Membrane filtration tests

A minimum of ten negative product control containers may be adequate to simulate manipulations by the operator during a membrane filtration test. An equivalent number of samples to the test samples may be necessary to simulate the manipulations of the product by the operator during a direct inoculation test. 

Tests should also be done in the presenee of organic matter (e.g. albumin) and in hard water. It is important to remember when performing viable counts that care must be taken to ensure that, at the moment of sampling, the disinfection process is immediately arrested by the use of a suitable neutralizer or ensuring inactivation by dilution (Table 11.4). Membrane filtration is an alternative procedure, the principle of whieh is that treated cells are retained on the filter whilst the disinfectant forms the filtrate. After washing in situ, the membrane is transferred to the surface of a solid (agar) reeoveiy medium and the eolonies that develop on the membrane are counted. 

Sterile pharmaceutical preparations must be tested for the presence of fungal and bacterial contamination before use (see Chapters 18 and 23). If the preparation contains an antibiotic, it must be removed or inactivated. Membrane filtration is the usual recommended method. However, this technique has certain disadvantages. Accidental contamination is a problem, as is the retention of the antibiotic on the filter and its subsequent liberation into the nutrient medium. 

The purpose of a sterility test is to determine the probable sterility of a specific batch. The USP lists the procedural details for sterility testing and the sample sizes required [1], The USP official tests are the direct (or culture tube inoculation) method and the membrane filtration method. 

The prototype shell-and-tube type cross-flow filtration modules (Pall Corp.) used for filtration tests are welded into a stainless steel shell enclosure. The modules have an inlet (filtrate) and outlet (retentate) port (both at tube sides) with Vi-inch tubing ends, and a permeate port, located near the midpoint of the shell side of the unit. The stainless steel filter membranes have a nominal pore size of 0.1 pm. The surface of the filter media is coated with a proprietary submicron layer of zirconia. 

Various membranes are in common use for the filtration of blood during dialysis. In this investigation cellulosic (Cuprophan) and synthetic (acryl nitrile, SPAN) capillary membranes were tested. The fluorine gas treatment was performed as described before. Three parameters are chosen for the assessment... 

A simple assay for the detection of the malarial parasite Plasmodium falciparum involves saponin lysis of blood sample and membrane filtration followed by amplification of the consensus sequence of eight 21-bp repeats. This procedure has been successfully used in the field (F2). A PCR assay targeting kinetoplast DNA sequences of Leishmania species was also successfully tested in the field (F2). Molecular methods for the detection of toxoplasma gondii and several other parasites have been reviewed (F2). 

Thus, one test (ASTM D893) covers the determination of pentane- and toluene-insoluble constituents in used lubricating oils using pentane dilution and centrifugation as the method of separation. The other test (ASTM D4055) uses pentane dilution followed by membrane filtration to remove insoluble constituents larger than 0.8 p,m. 

Tests should also be carried out for sediment if the naphtha has been subjected to events (such as oxidation) that could lead to sediment formation and instability of the naphtha and resulting products. Test methods are available for the determination of sediment by extraction (ASTM D473, IP 285) or by membrane filtration (ASTM D4807 IP 286) and the determination of simultaneously sediment with water by centrifugation (ASTM D96, D1796, D2709, D4007 IP 373, 374). 

Today nnmerous membrane filtration rmits for removal of dissolved dyes such as reactive dyes are in full-scale operation. The treatment of the remaining concentrates still remains difficult. At present the following have been proposed in the hterature and tested in foil-scale operation ... 

Validation of membrane filtration and direct inoculation sterility test methods... 

Total aerobic viable count per standard test method (provide reference number) using membrane filtration method. Sample 100 ml shall be filtrated and placed on low-nutrient content media, at 20 to 22°C for 5 days and observed for another 2 days. 

Microbial recovery studies of membrane filtration method challenged with less than 100 CPU of each organism listed in USP-25, EP-2002 and in-house microbial isolates. Two lots of (Product Name) (Batch Numbers) have been validated in triplicate for each organism. Validation mimicked the test proper in every detail, such as in the volumes of media used, quantities and dilutions of product and diluents. 

Product Name) can be tested for sterility by membrane filtration with 3 X 300 rinsing fluid A after incubation of 14 days and more than one week. 

All tested organisms showed conform results for (Product Name) using membrane filtration technique and rinsed with 3 x 300 ml of fluid A. 

The purpose is to assure that the recommended disinfectant has the acceptable relative standard of the antimicrobial activity using the membrane filtration technique and surface testing technique. 

The membrane filtration technique is used once, prior to the introduction of a new disinfectant within the production department. The surface testing technique is used prior to any changes in the recommended procedure for evaluating its effectiveness on surfaces to be treated and demonstrating activity against contamination for various contact times. 

Standard Test Method (STM) , Membrane filtration method, using... 

ASTM D-4055-04. Standard Test Method for Pentane Insolubles by Membrane Filtration. 

Materials. The silver composition of the present invention comprised 10 ppm silver in water. The silver composition was evaluated employing a liquid to liquid matrix against Mycobacterium bovis BCG (TMC 1028). This organism causes tuberculosis in animals and can cause tuberculosis in humans. It is used as a stand-in for M. tuberculosis, the major cause of human tuberculosis, as tests have shown it to have a similar susceptibility to M. tuberculosis. The test organism was exposed to the silver composition in duplicate at four exposure times and quantified using membrane filtration. 

However, it can be assumed for most electrochemical applications of ionic liquids, especially for electroplating, that suitable regeneration procedures can be found. This is first, because transfer of several regeneration options that have been established for aqueous solutions should be possible, allowing regeneration and reuse of ionic liquid based electrolytes. Secondly, for purification of fiesh ionic liquids on the laboratory scale a number of methods, such as distillation, recrystallization, extraction, membrane filtration, batch adsorption and semi-continuous adsorption in a chromatography column, have already been tested. The recovery of ionic liquids from rinse or washing water, e.g. by nanofiltration, can also be an important issue. 

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