Pore water extraction pressure filtering

Sample preparation Grind yew needles to <3 mm in a blender. Wei out 3-4 g, add 100 mL MeOH, shake for 16 h on a wrist-action shaker, filter (Whatman 1 or 2 paper), wash the solid with 25 mL MeOH. Evaporate the filtrate to dryness under reduced pressure at 40-43°, reconstitute the residue in 10 mL MeOH and 1 mL water. Condition a 47 mm Empore SPE extraction disk (3M Corp.) with 15 mL ethyl acetate, 15 mL MeOH and 15 mL water. Use a 47 mm polypropylene separator with 10 p.m pore size (Gelman 61757) in front of the extraction disk. Pass 10 mL water and 7 mL crude extract throu the disk, wash with 15 mL water, wash with 15 mL MeOH water 20 80,15 mL MeOHrwater 45 55, elute with 20 mL MeOH. water 80 20, filter (2 p,m) the eluate, inject a 10 p,L aliquot. 

What are pore waters and why are their compositions important with respect to the marine geochemistry of the lanthanides The term pore waters (or alternatively, interstitial waters) refers to the waters contained within the pores of sediments. Pore waters are extracted by different types of procedures. Centrifugation and squeezing of sediments are two common methods. The latter is accomplished by using hydraulic systems or gas pressure systems. In all methods the extracted waters are rapidly filtered (typically 0.22 or 0.45 [xm pore size) to yield dissolved matter for analysis. 

The Extrelut cleanup method is suitable for most foodstuffs, such as cheese, yogurt, and other samples that tend to form emulsions during extraction. The prepacked or refilled Extrelut column in a plastic tube consists of a wide-pore kieselgel column. A sample is homogenized in 0.5 N sulfuric acid, diluted with water, and applied onto the Extrelut column for at least 15 min. The absorbed preservatives are eluted with a chloroform - isopropanol (9 1) mixture, and the elu-ate is collected and evaporated carefully nearly to dryness. The last few milliliters of solvent are removed with a gentle flow of nitrogen to prevent substantial losses of BA and SA, which have relatively high vapor pressures. The residue is transferred with methanol into a 10-ml volumetric flask and diluted to volume with methanol. To speed up the dissolution, the use of an ultrasonic bath is recommended. The filtered extract is analyzed on a /zBondaPak Cl8 column, with a... 

In such a case no polarographic response can be observed. An ultrafiltration device allows rapid prior extraction of the unknown interfering substances. The first extraction of the tablet is performed with water, the slurry is filtered under pressure (Millipore vessel and Millipore FH filter 0.5 iJm pore size) and the filtrate is discarded. The extraction proper proceeds with methanol (30 min at 55 C). The interference is caused by competitive adsorption and is minimized at short drop times. 

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