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Calculations II. Working With Molarity (M). In Some Cases Molarity (M) Is Known. Ex. 10 -5 M Compound X (MW 325) You Also Know That Cultures Should Be “fed” 30 ng/mL Of Compound X What Volume Of Compound X Stock Solution Should You Use To “feed” 10 mL Of Culture?. Working With Molarity (M).
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Working With Molarity (M) • In Some Cases Molarity (M) Is Known. • Ex. 10-5 M Compound X (MW 325) • You Also Know That Cultures Should Be “fed” 30 ng/mL Of Compound X • What Volume Of Compound X Stock Solution Should You Use To “feed” 10 mL Of Culture?
Working With Molarity (M) One Approach Is To Convert 30 ng/mL of cpd X Into Molarity
Working With Molarity (M) • Alternative Approach
Exercise • Compound Y: 3x10-5 M, (MW 425), “Feed” 5 mL Culture with 10 ng/mL • Ans: 3.9 L
When High Accuracy Is Needed • If volume added is significant Ex. 1 mL, and Culture Volume is 10 mL • First determine V1 Based On Culture Volume (V2=10 mL) • Re-determine V1 Based on New Culture Volume (10mL+V1+0.5mL extra)
Exercise • Determine what volume to use from stock vial • Culture volume is 11 ml • Stock vial concentration is 1mM • “Feeding” concentration is 0.1 mM • Final Culture Volume Should Be Between 12.25-12.5 mL
Cell Calculations • Cell Suspension of 2 mL @ 5x106 cells/mL • Use a 24 well plate, Prepare 12 wells @ 0.25x106 cells/mL, 1 mL in each well • Add 50 L To Each Well • Add 950 L Medium
Cell Calculations • Cell Suspension of 10 mL @ 0.25x106 cells/mL • Use a 25cm2 flask, Prepare 5 mL @ 1x106 cells/mL • You will have to resuspend cells in smaller volume • Even then, not enough cells for 5 mL @ 1x106 cells/mL • Enough for 2.5 mL @ 1x106 cells/mL
Exercises • Prepare 12 wells @ 0.25x106 cells/mL • Well volume: 0.5 mL • Cell Suspension concentration: 10x106 cells/mL, 2 mL • Answer: 13 L+487 L • How Many wells can you prepare? • Answer: (20x106/0.125x106) =160 wells