Filters Sartorius membrane

Burton and coworkers [65] have studied the distribution of arsenic in the Atlantic Ocean. Samples from 1000 m and above were filtered through acid-washed 0.45 xm Sartorius membrane filters. Analyses on samples from depths below 1000 m were made on unfiltered water. 

Although the Millipore Corporation offer a very wide range of filter holders and accessories, other companies provide valuable competition e.g. Andaman Co., Ltd. (Appendix 3) are agents for Schleicher Schuell who manufacture a comparable range of filters and holders etc., and V.A. Howe supply Sartorius membranes and filter holders. 

Membrane filters (Sartorius SM, Synpor, Millipore) made of cellulose derivatives contain varying amounts of impurities and thus, before the sample analysis the given component should be determined in unexposed filters. Such membrane filters are very resistant to water, weak acids and bases, however, they are soluble in ketones, esters and alcohols. Their ashing is often carried out after solution in isopropyl alcohol. 

Filter the solution through Sartorius prefilter and membrane filter 0.2 pm into receiving tanks. 

FIGURE 2 Photo of stack of flat sheet disk membrane adsorbers in a filter holder. (Courtesy of Sartorius Corp.)... 

Fig. 6 10-inch standard filter element with pleated membrane and protection fleeces. (Courtesy of Sartorius AG.)... 

The filters used for filtration were of the types Sartorius depth filter (particle retention size 0.7 pm) and Sartorius PH membrane filter capsule (particle retention size 0.45 pm). Polyethylene bottles produced by Nalgene were used for each of the reference material. 2600 pieces of 500 mL bottles were cleaned, using the following procedure ... 

Xylene Baker Analyzed ACS and n-Heptane Baker Analyzed were purchased from J. T. Baker (Mallinckrodt Baker Inc., Phillipsburg, NJ). Membrane filters in Regenerated Cellulose (0.45 pm, 0 47 mm, type 184) were obtained from Sartorius AG (Goettingen, Germany). 

A number of companies sell the equipment and also sterile dehydrated pads of selective media for use with membrane filters. These only need the addition of sterile water before use. The most important suppliers in the UK include companies such as Gelman, Millipore, and Sartorius. 

Membrane filters were first commerciafised in 1927 by the Sartorius Company in Germany using the Zigmondy process. Reverse osmosis (RO) was first observed and studied in the 1920s. However, it remained unnoticed until rediscovered by Reid and his co-workers 30 years later. The first practical phenomenon of haemodialysis was demonstrated by Kolff in the 1940s. Membrane milestones are given in Table 1.1. 

For the anion exchanger experiment, a gradient mode with change in NaCl concentration was used to separate whey proteins of a-lactalbumin, 3-lactoglobulin, and BSA. The protein standards were used and the strong anion exchange membranes used in this experiment were CIM QA (BIA Separation Co.), QlOO (Sartorius), and HiTrap Q (Pharmacia). The mobile phases were buffer A (20 mm piperazine-HCl, pH 6.4) and buffer B (buffer A. + I M NaCl). In this experiment, the sample of whey was injected only with filtered 0.45 pm PVDF, without... 

Liquid-Membrane Electrodes. The electroactive phase in this type of electrode consists of a liquid that has been stabilized mechanically. For this purpose the electroactive components may be dissolved in a highly viscous and apolar organic solvent such as one of the higher alcohols or paraffin. A porous material (e.g., commercial membrane filters such as Sartorius cellulose nitrate with pore diameters of about 0.45 pm), are initially made hydrophobic with, e.g., hexamethyl disilazane and then soaked with this solution and introduced in place of the solid membrane in an electrode of the type described above. More frequently, however, the liquid is not fixed in a porous material, but rather embedded into a high molecular mass polymer like PVC. In this case the plasticizer (normally present at a concentration of about 66% by weight) acts as a solvent for the electroactive component (the concentration, which seldom exceeds 1 % ). Simplified construction schemes for these two types of electrodes are illustrated in Figure 13. 

Silicone oils SO20 (viscosity 0.218 P), SOSO (viscosity 0.554 P), SOlOO (viscosity 1.18 P), and SO500 (viscosity 5.582 P) purchased from Prolabo, Productos para Laboratorios Quimicos, a Spanish company, were used in the spreading experiments. The viscosity of oils were measured using the capillary Engler Viscometer VPG-3 at 20 0.5°C. Cellulose nitrate membrane filters purchased from Sartorius (type 113), with pore size 0.2 and 3 pm (marked by the supplier). 

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