Pipets types

Analytical chemists use a variety of glassware to measure volume, several examples of which are shown in Figure 2.4. The type of glassware used depends on how exact the volume needs to be. Beakers, dropping pipets, and graduated cylinders are used to measure volumes approximately, typically with errors of several percent. 

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

I. 000 X 10- 1.000 X 10-k 1.000 X 10-k and 1.000 X 10- M from a 0.1000 M stock solution. Calculate the uncertainty for each solution using a propagation of uncertainty, and compare to the uncertainty if each solution was prepared by a single dilution of the stock solution. Tolerances for different types of volumetric glassware and digital pipets are found in Tables 4.2 and 4.4. Assume that the uncertainty in the molarity of the stock solution is 0.0002. 

Figure 6, Self zeroing ultramicro pipets. Ay constriction at two marks By overflow type with constriction at both ends C, Lang-Levy pipet D, another type of constriction pipet Ey Speedipet of Natelson,...

Other apparatus includes a Waring Blendor, 1-quart mixing cup 24 or more 125-ml. Erlenmeyer flasks two 10-ml. graduated cylinders a 50-ml. glass-stoppered volumetric flask and 10-ml. volumetric and 5-ml. serological-type pipets. 

Br > Cl > I. This conductance was not time-dependent. On the other hand, Cl conductance stimulated by the Ca2+ ionophore A23187 (2.5 pM) or elevation in the free Ca2+ levels in the pipet from 100 to 500 nM was time-dependent and exhibited a nonlinear current-voltage relationship that was outwardly rectifying. The permselectivity of this Ca2+-stimulated conductance was 1 > Br > cr, distinguishing it from the cAMP-stimulated Cfr conductance. As both calcium ionophore A23187 and cAMP were shown to elevate the Cl conductance of the cornea, it is quite likely that these two types of Cr channels are present in the corneal epithelium [96,106,114],... 

The three volumetric glassware products we will discuss are the volumetric flask, the pipet, and the buret. Let us study the characteristics of each type individually. 

Indicate which type of measurement scale (nominal, ordinal, interval, or ratio) is usually used for the following characteristics time, mass, library holdings, gender, type of heart attack, cholesterol level as measured by a clinical chemical laboratory, cholesterol level as reported by a doctor to a patient, pipet volume, and leaves on a plant. 

Materials. Gelman 37 mm, type A/E glass fiber, GN-4 0.8 metricel, and DM-800 0.8 membrane filters were used in this study. Spectral quality, pyrolytic coated, graphite furnaces and rods were used in the study. The furnace capacity was 5 yL of solution. Manual sample injections were made with a 5 yL Eppen-dorf pipet 4700 using disposable tips. 

Fixed volumes of original solution and of collapsed foams were taken with a micro (overflow type) pipet and transferred to respective sample plates which were coated partly with silicone oil to prevent wetting. The solution was dried gradually with infrared ray lamp and then radioactive counts were determined. On the other hand, the concentration of the solution of collapsed bubbles was determined by weighing. The accuracy of this method was confirmed by drying the solution of known concentration at respective experiments. The loss of acetic acid... 

Practical biochemistry is highly reliant on analytical methods. Many analytical techniques must be mastered, but few are as important as the quantitative transfer of solutions. Some type of pipet will almost always be used in liquid transfer. Since students may not be familiar with the many types of pipets and the proper techniques in pipetting, this instruction is included here. 

Fractional volumes of liquid are transferred with graduated pipets, which are available in two types—Mohr and serological. Mohr pipets (Figure 1.4G) are available in long- or short-tip styles. Long-tip pipets are especially attractive for transfer to and from vessels with small openings. Virtually all Mohr pipets are TD and are available in many sizes (0.1 to 10.0 mL). The marked subdivisions are usually 0.01 or 0.1 mL, and the markings end a few centimeters from the tip. Selection of the proper size of pipet is especially important. For instance, do not try to transfer 0.2 mL with a 5 or 10 mL pipet. Use the smallest pipet that is practical. 

---