Cleaning glass tubes

Extraction of sediment samples. Prior to extraction, sediment samples were freeze-dried and homogenized. Approximately 10 g of dried sediment were placed in a preextracted thimble, and a small piece of silanized glass wool was placed in the thimble on top of the sample to prevent sediment parts from leaving the thimble. The thimble was placed in a Soxhlet setup and extract for 16 h (overnight) with 200 ml hexane/acetone (3/1 v/v). The extracts were concentrated in the rotation evaporator until approximately 5 ml (/ = 0.05 bar T = 40°C) of extract remained. If the extraet still contained solid particles, the extract was filtered with diatomaceous earth or sodium sulfate. The extract was transferred to a diatomaceous earth- or sodium sulfate-filled funnel and flushed with 10 ml hexane. The eluted extract was evaporated again in the rotary evaporator until approximately 5 ml of extract remained. The extract was transferred to a cleaned glass tube and concentrated until near dryness. The dried extract was finally redissolved in 3 ml hexane. 

Early observations showed that blood clotted faster in clean glass tubes than in siliconized glass. When Mr. Hageman s blood failed to clot in vitro, it was speculated that a Hageman Factor was responsible for the in vitro activation of blood coagulation (see Ref. 2) for a delightful account). 

Add 2 ml methanol and centrifuge at 1000 x g, room temperature. Remove the supernatant using a Pasteur pipet and place in a clean glass tube. 

Chromatography columns—25 pieces 5- to 8-mm inside diameter clean glass tubing approximately 15 in. long, or 50 equivalent chromatography columns. 

If there is a considerable amount of residue in the Claisen flask a third fraction is distilled, using the same precautions as before. Finally, when the distillation is completed, the capillary is removed at once and cleaned by placing it carefully in a test tube containing 5 ml of acetone. Insert a piece of clean glass tubing in the rubber tube and draw the acetone a few times upwards to about the middle of the tube. Clean the Claisen flask according to the usual procedure. Hand the distillate to the instructor with the note book and report. 

Transfer the aqueous (upper) phase to clean glass tubes using a Pasteur pipette. This phase contains the clodronate. Do not take the interphase. 

Figure 32. Photograph demonstrates the antithrombogenic character of a glow discharge-cleaned glass tube after being implanted in the canine thoracic inferior vena cava for 479 days. ...

Milk samples are placed in clean glass tubes, flushed with nitrogen or argon, and closed, preferably with a screw cap. After proper labeling, they can be stored for several months at or below — 20°C in the frozen state without significant deterioration. 

Transfer 500 pL of each sample, control, standard, and blank to a clean glass tube. 

Water in a glass tube that contains grease or oil residue displays a flat meniscus (left), whereas water in a clean glass tube displays a concave meniscus (right). Explain this observation. 

Flow measurements using nonintrusive or low mechanical ac tion principles are desired, such as magnetic, vortex-shedding, or Coriolis-type flowmeters. Orifice plates are easy to use and reliable but have a limited range and may not be suitable for streams which are not totally clean. Rotameters with glass tubes should not be used. 

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