Volumetric transfer pipette

There are three types of volumetric pipettes volumetric transfer, measuring, and serological. The differences are based on whether the volume within the pipette is subdivided and if the volume in the tip is included in the calibration (see Fig. 2.19). 

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. 

A volumetric transfer pipette (Figure 1-1, A) is calibrated to deliver accurately a fixed volume of a dilute aqueous solution. The reliability of the calibration of the volumetric pipette decreases with a decrease in size, and therefore special micropipettes have been developed. 

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. 

Figure 1-1 Pipettes. A,Volumetric (transfer). B, Ostwald-Folin (transfer). C, Mohr (measuring), D, Serological (graduated to the tip).

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. 

Next add 10 ml of ammonium molybdate reagent with a pipette and transfer the solution to a 100 ml volumetric flask. Rinse the plastic beaker with small volumes of water in this way, remnants of deposited or undissolved... 

Pre-acidified pore water (100 pi, diluted with Millipore Q-water if necessary) was transferred, using an Eppendorf pipette, into a 10 ml volumetric Pyrex flask. To this flask nitric acid (50 pi) was added, and the solution was then brought to volume with Millipore Q-water. Standards were made up by adding various amounts to stock metal solutions (lmg/1), nitric acid (50 pi), and a seawater solution (100 pi) of approximately the same salinity as the samples to be analysed. This final addition ensures that the standards are of approximately the same ionic strength and contain the same salts as the samples. 

Procedure Weigh accurately 0.5 g arsenic trioxide into a beaker, add to it 2 ml of sodium hydroxide solution, and heat to dissolve. Cool and transfer the contents quantitatively to a 100 ml volumetric flask and make up the volume upto the mark with DW. Pipette 20 ml into an iodine-flask, acidify with dilute HC1 carefully and confirm it by adding a little NaHC03 to remove the free excess acid, followed by a further 2 g to get rid of HI formed in the reaction mixture. Now, titrate with 0.1 N iodine solution till the end-point is achieved by the appearance of the first permanent pale straw colour. 

Procedure Weigh accurately about 0.17 g of amoxycillin trihydrate and dissolve in sufficient DW to produce 500 ml. Now, transfer 10 ml of this solution into a 100 ml volumetric flask, add 10 ml of buffer solution pH 9.0 followed by 1 ml of acetic anhydride-dioxan solution, allow to stand for 5 minutes, and add sufficient water to produce 100 ml. Pipette 2 ml of the resulting solution into each of the two stoppered tubes. To tube 1 add 10 ml of imidazole-mercury reagent, mix, stopper the tube and immerse it in a water-bath previously maintained at 60 °C for exactly 25 minutes, with occasional swirling. Remove the tube from the water-bath and cool rapidly to 20 °C (Solution-1). To tube 2 add 10 ml of DW and mix thoroughly (Solution-2). Immediately, measure the extinctions of Solutions 1 and 2 at the maximum at about 325 nm, as detailed above, employing as the blank a mixture of 2 ml of DW and 10 ml of imidazole-mercury reagent for Solution-1 and simply DW for Solution-2. 

Touch the tip of the pipette to the side of the beaker to remove any clinging drop. See Figure F.3. The measured volume inside the pipette is now ready to be transferred to an Erlenmeyer flask or a volumetric flask. 

In an experiment to determine the percentage by mass of manganese in a steel paper clip, it is necessary to prepare various concentrations of standard potassium permanganate solutions. You will learn more about this experiment on p. 88. A standard 0 0010 mol h solution of potassium permanganate is often used as a stock solution in this experiment. Dilutions of the stock solution are prepared by accurately transferring a known volume of the stock solution, using a pipette or a burette, into a volumetric flask (standard flask). The flask is then carefully filled to the graduation mark with deionised water. 

A 2-0 cm volume of 0-0010 mol 1 can be accurately measured using either a 2 cm pipette or a burette and transferred to a 50 cm volumetric flask and made up to the mark with distilled water. 

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. 

Step 4. Transfer the sample by pipette or syringe to a volumetric flask of the volume selected for sample analysis (usually 25-100 mL). Record the amount so transferred (by volume or mass), and compare to volume recorded in shipping papers. Quantitatively rinse the container several times with the same acid solution as that in which the sample was delivered. Transfer the rinse to the volumetric flask that contains the sample. Save the vial in which the sample was shipped (see Step 9). Dilute the sample in the volumetric flask to the mark with the same acid solution. (Note If the sample is to be measured by mass, make the appropriate balance measurements on the volumetric flask when empty, before adding wash and diluting liquid, and when full.) Close the flask, label it, and thoroughly mix the sample by shaking. 

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. 

Take two 100ml aliquot portions and transfer them into two shallow evaporating dishes (of about 300ml capacity) (For transferring the soln either a pipette or a volumetric flask with a short neck, gtaduated to deliver 100ml is used)... 

Since a thiosulfate solution is susceptible to attack by sulfur-metabolizing bacteria, it may be wise to check the standardization of the stock solution with a standard solution of KI03. Place 1.3 to 1.4 g of KIO3 in a weighing bottle, dry it for several hours at 110°C, cool in a desiccator, and weigh it exactly on an analytical balance. Transfer this salt to a clean 100-mL volumetric flask and make up to the mark with distilled water. Rinse a clean 5-mL pipette with several small portions of the iodate solution and then carefully deliver a 5-mL sample into a 250-mL Erlenmeyer flask. Add about 20 mL of distilled water, 5 mL of a 0.5 g/ml KI solution, and 10 mL of 1 MHCl. Titrate at once with the thiosulfate solution until the reddish color turns orange and then yellow and becomes pale. At this point add about 0.5 g of Thyodene indicator, mix well, and titrate until the blue color disappears. 

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. 

Typical volumetric glassware (a) volumetric flask, (h) transfer pipette, (c) measuring pipette,... 

Put the contents of the volumetric flask into one of the clean and dry bottles. Wash the volumetric flask three times with distilled water. By means of the graduated pipette transfer 50 ml of the stock solution into the volumetric flask and dilute to 100 ml. Determine the rotation of this solution at the same temperature as used in the first solution. Dilute 50 ml of the second solution to the same degree, and determine its rotation. Using the formula, calculate the specific rotation for each concentration. Tabulate your observed data and calculations. 

Weigh about 200 mg of vinylpyrrolidone and 2 g of N-(methoxypropyl)-pyrroli-done, accurate to 0.2 mg, into a 100-ml volumetric flask and dissolve in acetone to make 100 ml. Transfer 1.0 ml of the solution to a further 100-ml volumetric flask with a pipette and dilute to 100 ml with acetone (= calibration solution). 

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