In: Biology
You are given 5mL of 3mg/mL protein solution. You are asked to prepare samples for SDS-PAGE containing 250ng, 500ng, 750ng, and 1000ng. Your pipettes are calibrated to 2uL at the lower limit. Your total volume is 20uL, with 5uL being your loading buffer. How would you prepare these samples?
To make these solutions first dilute the given stock.
Given: 3mg in 1ml it means 3000ug in 1000ul
.so make a solution of 66.7ug per ml that can be used as stock. 3000ug = 1000ul so 66.7 ug =? So 3000× x÷66.7×1000
Ans is 22.23 ul.
Take 22.23 ul of given original stock and add remaining dilution buffer or water to make volume 1ml. So it's concentration will be 66.7ug/ml.
I.e 22.23ul stock + 977.77ul of diluent.=1ml of 66.7ug of stock to be used in further making of solutions.
66700ng= 1000ul so 250ng=? Ul ans is 3.7 ul.so take 3.7 ul of stock and add 11.3 ml of diluent to make volume of 15 ul .
15ul sample +5ul loading buffer= 20 ul of 250ng sample.
Similarly for 500 ng = 7.4 ul stock + 7.6ul of diluent +5ul of loading buffer
For 750ng = 11.2ul stock+ 3.8ul diluent +5 ul of loading buffer= 20 ul sample of 750ng
For 1000ng = 15ul stock+5 ul of loading buffer = 20 ul sample of 1000ng concentration.
*conversions used
1mg = 1000ug
1ug= 1000 ng
1ml =1000ul