Pipettes graduated

Dissolve 10 g. of sym.-tribromoaniline (Section IV,47) in 60 ml. of rectified spirit and 15 ml. of benzene in a 200 ml. bolt-head flask by heat ing on a water bath. Add, from a burette or small graduated pipette, 5-3 g. (3-5 ml.) of concentrated sulphuric acid to the hot solution and gently swirl the liquid. Attach a reflux condenser to the flask and heat on a water bath until the clear solution boils. Detach the condenser, remove the flask from the water bath, and add 3 5 g. of powdered sodium... 

Amount of material required. It is convenient to employ an arbitrary ratio of 0 10 g. of solid or 0 20 ml. of liquid for 3 0 ml. of solvent. Weigh out 0 10 g. of the finely-powdered solid to the nearest 0 01 g. after some experience, subsequent tests with the same compound may be estimated by eye. Measure out 0-20 ml. of the liquid either with a calibrated dropper (Fig. 11,27, 1) or a small graduated pipette. Use either a calibrated dropper or a graduated pipette to deliver 3 0 ml. of solvent. Rinse the delivery pipette with alcohol, followed by ether each time that it is used. 

Graduated pipettes consist of straight, fairly narrow tubes with no central bulb, and are also constructed to a standard specification [BS 6696 (1986)] ... 

Using a graduated pipette, add 4 mL of the stock INP mixture prepared in Part A to the test tube marked INP. 

Cut a plastic graduated pipette into a piece that is 5-cm long. Similarly, cut a piece of surgical rubber tubing 4-cm long. 

Thread a length of copper wire through a piece of the graduated pipette. Wrap an end of the copper wire around the end of one of the platinum or graphite electrodes, as shown in Figure A, step 1. 

Graduated Pipettes They have graduated stems and are used to deliver different small volumes as needed. However, they are not normally used for measuring very exact volumes of liquids. 

Use a safety pipette filler to draw 10 mL of 6.0M hydrochloric acid (HC1) into a 10-mL graduated pipette. 

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... 

Pipettes are used for the exact measurement of a definite volume of a liquid. They are narrow cylindrical glass tubes with still narrower top and bottom ends (Fig. 4a). The upper part of an ungraduated pipette has a mark showing up to what level it must be filled to obtain the volume indicated on it. Pipettes with a volume of 10 or 20 ml are used the most. Graduated pipettes are also used (Fig. 45). 

The plates are then removed from the cell and the latter, carefully taken from the thermostat o-i c c. of N/io-caustic potash solution is then added from a graduated pipette, the end of which touches the wall of the cell as near as possible to the surface of the liquid. The latter is mixed—care being taken that no bubbles remain adhering to the electrodes—and the cell again placed in the thermostat and a second reading taken at the same temperature as the first. Successive readings are made in the same way after addition of successive tenths of a c c. of the N/io-alkali. 

Put the lid in place and switch on the apparatus. Carefully add 0.1 N sodium hydroxide with stirring to adjust to pH 9.2. Using a rapid-flow graduated pipette, transfer about 05 mL of the previously homogenized reference suspension, start the chronometer, and add continuously 0.1 N sodium hydroxide to maintain the pH at 9.0. After exactly 1 min, note the volume of 0.1 N sodium hydroxide used. Carry out the measurement a further four limes. Discoid the first reading and determine the average of the four others (Si). Make two further determinations (S2 and Sa). Calculate ihe average of the values, Si, Si, and S3. 

Remove the septum and introduce rapidly 0.35 mL of trifluoroacetic acid with a graduated pipette. 

Dilute the solution with 15.0 mL of distilled water from a graduated pipette. Cover tightly and shake the tube to ensme thorough mixing. 

Two 2-mL graduated pipettes, used for dispensing nonstandard amounts of sucrose and enzyme solntion... 

One 1-mL graduated pipette, used for dispensing buffer solution and distilled water... 

Two 1-mL transfer pipettes one 2-mL transfer pipette one 5-mL transfer pipette one 1-mL graduated pipette two 2-mL graduated pipettes one 25-mL graduated cylinder or pipette pipetting bulb glass-stoppered flask volumetric flasks, beakers, test tubes. 

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