Millipore membranes fluoride

FIG. 20-67 Chemical phase inversion 0.45- lm polyvinylidene fluoride membrane. Courtesy Millipore Corporation.)... 

Immobilon (polyvinylidene fluoride) membrane from Millipore Corp., Bedford, MA. 

This technique is still evolving. The favored approach at present is to submerge a small, known amount of suspension inside a secured Durapore (polyvinylidene fluoride) membrane pouch (Millipore Products, Bedford, MA) of suitable porosity in teabag fashion in a suitable dissolution medium using the USP Method 1 Paddle Apparatus. Optimization of experimental conditions (rate of agitation, volume and type of medium, temperature, etc.) must be established to achieve reproducible results. 

Most synthetic polymers are hydrophobic. However, the surface can be modified through the addition of covalently bonded chemical moities. This process is used to produce the Durapore hydrophilic membrane [Figure 37-10, p. 435], The base polymer is polyvinylidene fluoride the surface is the -OH adduct" (Millipore). 

Two microfiltration membranes (Millipore, hydrophilic (GVWP) and hydrophobic (GVHP)) with nominal pore sizes of 0.22 (tm were used. The hydrophilic membrane is a modified hydrophobic membrane. The hydrophilic membrane was chosen for most experiments because hydrophilic membranes have a reduced adsorption capacity towards hydrophobic organics Qucker and Clark(1994)). The membrane material is a modified polyvinylidene fluoride (PVDF). 

D. Grandine, II (Millipore) Processes of making a porous membrane material from polyvinylidene fluoride, and products. US Patent 4203848, May 1980. 

Sigma Chemical Co. Standard protein solutions were prepared in water. Standard solutions were made for each protein of 10 mg dissolved in 1 L with water. The water was filtered with HA 0.5 xm membranes (Division of Millipore, Waters Co., Milford, Massachusetts, U.S.A.) and deionized prior to use. The extra pure grade solvent of ACN was purchased from Duksan Pure Chemicals Company (Incheon, Korea). TEA was purchased from Sigma Chemical Co. The sample for injection was filtered with 0.45 p.m polyvinylidene fluoride (PVDF) (Waters Co.). Sodium chloride and hydrochloric acid were purchased from Duksan Pure Chemicals Company. Piperazine was purchased from Sigma Chemical Co. For the anion exchange membrane, buffer A was 20 mm piper-azine-HCl, pH 6.4, and buffer B was made by addition of 1 M NaCl to buffer A. The mobile phases for RP-HPLC were as follows buffer A, 0.1% TEA in water and buffer B, 0.1% TEA in ACN. 

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