Cellulose nitrate membrane

Reszka et al. [168] used ultrahltration to separate free mitoxantrone from PBCA nanoparticles. The particle suspension was passed through a cellulose nitrate membrane with a pore size of 20 nm with magnetic stirring and pressurized nitrogen. The filtrate obtained was analyzed for free drug content. Recovery of the particles is not possible with... 

Acetylcholineesterase and choline oxidase Enzyme membrane in H20 was treated with 11% solution of PVA-SbQ (polyvinyl alcohol) with styryl pyridinium groups. Mixture was spread on a cellulose nitrate membrane and air dried. The membrane was exposed to UV radiation for 3 h and stored at 4°C. The enzyme membrane was fixed with a Pt electrode. Sample was dissolved in phosphate buffer and measured. The best results were obtained at pH 8 and at 30°. The calibration graph was rectilinear for 5mM ACh. The storage stability of the dry membrane was excellent. [77]... 

Collection of metal complexes of the analytes on suitable adsorbing materials is often employed as an enrichment step in combination with flame methods. In a procedure proposed by Solyak et al. [20], five metals [Co(II), Cu(II), Cr(III), Fe(III), and Pb(II)] were complexed with calmagite 3-hydroxy-4-[(6-hydroxy-m-tolyl)azo]-naphthalenesulfonic acid and subsequently collected on a soluble cellulose nitrate membrane filter. In this way an effective separation from alkaline and alkaline earth metals was achieved, based on the differences in their complex formation constants and those of the transition elements. The experimental parameters were optimized for the quantitative recovery of the elements. After hot dissolution of the filter with HNO3, the analytes were determined by FAAS. Minimum detectable concentrations ranged from 0.06 pg l-1 for Cu to 2.5 pg l-1 for Cr. 

M. Soylak, U. Divrikli, M. Elci, M. Dogan, Preconcentration of Cr(III), Co(II), Cu(II), Fe(III), and Pb(II) as calmagite chelates on cellulose nitrate membrane filter prior to their flame atomic absorption spectrometric determination, Talanta, 56 (2002), 565-570. 

T. M. (2002) Qualification of cellulose nitrate membranes for lateral-flow assays. IVD Technol. 

Figure 1.6 SEM of the surface of a microporous cellulose nitrate membrane prepared by precipitation from a homogeneous polymer solution by water vapor precipitation.

With the help of Professor Dr. Zsigmondy, who was Director of the Institute of Colloid Chemistry of the University of Goettingen, Sartorius-Werke Aktiengesellschaft developed a commercial process for making cellulose nitrate membranes. The membrane was known as the "Zsigmondy Membranfilter." Commercial production began in 1927, but sales were largely confined to the laboratory market. 

Sun H, Liu S, Ge B, Xing L, Chen H. Cellulose nitrate membrane formation via phase separation induced by penetration of nonsolvent from vapor phase. J Membr Sci. 2007 295(l-2) 2-10. 

Poncelet, B., Poncelet, D., and Neufeld, R. J., Control and mean diameter and size distribution during formulation of microcapsules with cellulose nitrate membranes. Enzyme Microb. TechnoL, 11,29-37, 1989. 

Wu et al. (1992) treated the surfaces of the hydrophilic porous membranes, such as cellulose acetate, by radiation graft polymerization of styrene to increase their hydrophobicity and to reach the MD membrane characteristics. Kong et al. (1992) employed a cellulose nitrate membrane modified via plasma polymerization of both vinyltrimethylsilicone and carbontetrafluoride and octafluorocyclobutane for the preparation of MD membranes. Fujii et al. (1992) prepared tubular membranes from PVDF polymer dopes by using the dry-jet wet-spinning technique. Ortiz de Zarate et al. (1995) and Tomaszewska (1996) reported on PVDF flat-sheet membranes prepared for MD by the phase inversion method. 

As noted above, flow FFF is not limited to aqueous systems. Using a solvent-compatible cellulose nitrate membrane, we have shown that polystyrenes can be fractionated in an ethylbenzene carrier by flow FFF, as shown in Figure 8.16. The universal scope of flow FFF is further confirmed by noting that this subtechnique has been applied to samples as varied as virus particles, silica colloids, polystyrene beads, humic materials, proteins, and protein aggregates. 

