Suction pipette

The asymmetry, in both spatial and spectral content of the absorption characteristics are particularly important when employing the suction pipette approach to measuring in-vivo photoreceptor performance (see Section 5.5.10.3.4), The experimental results are crucially dependent upon the incidence angle of the stimulus irradiation. 

A specialized microelectrode-type electrode was developed by Florey and Kriebel (1966) for use in certain types of neurological recording. The structure is basically a suction pipette as shown in Figure 8.6a. The tip of the electrode is made slightly smaller in internal diameter than the diameter of the axon or nerve bundle being studied. The electrode assembly is filled with isotonic solution and suction applied to the nerve end until the desired... 

In general, it is necessary to use miniature apparatus. Many of the operations ordinarily requiring a separatory funnel can be carried out efficiently (see Fig. 3), by means of the suction pipette. 

Add three cc. portions of acetyl chloride to (a) 1 cc. of ethyl alcohol and (6) to 1 g. of phenol. After one minute pour the mixtures separately into 5 c.c. of water (Caution ). With the suction pipette, separate the reaction product from (6) and test its solubilitj in dilute NaOH to detennine whether the product is still acidic. 

IV. Solubility Behavior.—The solubility tests differ from those applied to individual compounds in one essential point it is necessary to determine whether any part of tlie mixture has dissolved. This is done by separating the solvent and examining it for dissolved material by precipitation, extraction, or distfllation methods, or by combinations of such methods. Diminution of volume in liquid unknowns is occasionally of value. The following scheme is of value in connection with the application of solubility tests on a water-insoluhle mixture. A one-gram sample will usually serve for these tests and the suction pipette, page 112, will be found of particular value in connection with the separations and extractions. All fractions are to be retained for later use. 

Saug-luft, /. vacuum, suction inlet air. -luft-anlage, /. vacuum equipment or plant, -liifter, m. exhauster, -luftkessel, m. vacuum vessel, -maschine, /. exhauster aspirator, -messer, m. vacuometer. -nkpfchen, n. suction cup. -papier, n. absorbent paper, -pipette, /. suction pipet(te). -pumpe, /. suction pump, -raum, m. suction chamber, -rohr, n., -rohre,/. suction tube or pipe, sucking pip siphon Venturi tube, -rdhrehen,... 

To use such pipettes, a suitable pipette filler is first attached to the upper or suction tube. These devices are obtainable in various forms, a simple version consisting of a rubber or plastic bulb fitted with glass ball valves which can be operated between finger and thumb these control the entry and expulsion of air from the bulb and thus the flow of liquid into and out of the pipette. Suction by mouth must never be used to fill a pipette with liquid chemicals or with a solution containing chemicals. 

Recently, we have developed a new version of this system, and this is shown in Figure 36. In this system, instead of the capillary being used as a blow-out pipette, the capillaries are used as wash-out pipettes. The capillaries are dispensed in a block, and the solution flows through the capillaries sequentially as they are presented to 2 press plates which apply pressure to the side of the block and maintain contact at all time. This done with 0-rings and has an effect similar to a suction cup sliding along the block. In Figure 36, it shows how 3 capillaries can be simultaneously emptied into three different channels of an autoanalyzer so that three determinations can be done simultaneously. 

Obtain a clean 25 mL pipette and a suction bulb. Rinse tbe pipette witb 5 mL to 10 mL of CH3COOH, and discard tbe rinse witb plenty of water. Pipette 25.00 mL of CH3COOH into an Erlenmeyer flask. Add two or three drops of pbenolpbtbalein indicator. 

Place the pipette tip in a beaker of distilled water. Squeeze the suction bulb. Maintain your grip while placing it over the stem of the pipette. Do not insert the stem into the bulb. (If your suction bulbs have valves, your teacher will show you how to use them.)... 

Never use your mouth instead of a suction bulb to draw a liquid into a pipette. The liquid could be corrosive or poisonous. As well, you would contaminate the glass stem. 

A patch-clamp (recording) pipette is attached to an individual cell and a gigaohm seal is formed between the cell and the patch-clamp pipette by applying suction through the pipette. 

Avoidance or ban of unsafe techniques in the laboratory, e.g., oral suction of chemicals in pipettes, sucking of halogenated compounds with a water-jet pump because of effluent contamination. 

By means of a graduated pipette provided with a rubber suction bulb, transfer 2ml of MG to a La Motte Co comparator tube and add neutral water to the mark on (he tube. After this, add 0.5ml of La Motte Co bromthymol indicator, close the comparator tube with a clean cork stopper and shake... 

PIPETTE. A slender glass tube open at both ends and having an expanded area at or near the center designed to contain a specific volume of liquid, e.g., 5 ml. Liquid is drawn into the tube by oral or, for the sake of safety, some other form of suction. 

If the volume of liquids is small, separation can be effected by the use of a small pipette, to which is attached a length of rubber tubing the rubber tubing is held in the mouth, gentle suction is applied, and the eye kept on a level with the common surface of the liquids. 

Measure the aliquot portion of the organometallic reagent with a pipette which has been previously warmed in the oven and allowed to cool with a stream of nitrogen flowing through it. The use of a suction bulb is essential. 

Figure 1 Diagram of the micropipette aspiration technique (modified from Lim et al., 2006). L is the length of extension into the pipette, Rc the inner radius of the pipette and AP the suction pressure.

Do not use mouth suction to pipette chemicals or to start as siphon a pipette bulb or an aspirator should be used. 

The distribution of flow about a circular opening under suction has been investigated by the author (1939) and the flow pattern is as shown in Figure 129. The various contours are expressed as percentages of the velocity at the tip. Furthermore, when the coordinates are expressed in terms of the tip diameter, the contours for all openings are identical and their absolute values are functions of the velocity at the opening. Thus, what is important to consider is the ratio Q/A At, where A is the area of the pipette opening. Let us assume for the sake of a concrete example that Q = 10 cu cm, A = 0.01 sq cm, and At = 2 sec. Then the flow at the pipette tip is 500 cu cm per sec. It may be shown that this volume is confined within the 0.5 percent velocity contour. This conforms with a velocity contour surface of 0.005 X 500 = 2.5 cm per sec. Hence all particles... 

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