Transfer pipets

Volumetric transfer pipets Measuring and serological pipets ... 

Accuracy tolerances for volumetric transfer pipets are given by ASTM standard E969 and Federal Specification NNN-P-... 

Common types of pipets and syringes (a) transfer pipet (b) measuring pipet (c) digital pipet (d) syringe. 

Voll-mundigkeit, /. (of liquors) body, palate fullness, -pipette, /. a pipet(te) delivering a single definite amount, without a graduated scale transfer pipet. Cf. Messpipette. 

As indicated previously, most pipets are pieces of glassware that are designed to deliver (TD) the indicated volume. Pipets come in a variety of sizes and shapes. The most common is probably the volumetric pipet, or transfer pipet, shown in Figure 4.8. This pipet, like the volumetric flask, has a single calibration... 

TABLE 4.1 Steps Involved in Transferring a Solution with a Volumetric or Transfer Pipet... 

Transfer the organic (top) layer to a small shaker using a transfer pipet. Evaporate the solvent in a steam bath. 

Pipets deliver known volumes of liquid. The transfer pipet in Figure 2-1 la is calibrated to deliver one fixed volume. The last drop does not drain out of the pipet and should not be blown out. The measuring pipet in Figure 2-1 lb is calibrated like a buret. It is used to deliver a variable volume, such as 5.6 mL, by starting delivery at the 1.0-mL mark and terminating at the 6.6-mL mark. The transfer pipet is more accurate, with tolerances listed in Table 2-4. 

Figure 2-11 (a) Transfer pipet and (b) measuring (Mohr) pipet. [Courtesy A. H. Thomas Co., Philadelphia, PA.]... 

Figure 2-10 Proper position of the meniscus—at the center of the ellipse formed by the front and back of the calibration mark when viewed from above or below. Volumetric flasks and transfer pipets are calibrated to this position.

Each instrument that we use has a scale of some sort to measure a quantity such as mass, volume, force, or electric current. Manufacturers usually certify that the indicated quantity lies within a certain tolerance from the true quantity. For example, a Class A transfer pipet is certified to deliver 10.00 0.02 mL when you use it properly. Your individual pipet might always deliver 10.016 0.004 mL in a series of trials. That is, your pipet delivers an average of 0.016 mL more than the indicated volume in repeated trials. Calibration is the process of measuring the actual quantity of mass, volume, force, electric current, and so on, that corresponds to an indicated quantity on the scale of an instrument. 

To calibrate a 25-mL transfer pipet, you should first weigh an empty weighing bottle like the one in Figure 2-17. Then fill the pipet to the mark with distilled water, drain it into the weighing bottle, and cap the bottle to prevent evaporation. Weigh the bottle again to find the mass of water delivered from the pipet. Finally, use Equation 2-3 to convert mass into volume. 

Describe how to deliver 5.00 mL of liquid by using a transfer pipet. 

Which is more accurate, a transfer pipet or a measuring pipet ... 

Acids could be delivered by transfer pipets whose tolerances are given in Table 2-4. So 2 mL means 2.000 0.006 mL... 

Enriched preparations of basophils will form in a band between the two Percoll layers. Carefully remove the upper band using a 1 mL disposable polypropylene transfer pipet. 

Use a pipet puller to prepare glass transfer pipets so that they are 2-3 cm long with a 120-180 pm diameter, and flame polish the end. Fill the pipet with a small amount of light paraffin oil, then an air bubble, then M2, followed by another air bubble. Fill the pipet with 5-7 eggs, followed by another air bubble and a small amount of M2. 

Locate the infundibulum under a dissecting microscope, and create a hole in the bursa with fine forceps. Pick up the infundibulum and insert the transfer pipet into the ampulla. Using a mouth pipet, expel the two bubbles flanking the eggs into the uterus. 

Pipets and burets must be allowed to drain properly in use. Usually, transfer pipets for dilute aqueous solutions should drain for the time specified by the manufacturer before the tip is touched to the wall of the vessel. Buret volumes should not be read immediately upon delivery of the titrant. A suitable length of time should elapse to allow the titrant retained on the walls to drain down. A time interval of 5 to 10 s is usually sufficient. 

Standards of Accuracy The capacity tolerances for volumetric flasks, transfer pipets, and burets are those accepted by the National Institute of Standards and Technology (Class A),1 as indicated in the accompanying tables. Use Class A volumetric apparatus unless otherwise specified in the individual monograph. For plastic volumetric apparatus, the accepted capacity tolerances are Class B.2... 

The capacity tolerances for measuring (i.e., graduated ) pipets of up to and including 10-mL capacity are somewhat larger than those for the corresponding sizes of transfer pipets, namely, 0.01, 0.02, and 0.03 mL for the 2-, 5-, and 10-mL sizes, respectively. 

Oxford Macro Set Transfer Pipetting System 41 Nalgene Pipetting Aid... 

In all steps of the procedure, open and close tubes one at a time, and use a new tip or sterile disposable transfer pipet for each tube. 

Remove supernatant with a sterile disposable transfer pipet, taking care not to disturb the silica pellet. 

Hydroxyethyl functionalities can be anchored to poly(styrene-DVB) by reacting lithiated resin with ethylene oxide (15). A THF suspension of lithiated resin (2 g in 50 ml) was cooled to -80°C, and 15 ml of ethylene oxide at -80°C were added with a transfer pipet. The mixture was brought to room temperature (in about 3 hr) and the beads were separated by filtration, washed successively with THF H20 (3 1), 10% HC1, H2O, THF, and ether, and then vacuum dried at 70°C. The infrared spectrum showed an OH absorption. 

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. 

Pipets permit the transfer of accurately known volumes from one container to another. Common types are shown in Figure 2-17 information concerning their use is given in Table 2-2. A volumetric, or transfer, pipet (Figure 2-17a) delivers a sin-... 

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