Filters, micro Whatman

Cellulase-gamanase solution - add nine volumes of cellulase solution to one volume of the gamanase preparation and mix thoroughly. Filter through a Whatman GF/A glass micro-fibre filter circle held in a Hartley type three-piece funnel. 

Whatman Glass Micro Filters (TABLE 3 continued)... 

Nine kinds of sampling paper/cards were used. FTA Elute (Micro), FTA DMPK-B, FTA DMPK-A, Indicating FTA (pink), FTA Plant, Blood Stain, Protein Saver 903 (previously Guthrie Card or Schleicher Scheull Card in different times), and 31 ET were from Whatman (now GE Healthcare, Piscataway, NJ, USA) and VWR 237 filter paper from VWR International (West Chester, PA, USA). 

The procedure developed by Bradfield and Cooke is an example of an extraction procedure used for the 1C determination of anions in plant materials.Here, the extraction of anions from 100 mg of fresh plant material (nondried rape) was carried out with 5 ml of deionized water at 70°C for 30 min, followed by filtration through Whatman No.541 filter paper, prior to analysis using ion-pair RP-HPLC. Slightly modified procedures followed by micro-filtration have been used for the determination of inorganic anions, including phosphate, in dried potatoes, coffee beans and tea, tomato, pumpkin, turnip, and lettuce leaves, and spinach. A more unusual extraction solution of... 

Filter pipettes and micro filtration devices are available commercially. Thus, the Whatman syringe filters No. 402/0803/06 (with 4 mm effective diameter) and 402/0805/06 (with 13 mm effective diameter) are suitable for micro- or semimicro-work respectively. 

If neutral or weakly acid solutions are to be examined, the following procedure may be used for the detection of barium and strontium in a micro drop. One drop of 0.5 % sodium rhodizonate solution is placed on Whatman filter paper No. 1. After the liquid has soaked in, the center of the yellow spot is treated with a drop of the test solution. A brownish or reddish-brown stain appears at once if barium or strontium is present. The fleck is then spotted with 1 or 2 drops of a mixture of equal parts of a saturated water solution of dimethylamine hydrochloride and 95 % ethanol. 

---