Southern blot a method for transferring fragments of DNA from electrophoresis gels to cellulose nitrate membranes, first described by E.M. Southern [/. Mol. Biol. 98 (1975) 503-517]. Similar prixtedures for replicating electrophoretograms of RNA or proteins have been capriciously named Northern or Western blots, respectively. As yet, there is no Eastern blot. 

Fig. 1. (left) Effect of poly(ADP-ribose) on DNA-histone complex formation. 40 ng samples of rat liver [ P]DNA were incubated with increasing concentrations of unlabeled poly(ADP-ribose) in 10 mM Tris-HCl (pH 7.0), 150 mM NaCl, 3 mM EDTA at22°C for 10 min. After addition of 20 ng histone HI, H3 or H4, respectively, and 10 min incubation in a final volume of 150 ul, the mixtures were placed on cellulose nitrate membrane filters, washed, and the amount of retained complexes measured. Other conditions as in (3). 

A collodion is a solution of cellulose nitrate (4 %) in a mixture of alcohol and ether. The cellulose nitrates increase the viscosity of the alcohol-ether mixture. After evaporation of the solvents a stiff cellulose nitrate membrane remains on... 

Micro-organisms replicate only in the presence of water. The activity of preservatives depends therefore on the concentration of the free and active form in the aqueous phase of the preparation. Free refers to the binding that some preservatives can have with active substances, excipients or packaging materials. Examples of the binding of preservatives are the adsorption of phenylmercuric compounds to rubber stoppers, the adsorption of benzalkonium chloride to silicon rubber tubes and to cellulose nitrate-membrane filters, the solubilisation of methyl parahydroxybenzoate by polysorbate 80 [49] and by sodium lauiyl sulfate [50] and the migration (distribution) towards the lipid phase of methyl parahydroxybenzoate in emulsions. 

Preparation of Stock Solutions of Amphiphiles. Stock solutions for SAM formation were prepared by dissolving the ODP in a 100 0.4 (vA ) mixture of 7i-heptane and propan-2-ol at concentrations of 5, 50, and 500 fjM, followed by sonication for 10 min. For comparison purposes, a 500 fjM solution was also prepared in pure propan-2-ol (ODP was found to be insoluble in pure /i-heptane). The resulting solutions were filtered through a 200 nm cellulose nitrate membrane and stored at ambient temperature in glass bottles until use. No deleterious effects were observed upon storage of these solutions for up to several weeks. 

Diagnostic Appiications. The binding characteristics of cellulose nitrate membranes have led to their use in numerous biosensor applications, such as in an electrochemical microbial biosensor for EtOH (85) and in glucose oxidase based glucose sensors (86). Cellulose nitrate continues to play an important role in the development of new biosensors as both a solid support and a method for removal of unboimd reagents (87-93). 

The thermo-oxidative degradation erf nitrocellulose in aprotic solvents has been examined. Cellulose nitrate membranes have been used to encapsulate p-D-galactosidase. Characteristics of the semi-permeable membranes obtained from the system cellulose nitrate-methanol-dioxan-barium perchlorate have been investigated. These membranes may find use in the construction of artificial kidneys. 

Silicone oils SOSO (viscosity 0.55 P), SOlOO (viscosity 1.18 P), and SO500 (viscosity 5.58 P) purchased from PROLABO are used in these spreading experiments. The cellulose nitrate membrane Qlters purchased from Sartorius (type 113) with an average pore size of 0.2 and 3 pm, respectively, are used as porous layers. All membrane samples used are plane circular plates with a radius of 25 mm and thickness from 0.0130 to 0.0138 cm. The porosity of the membranes ranges between 0.65 and 0.87. Prior to spreading experiments, membranes were dried for 3-5 h at 95°C and then stored in dry atmosphere. 

A rectangular membrane sample 1.5 cm 3 cm was used. Porous samples were cut from the cellulose nitrate membranes purchased from Millipore of Billerica, MA. Three different membranes with averaged pore size were used 0.22 pm, 0.45 pm, and 3.0 pm. Each membrane sample was immersed 0.1-0.2 cm into a liquid container, and the position of the imbibition front was monitored over time. 

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