A serial dilution is set up with an initial antigen concentration of 250 ug/mL. A serial dilution is carried out where 20 uL is moved from each tube into an adjacent which has been prefilled with 80 uL of buffer. What is the tube concentration of tube 8, again assuming that tube 1 has a concentration of 250 ug/mL?
7 steps from 1 to 8 ... each step is 1/5 as concentrated as the previous one
250 * (1/5)^7
To find the tube concentration of tube 8, we need to understand the process of serial dilution.
Serial dilution involves repeatedly diluting a solution to create a series of lower concentration solutions. In this case, 20 uL of the antigen solution is transferred from each tube to the next, along with 80 uL of buffer solution.
Starting with tube 1, which has an initial antigen concentration of 250 ug/mL, we can calculate the concentration of each tube using the dilution formula:
C1V1 = C2V2
C1 - Initial concentration
V1 - Initial volume
C2 - Final concentration
V2 - Final volume
Let's set up the calculations for each tube:
Tube 1:
C1 = 250 ug/mL
V1 = 100 uL (20 uL from tube 1 + 80 uL buffer)
C2 = ?
V2 = 100 uL
Using the dilution formula:
C1V1 = C2V2
(250 ug/mL)(100 uL) = C2(100 uL)
25000 ug = C2(100 uL)
C2 = 25000 ug / 100 uL
C2 = 250 ug/mL
Tube 2:
C1 = 250 ug/mL
V1 = 100 uL (20 uL from tube 2 + 80 uL buffer)
C2 = ?
V2 = 100 uL
Using the dilution formula:
C1V1 = C2V2
(250 ug/mL)(100 uL) = C2(100 uL)
25000 ug = C2(100 uL)
C2 = 25000 ug / 100 uL
C2 = 250 ug/mL
Similarly, we can calculate the concentration for tubes 3, 4, 5, 6, 7, and finally tube 8:
Tube 3: C2 = 250 ug/mL
Tube 4: C2 = 250 ug/mL
Tube 5: C2 = 250 ug/mL
Tube 6: C2 = 250 ug/mL
Tube 7: C2 = 250 ug/mL
Tube 8: C2 = 250 ug/mL
Therefore, the tube concentration of tube 8, assuming tube 1 has a concentration of 250 ug/mL, is also 250 ug/mL.