Exp0_Sp2010 - 0-1 First Lab Period INTRODUCTION TO THE...

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0 - 1 First Lab Period INTRODUCTION TO THE LABORATORY Each student is to perform the exercises individually in any order. 1. Reproducible pipetting Pipetman™ single sample pipettes Finnpipette® multichannel pipettes 2. Spectrophotometry: Theory and Operation Shimadzu Spectrophotometer (Photometric and Spectrum functions) Microplate Reader (Basic Operations) Nanodrop Spectrophotometer (Basic Operations) 3. Calibrating the pH meter EXERCISE 1: Reproducible Pipetting: gravimetric analysis with Pipetman Pipettors Pipetman Micropipets: Specifications Accuracy: Accuracy means the closeness with which the dispensed volume approximates the volume set on the pipette. Accuracy is specified as "mean error", the maximum amount by which the mean value of a large number of replicate measurements of the same volume will deviate from the set volume. Precision: Precision means the "scatter" of individual measurements around the mean of a large number of replicate measurements of the same volume; how close the values are to one another. Specifications for precision are generally tighter than for accuracy. In most experiments, where sample measurements are compared to standards, the precision specification will determine the accuracy of results as long as both samples and standards are measured by the same individual using the same Pipetman . A. Operation: Practice pipetting with a Pipetman TM 1. Adjust the P-1000 pipetting device to 0.9 ml (= 900 μ l). Always dial down to the desired volume . 2. Attach a disposable tip to the end of the pipette shaft and press on firmly to ensure an airtight seal. 3. Depress the plunger to the FIRST POSITIVE STOP and hold in place. PIPETMAN SPECIFICATIONS Volume Increment Accuracy Precision Model μ l μ l (mean error) (repeatability) Relative % Absolute μ 1 Relative % Absolute μ l 2 5 0.1 2 0.04 P-20 10 0.02 1 0.1 0.5 0.05 20 1 0.2 0.3 0.06 50 1 0.5 0.4 0.2 P-200 100 0.2 0.8 0.8 0.25 0.25 200 0.8 1.6 0.15 0.3 100 3 3 0.6 0.6 P-1000 500 2 0.8 4 0.2 1 1000 0.8 8 0.13 1.3
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0 - 2 4. Holding the pipette vertically , immerse the end of the disposable tip into a beaker of water. With the tip immersed in water, gently release the plunger and allow the pipette tip to fill with liquid. Never let it snap up by just letting go of the plunger/pushbutton. Wait a few seconds to make sure that the full volume of liquid is drawn up into the pipette. Note: be sure air bubbles are not drawn up into the pipette, and check that liquid does not drip from pipette tip. 5. To dispense the sample, place the tip against the wall of a 1.5 ml plastic microcentrifuge tube in a tube rack, then depress the plunger slowly to the FIRST POSITIVE STOP and continue depressing the plunger through to the SECOND FULL STOP position to fully eject the liquid in the pipette tip. Note: placing the pipette tip in contact with the plastic surface of the microcentrifuge tube is
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Exp0_Sp2010 - 0-1 First Lab Period INTRODUCTION TO THE...

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