User:Pauline Wonnenberg/Notebook/CHEM 471 Fall 2017/2017/08/29

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Objectives Prepare Stock Solutions Prepare AuNPs Practice Measurements Description Preparation of Stock Solutions: HAuCl4 Preparation: Goal 1: 2.5mM HAuCl4 into 50mL flask Calculations: 0.05L x 2.5x10-3M = 1.25x10-5moles HAuCl4 = 339.785g/mol 339.785g/mol : 1.25x10-5moles = 0.004247g = 4.247mg BSA Preparation: Goal 2: 250μM BSA into 50mL flask Calculations: 250x10-6M x 0.05L = 1.25x10-5moles BSA molar mass is 66000g/mol therefore, 66000g/mol x 1.25x10-5moles = 0.825 grams of BSA The preparation for both these stock solutions were finished by adding distilled water up to the mark on their respective volumetric flasks. Preparation of AuNP Solutions: Test Tube 1 (1:80 ratio) Preparation: Calculations: 1mL HAuCl4 x 2.5mM HAuCl4 x (1m mol BSA / 80 m mol HAuCl4) x (1 / 250μM BSA) (μ / 10-3) = 0.125mL 1mL of HAuCl4 + 0.125mL BSA + 8.875mL HAuCl4 Test Tube 2 (1:160 ratio) Preparation: Calculations: 0.125mL / 2 = 0.0625mL 1mL of HAuCl4 + 0.0625mL BSA + 8.9375mL HAuCl4 Measurement Practice: Prepare 100mL of 1.71mM NaCl from solid 0.1L x 1.71x10-3M NaCl = 1.71x10-4moles of NaCl mass of NACl = 1.71x10-4 x 58.44g/moles = 9.99mg Prepare 10mL of 13.5μM dye of stock and wet flask; dye concentration=161mM 0.01L x 13.5x10-6M dye = 1.35x10-7moles dye M1V1=M2V2 13.5x103mMx20mL = 161mMxV2 V2=8.385x10-7L=0.8385μL Data AuNP Solutions: The test tube on the left represents the 1:80 Au:BSA ratio. The test tube on the right represents the 1:160 Au:BSA ratio. With this ratio, AuNP fibers should have formed. As it did not, we concluded that the ratio present in the test tube (on the right side of the picture) is lower than 1:160. Measurement Practice: By using a scale and a beaker. We measured the accuracy of a 2mL pipet finding that the average amount of liquid transported, when set at 2mL, is under the set amount. There is a 1.7% error in precision using this specific pipet. Reagent Purities Is that glassware really clean? Using the US spectrometer, the highest absorbance point for the distilled water analysis was found at about 350nm. Then using the fluorometer, mulitple peaks appeared with the highest peak at around 450nm. Is DI water pure? We tested three different types of water and their conductivity: DI water: 2.37 μS/cm Tap Water: 386 μS/cm HPLC: 3.42 μS/cm The lower μS/cm, the more pure the water is.