Methanol-chloroform, sodium dodecyl

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). 

The ion pair extraction by flow injection analysis (FIA) has been used to analyze sodium dodecyl sulfate and sodium dodecyl ether (3 EO) sulfate among other anionic surfactants. The solvating agent was methanol and the phase-separating system was designed with a PTFE porous membrane permeable to chloroform but impermeable to the aqueous solution. The method is applicable to concentrations up to 1.25 mM with a detection limit of 15 pM [304]. 

Since the early delipidation procedure was applied initially to the whole serum (815) and later to the isolated serum lipoproteins (818), many other methods of delipidation have been reported [see reference (816) for review], employing mixtures of organic solvents (ethanol-ethyl ether chloroform-methanol, acetone, etc.) or detergents (sodium dodecyl or decyl sulfate, Triton X-100, Nonidet, etc.). Techniques for delipidation have not been standardized, nor is there a comprehensive comparative assessment of the various proposed methods presently avail-... 

Materials. Sodium dodecyl sulfate was supplied by Aldrich Chemical Company, Milwaukee, WI, and various alkyl alcohols were obtained from Supelco, Inc., Bellefonte, PA, with purity greater than 99%. For microemulsion preparation, sodium stearate (>> 99% pure) was supplied by Matheson, Coleman and Bell, Inc. and sodium myristate was supplied by K K Laboratories, Inc. All the oils (>> 99% pure) were obtained from Chemical Samples Company. Double-distilled water was used in all experiments. For monolayer studies, the 4.0 mM solutions of all pure alkyl alcohols were prepared in a mixture of methanol, chloroform and n-hexane in a volume ratio 1 1 3. 

A membrane-derived a-amylase was solubilized from membrane vesicles by treatment with Triton X-100 and was highly purified by chromatography on an anti-a-amylase-protein A-Sepharose column. Membrane-derived a-amylase was indistinguishable from the soluble extracellular enzyme by sodium dodecyl sulphate-gel electrophoresis and radioimmunoassay. The membrane-derived enzyme contains phospholipid. Approximately 30 to 80% of the phospholipid was extracted from the purified enzyme by chloroform-methanol. The extracted phospholipid was predominantly phosphatidylethanolamine. Treatment with phospholipase D released phosphatidic acid. Membrane-bound a-amylase was latent in membrane vesicles. Release of membrane-bound a-amylase from vesicles by an endogenous enzyme was maximal at pH 8.5, was inhibited by metal chelators and di-isopropyl fluorophosphate and was stimulated by Ca and Mg. The amount of membrane-bound a-amylase was related to the level of secretion. 

Methylene blue (Cat. No. 6040), sodium sulfate (anhydrous. Cat. No. 6643), sulfuric acid (95-98%, Cat. No. 713), chloroform (Cat. No. 2445), and methanol (Cat. No. 6009) were obtained from Merck. Sodium dodecyl sulfate (Cat. No. L-5750) was purchased from Sigma. Safe-lock Eppendorf cups, 2.0 ml (Cat. No. 0030 120.094) and 1.5 ml (Cat. No. 0030 120.086), from Eppendorf Geratebau, Netheler + Hinz, were obtained through Mitlacher. 

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