sodium dodecyl sulfate (SDS) (9) and guanidinium hydrochloride (Gd.HCl) (9-12) have been used for this purpose. It has not been clearly determined in every case if these shifts reflect effects of the chaotropes on the solutes or on the stationary phase. Proteins are denatured by chaotropes the loss of tertiary structure increases their hydrodynamic radius. However, a similar shift in elution times has been observed with SEC of peptides in 0.1% trifluoroacetic acid (TEA) (13-15) or 0.1 M formic acid (16), even if they were too small to have significant tertiary structure. Speculation as to the cause involved solvation effects that decreased the effective pore size of the... 

For many proteins, a simple buffer such as 0.1M phosphate, pH 7, produces excellent separations on SynChropak GPC columns. Generally, minimal interaction is achieved when the ionic strength is 0.05-0.2 M. To prevent denatur-ation or deactivation of proteins, the pH is generally kept near neutrality. For denatured proteins, 0.1% sodium dodecyl sulfate (SDS) in 0.1 M sodium phosphate, pH 7, is recommended. 

FIGURE 10.10 Analysis of peptides on SynChopak GPC peptide. Mobile phase 0.1 N sodium phosphate, pH 7. 0.1% sodium dodecyl sulfate. (From MICRA Scientific. Inc., with permission.)... 

Columns can be washed with solvents and solvent combinations suitable to remove adsorbed contaminants. When considering the adsorption of analytes, think not only of the diol functionality, but also of the adsorption to residual silanols. Often, the injection of small amounts (500 /d) of dimethyl sulfoxide removes contamination that has accumulated on the column. Aqueous solutions of sodium dodecyl sulfate, guanidine hydrochloride, or urea are compatible with Protein-Pak columns. 

The polymerization reaction is conducted at the desired temperature with a slow stirring regime for a certain period. A typical recipe for the emulsion polymerization of styrene is exemplified in Table 1 [40]. As seen here, potassium persulfate and sodium dodecyl sulfate were used as the initiator and the stabilizer, respectively. This recipe provides uniform polystyrene particles 0.22 /Lim in size. 

Sodium dodecyl sulfate micelle 71,72,77,79 Spin label 139 Starch 100, 104 —, crosslinked 106 —, graft polymers 105, 107, 125, 127 Styrene 160—162 Styrene-divinylbenzene resins 167 Styrenesulfonic acid, copolymers 74—76 Surface area 147... 

Removal of general organic fouling is best achieved by alkaline cleaning based on caustic, EDTA, and a surfactant such as sodium dodecyl sulfate or sodium lauryl sulfate. 

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