Centrifugation tubes

General Considerations. With liquids and solutions the most serious losses are due to (a) transference from spherical flasks and difficulties of drainage, (b) retention by filter-papers, (c) absorption by large corks. As containers for small quantities of liquids it is therefore often convenient to use pear-shaped flasks A and conical test-tubes or centrifuge-tubes B (Fig. 29). (In this and subsequent figures, approximate dimensions are given to indicate a convenient size.)... 

The complete filtration apparatus is shown in Fig. 5, p. 11. A simpler and cheaper apparatus is shown in Fig. 45. This consists of a boiling-tube A having a side-arm for connection to the pump the tube A is conveniently held in a wooden or cork block B or in a clamp. The funnel F may be fitted into A through a pliable rubber disc D the latter is more useful than a cork since it covers tubes of various diameters. The filtrate is collected in the centrifuge-tube T. 

As a general rule, when working with semimicro quantities, it is best to employ pear shaped vessels (Fig. XII, 1, 1, a) and centrifuge tubes (Fig. XII, 1, 1, 6) as containers for liquids convenient capacities are 6, 10 and 20 or 26 ml. for flasks, and 1, 3, and 6 ml. for centrifuge tubes. Round-bottomed vessels of similar volumes... 

As a general rule flasks and similar vessels should be heated in an air bath (compare Fig. II, 5, 3). A glycerol bath may be employed for temperatures up to 140° the glycerol is subsequently removed from the outside of the vessel by washing with water. Medicinal liquid paraffin may be used for temperatures up to about 220° hard hydrogenated cotton seed oil, Silicone fluids or fusible metal may be employed when higher temperatures are required. Small test-tubes and centrifuge tubes... 

A Pyrex micro filter (Fig. XII, 2, 18) of 8 ml. capacity and furnished with a sintered glass disc is useful for the filtration of hot or boihng hquids. The long cylindrical tube reduces evaporation. The filter may be inserted into a test-tube with side arm (Fig. XII, 2, 13) and the filtrate collected in a centrifuge tube or semimicro test-tube receiver. 

Carefully scrape the separated bromophenol blue spots on to a sheet of clean smooth-surfaced paper using a narrow spatula (this is easier if two grooves are made down to the glass on either side of the spots). Pour the blue powder into a small centrifuge tube, add 2 mL of ethanol, 5 drops of 0.880 ammonia solution, and stir briskly until the dye is completely extracted. Centrifuge and remove the supernatant blue solution from the residual white powder. Repeat this procedure with the separated Congo red and phenol red spots . 

To 2 mmol of freshly prepared ethereal LiCu(C.H3), are added 154 mg (1 mmol) of ( — )-m-5-melhyl-2-cyclo-hexenyl acetate (3a). [a]25 —2.7 (c = 3, CHC1,), in a centrifuge tube at 0°C. The mixture is kept at 0 °C for 8 h after which 1 mL of water is added. Methane is evolved and a reddish precipitate forms. After centrifuging, the supernatant liquid is decanted and concentrated, and the product trims-4 is isolated by preparative GC. Isolated yields range from 30% and 40%. However, it was reported in a similar reaction that the yields range from 90% and 95% 5. Analysis by capillary GC shows the product to be 99.5% trans-4 and 0.5% t -4. Capillary GC of the starting 3a shows the acetate 3a to be homogeneous except for a trace ( — 1.0%) of the trans-isomers. 

The supernate is transferred to a clean centrifuge tube, about 20ml of water and 2ml of chromous... 

The app consists of a glass centrifuge tube, 14mm internal diameter, ending at the bottom in a graduated capillary tube, 1 mm internal diameter as shown in Fig 16. A feed- or sample... 

In operation, the centrifuge tube is filled with the sedimentation liq to within 10mm of the top. The feed-tube is then filled with the sample suspension and the upper end is closed by the operator s finger. The feed-tube is then placed in the centrifuge tube with the suspension in contact with the column of clear sedimentation liq this starts the sedimentation. The finger is then removed... 

For anaerobic bacteria, the same principles apply, except that additional attention must be directed to preparing the cell suspensions. Use of an anaerobic chamber in which cultures can be transferred to tightly capped centrifuge tubes is virtually obligatory, and addition of an anaerobic indicator should be used to ensure that subsequent entrance of oxygen does not take place inadvertently. On account of the inserts, screw-capped Oak Ridge tubes are convenient for centrifugation. 

Ultrafiltration processes (commonly UF or UF/DF) employ pressure driving forces of 0.2 to 1.0 MPa to drive liquid solvents (primarily water) and small solutes through membranes while retaining solutes of 10 to 1000 A diameter (roughly 300 to 1000 kDa). Commercial operation is almost exclusively run as TFF with water treatment applications run as NFF. Virus-retaining filters are on the most open end of UF and can be run as NFF or TFF. Small-scale sample preparation in dilute solutions can be run as NFF in centrifuge tubes. 

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