Glass volumetric pipettes

Draw up the desired volume into the pipette and transfer this to a suitable volumetric flask. Dilute to volume with solvent and invert to mix. Further dilutions can be performed in the same manner. 

You have been asked to dilute a drug solution 10 times, using mobile phase as the solvent. You have a starting volume of 50 mL (solution A). Using a 5 mL volumetric pipette, draw up 5 mL of solution A and dispense this into a 50 mL volumetric 

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Fig. 3.2 Glass pipettes (a) graduated pipette, reading from zero to shoulder (b) graduated pipette, reading from maximum to tip, by gravity (c) bulb (volumetric) pipette, showing volume on bulb.

Accuracy tolerances for volumetric transfer pipettes are given by ASTM Standard E969.02 Standard Specification for Glass Volumetric (Transfer) Pipets, West Conshohodcen, PA American Society for Testing of Material, 2003 and Federal Specification NNN-P-395. 

Transfer 100 ml of the sample water to a 250 ml conical flask with a volumetric glass. Add two drops of bromocresol green indicator with a disposable Pasteur-pipette. 

The term to deliver is based on the concept that when you pour a liquid out of a glass container, some of that liquid will remain on the walls of that container. Because not all of the measured liquid is completely transferred, the material left behind should not be considered part of the delivered sample. Pipettes have two different types of to deliver One which requires you to blow out the remaining liquid, and one that does not. Some volumetric containers are made out of plastic which does not wet like glass. Because these containers drain completely, the to contain is the same as the to deliver. Because some materials (i.e., mercury) do not wet the walls of any container, they should be used with only to contain measuring devices. 

Fill a 500-mL volumetric flask with solution A, the temperature of which should be within a few tenths of a degree of 25.0°C. (Adjust the temperature by swirling under ranning hot or cold water before the flask has been entirely filled, then make up to the mark.) Pour the solution into the clean and reasonably dry calorimeter and allow the flask to drain for a minute. Work a plug of stopcock grease into the capillary hole in the bottom of the inner vessel. The glass must be absolutely dry, or the grease will not stick. Pipette in 50 mL of solution B. Place the inner vessel in the calorimeter carefully. 

Three 200-mL beakers (bottom painted white) two 250-mL and one lOO-mL beakers two 5-, one 20-, two 25-, and one 50-mL pipettes pipetting bulb one 250- and one 500-mL volumetric flask four 250-mL Erlenmeyer flasks with four corks to fit one 10-mL graduated cylinder glass-marking pencil stopwatch or timer. 

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. 

Ostwald viscosimeter two 100- and two 250-mL volumetric flasks a 10- and a 50-mL pipette pipetting bulb 250-mL glass-stoppered flask one 100- and two 250-mL beakers stirring rod hot plate thermometer stopwatch or timer length of gum-rubber tubing. If polymer stock solution is to be prepared by the student weighing bottle funnel Pyrex wool. 

Modem Erlenmeyer flasks and beakers have approximate volume calibrations fused into the glass, but these are very approximate. Somewhat more accurate volumetric measurements are made in the 10-mL graduated cylinders. For volumes less than about 4 mL, use a graduated pipette. Never apply suction to a pipette by mouth. The pipette can be fitted with a small rubber bulb. A Pasteur pipette can be converted into a calibrated pipette with the addition of a plastic syringe body [see Fig. 11(d)] or you can calibrate it at 0.5, 1.0, and 1.5 ml and put three file scratches on the tube this eliminates the need to use a syringe with this Pasteur pipette in the future. Also see the Pasteur pipette calibration marks in the back of this book. You should find among your equipment a 1-mL pipette, calibrated in hundredths of a milliliter [Fig. 11(a)]. Determine whether it is designed to... 

To use a volumetric solution it is poured into the burette, whose stopcock has been closed, until above the o mark the stopcock is then slightly opened so as to expel all air from the delivery tube. Tne float (Fig. 61) is now introduced from above, and touched with a glass rotl to free it from adhering air-bubbles and the solution allowed to flow out from below until the mark on the float is opposite the o of the burette All is now ready for use a given quantity of the solution to be analyzed is measured into a pipette and placeil in a beaker, a few drops of the imli-cator solution are added, and the standard sohiuon allowed to flow in until the end reaction is reached. The reading of the burette is then taken and the calculation made. 

Using a clean and dry glass pipette (volumetric), transfer 1.0 mL of the 5000-ppm BTEX to a 10-mL volumetric flask which has been previously half-filled with the most suitable solvent that you chose earlier. Adjust to the calibration mark with this solvent and label as, for example, 500 ppm BTEX. This is what EPA methods call a primary dilution standard because it is the first dilution that the analyst prepares from a given source which has a higher concentration. 

Dissolve approximately 0.01 g of sodium lauryl sulfate in between 50 and 10 mL of MeOH in a 50-mL beaker. Transfer the contents of the beaker to a 10-mL volumetric flask and adjust to the mark with MeOH. This yields a stock solution whose concentration is 1000 ppm. Transfer 1 mL using a glass pipette and pipette pump to a 10-mL volumetric flask. Adjust to the mark with DDL This yields a primary dilution reference standard whose concentration is 100 ppm. 

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