LAB 02: Measuring And Dispensing Liquids

LAB 02: Measuring and Dispensing Liquids
Introduction
Pipetting is one of the most important and basic skills when it comes to experimental science. Good pipetting skills allow an individual to put trust in his or her results, prevent waste of materials, and assure reproducibility of results. In order to correctly pipette liquids, the volume range must be first determined. p1000 micropipettes have a volume range of 200 - 1000 uL, p200 micropipettes have a volume range of 20 - 200 uL, and p20 micropipettes have a volume range of 0.5 - 20 uL. A dial is used to adjust volume within each given range. A clean tip is applied before pressing the plunger to the first (soft) stop. Still holding the plunger to the first stop, the tip is inserted into
Each of the tubes were weighed and their masses were recorded. A p200 micropipette was set to 200 uL and was attached to a clean pipette tip at its end. Two hundred microliters of water was drawn and transferred into the tube labelled “p200”. Another 200 uL was drawn and transferred into the tube labelled “p200”. The p200 micropipette was set to 100 uL and 100 uL was drawn and transferred into the tube labelled “p200” for a total of 500 uL of water in that tube. A p1000 micropipette was set to 500 uL and was attached to a clean pipette tip at its end. Five hundred microliters of water was drawn and transferred into the tube labelled “p1000”. To transfer 500 uL of water into the “TP” tube, the bulb of a graduated transfer pipette was squeezed. Then, the pipette was lowered into the water, and the bulb was gently released until the water’s meniscus touched the 0.5 mL mark. Without releasing the bulb, the transfer pipette was lifted out of the water, and the the bulb was pressed to deliver 500 uL of water into the “TP” tube. Each of the microcentrifuge tubes were were weighed and their new masses were
For the blank, 1 mL of water was pipetted using a p1000 to a cuvette, which was placed into the spectrophotometer. The absorbance value was recorded at 590 nm. One hundred twenty five microliters of bromophenol blue and 2875 uL of deionized water (for a solution of 4.167% bromophenol blue) were added to a test tube and were mixed using a vortex. After cleaning the cuvette, 1 mL of solution was pipetted out using a p1000 into the cuvette, which was placed into the spectrophotometer. The absorbance value was recorded at 590 nm. In the same original test tube, 1 mL of deionized water was added (for a solution of 2.777% bromophenol blue) and the solution was mixed using a vortex. After cleaning the cuvette, 1 mL of solution was pipetted out using a p1000 into the cuvette, which was placed into the spectrophotometer. The absorbance value was recorded at 590 nm. In the same original test tube, 1 mL of deionized water was added (for a solution of 1.853% bromophenol blue) and the solution was mixed using a vortex. After cleaning the cuvette, 1 mL of solution was pipetted out using a p1000 into the cuvette, which was placed into the spectrophotometer. The absorbance value was recorded at 590 nm. In the same original test tube, 1 mL of deionized water was added (for a solution of 1.233% bromophenol blue) and the solution was mixed using a vortex. After cleaning the cuvette, 1 mL of solution was pipetted out using a