Pipet Fillers

Mechanical pipet fillers (sometimes called safety pipet fillers, propipets, or pi-fillers) are more convenient than latex bulbs (Figure 1.4C,D). Equipped with a system of hand-operated valves, these fillers can be used for the complete transfer of a liquid. The use of a safety pipet filler is oudined in Figure 1.5. Never allow any solvent or solution to enter the pipet bulb. To avoid this, two things must be kept in mind (1) always maintain careful control while using valve S to fill the pipet, and (2) never use valve S unless the pipet tip is... 

B Pipet filler courtesy of Curtin Matheson Scientific, Inc. 

C Mechanical pipet filler courtesy of VWR Scientific, Division of Univar. 

How to use a Spectroline safety pipet filler. Courtesy of Spectronics Corporation,West-bury, NY 11590. 

The use of a Mohr pipet is similar to that of a volumetric pipet. Draw the liquid into the pipet with a pipet filler to a level about 2 cm above the 0 mark. Lower the liquid level to the 0 mark. Remove the last drop from the tip by touching it to the inside of the glass container. Transfer the pipet to the receiving container and release the desired amount of solution. The solution should not be allowed to move below the last graduated mark on the pipet. Touch off the last drop. 

Never pipet any solutions by mouth always use a dedicated mechanical pipet filler. Wear gloves, lab coat, and goggles. 

A Latex bulb courtesy of VWR Scientific Division of Umvar B Pipet filler courtesy of Curtin Matheson Scientific, Inc C Mechanical pipet filler courtesy of VWR Scientific, Division of Univar... 

Examine the Spectroline pipet filler and locate the valves marked A, S, and E (Fig. 3.2). These operate by pressing the flat surfaces between the thumb and forefinger. 

Carefully insert the pipet end into the Spectroline pipet filler (Fig. 3.3). The end should insert easily and not be forced. 

Using a Spectroline pipet filler (Fig. 3.3), transfer exactly 10.00 mL of liquid from the graduated cylinder to the beaker. Weigh to the nearest 0.001 g (18), and by subtraction determine the weight of the liquid. Record it on your Report Sheet (19). 

Clamp one clean and dry viscometer on a stand. Pipet 3 mL of your acidified buffer solution into bulb A of your viscometer. Using a suction bulb of a Spectroline pipet filler, raise the level of the liquid in the viscometer above the upper calibration mark. Release the suction by removing the suction bulb and time the efflux time between the two calibration marks. Record this as tG on your Report Sheet (2). Remove all the liquid from your viscometer by pouring the liquid out from the wide arm. Then apply pressure with the suction bulb on the capillary arm of the viscometer and blow out any remaining liquid into the storage bulb (A) pour out this residual liquid. 

Using a 10-mL volumetric pipet and a Spectroline pipet filler, transfer 10.00 mL of the fruit drink into a 125-mL Erlenmeyer flask. Then add 20 mL of distilled water, 5 drops of 3 M HC1 (as a catalyst), and 10 drops of 2% starch solution to the flask. 

Fancier safety pipet fillers such as the one illustrated in FIGURE B.6 may be available for your use in place of a rubber bulb. Safety pipet... 

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