Centrifugal Filter Developments

1984 Centrifugal S aration, in Mathematical Methods in SLS. A. Rushton (Ed.), Nato ASI Series Appl. Sci No. 88. Kluwer, Dordrecht. 

Ambler, C.A., 1979, Sect. 4.5, Handbook of Separation Tediniques, P.A, Sdiweitzer (Ed.), McGraw Hill. 

Huhsch G. and Wilkesmann, K, 1977, Ch p. 12. Sohd liquid Separation Equ ment Scale-Up, D. Purchas and R Wakeman (Eds), Uplands Press, Croydon. 

Purchas, D.B., 1981, Solid-Liquid SeparartLon Technology, Uplands Press. U.K., 241. Quilter, J.A, I.Ch.E., N. W. Branch Symp., No. 3, Section 7. 

Records, F.A., 1990, CeatrifUgal Sedimentation Lou borough University Short Course Notes. 

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The electric motors are often the noisiest component of the centrifuge assembly. Most standard motors in the 75—250 kW range develop noise levels of 85 dbA (weighted sound pressure level using filter A, per the ANSI standard). A quiet motor can reduce this level by 5 dbA and should be used whenever noise is of concern. 

In fine chemicals manufacture, batch filtration prevails. This operation is the subject of R D in various steps of process development. The aim of R D on filtration is (1) to establish an effective procedure of filtration and washing providing a filter cake and/or filtrate of desired quality, and (2) to select the most appropriate filter or centrifuge for full-scale operation and determine its productivity. The productivity is defined as ... 

Organic solvent extraction. Two analytical methods for acetamiprid have been developed One method is for the parent only and the other determines the total residue of the parent and its metabolites (lM-1-2, lM-1-4 and lC-0). Air-dried soil (20-g equivalent dry soil) is weighed into a centrifuge tube and imidacloprid residue is extracted with 100 mL of methanol-0.1M ammonium chloride (4 1, v/v) using a mechanical shaker for about 30 min. After shaking, the tube is centrifuged at 8000 rpm for 2 min. The supernatant is filtered and the analysis of the soil residue is carried out in the same manner as described above for the parent compound. 

Improved Methods for Collection, Bioassay, Isolation, and Characterization of Compounds. Techniques used to characterize natural products are evolving rapidly as more sophisticated instrumentation is developed. Plant physiologists and chemists should work closely together on this aspect, since rapid and reproducable bioassays are essential at each step. There is no standard technique that will work effectively for every compound. Briefly, isolation of a compound involves extraction or collection in a appropriate solvent or adsorbant. Commonly used extraction solvents for plants are water or aqueous methanol in which either dried or live plant parts are soaked. After extracting the material for varying lengths of time, the exuded material is filtered or centrifuged before bioassay. Soil extraction is more difficult, since certain solvents (e.g. bases) may produce artifacts. 

Transfer the solution to a centrifuge tube and centrifuge down to a loose 5 mL pellet. We recommend a medium speed for 10 min. Decant off excess liquid. (Note Miller and Scholin [6] developed a system using a filter tube and filtration manifold that reduces sample processing time and causes less cell damage than centrifuging.)... 

For the assay of a-D-mannosidase, the incubation mixture employed in our laboratory contained 0.5 ml of M acetate buffer at a pH appropriate for the particular enzyme preparation, 1.5 ml of 16 mM p-nitrophenyl a-D-mannopyranoside, 1.5 ml of water (which could be replaced by other additives as required), and 0.5 ml of suitably diluted, enzyme preparation. After 1 hour at 37°, the reaction was terminated, and the color was developed by adding 4 ml of 0.4 M glycine-sodium hydroxide buffer, pH 10.5. The mixture was centrifuged for 15 minutes at 1500 g, and the color intensity of the liberated p-nitrophenol (25-150 fig) in the supernatant liquor was measured on a Spekker photoelectric absorptiometer, with use of Ilford No. 601 violet filters having maximal transmission at 430 nm, and a 1-cm light path. Separate control-experiments for enzyme and sub-... 

The following method has therefore been developed after the cyclonite has been filtered off, the spent acid is cooled to — 12°C. Ammonium trinitrate is then crystallized, separated in a centrifuge and recycled to the nitrator. After centrifuging the acid contains 10% of cyclonite and a considerable amount of ammonium nitrate. It is further processed so as to yield cyclonite, nitric acid being converted into ammonium nitrate. 

A method capable of quantifying SPC in raw bovine milk was developed. In this procedure the sample was centrifuged at -4°C and the top fat layer removed. The defatted milk was depro-teinated with TCA, and the supernatant was washed sequentially with dichloromethane, hexane, and ethyl acetate. An aliquot of the separated aqueous layer was prepared for the HPLC analysis by mixing with DSA and filtering. The analyte was quantified with an electrochemical detector. Recoveries achieved were 76-80% (116). 

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