4. Using the P1000, 100, 200 and 400 l of the 0.01% XC stock solution was measured into the bottom of three more eppendorf tubes. Water was added to bring the final volume to 1ml.
5. Each eppendorf tube was covered and inverted several times to thoroughly mix the contents. 6. Each dilution was visually compared to the reference ones. 7. The absorbance of the dilutions were recorded in the spectrophotometer in the Chemistry Lab. Station 2: Introduction to Our Spectrophotometers Part 1: Using the Specord 210 1. Using the P1000, 1ml of water was measured into a plastic cuvette. This cuvette was used as the blank in the spectrophotometer. 2. The machine was set to read absorbances at 600nm and the visible light was on. 3. The blank was placed into the spectrophotometer at position 1, which is the furthest back in the instrument. It was ensured that the flat window of the cuvette and not the indented sides were in the light beam that ravels from left to right. 4. The spectrophotometer door was closed. “Blank” was clicked on the lower left screen after which a “reading blank” message appeared. After the message was gone, the blank was set. 5. The blank was replaced with the first sample. The door of the spectrophotometer was closed and “read samples” was clicked. The value was recorded. 6. All 12 samples were measured. 7. The “clear” button was clicked and “save data was unchecked” to erase the data. 8. Steps 1-7 were repeated for another set of 12 samples. Station 3: Introduction to Our Microscopes Station 4: Introduction to pH 1. The pH of the given solutions was measured. 2. The pH electrode was removed from the storage solution and rinsed over the waste beaker using distilled water from the wash bottle. A Kimwipe was used to gently dry the electrode. 3. The mechanical arm that holds the electrode was manipulated to place the electrode ½ way into the 15ml conical tube with the calibration buffer pH 7.0. The red measurement tip was submerged. The “measure” button in the upper right corner of the pH meter’s control panel was pressed. After the reading had stabilized (“AR” light stopped flashing) it was determined to be a pH of 7. 4. The electrode was rinsed and dried then placed in the sorbitol solution. The mechanical arm was used to hold the electrode at the edge of the beaker. The pH of the solution was then read and one of the teaching faculty was notified of the value obtained.
- Summer '15