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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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