Serology Calculations Immunology Review 415
- How would you prepare a 5% suspension of human group O RBCs?
5% = 5 mL per 100 mL
Mix 5 mL of packed RBCs + 95 mL of buffer, or for a smaller amount, 0.5 mL of packed RBCs + 9.5 mL buffer. Any 1:20 dilution could be used.
(5:100 = 1:20)
- How would you prepare 5 mL of a 1:10 dilution of serum?
1 x
10
=
5
10 x = 5
x= 0.5 mL
0.5 mL diluted to 5 mL is a 1:10 dilution, so mix 0.5 mL of serum + 4.5 mL of buffer.
- How would you prepare 10 mL of a 1:100 dilution from a 1:10 dilution?
A. Determine the dilution factor to make a 1:100 dilution from a 1:10 dilution:
1/10 × 1/x= 1/100
1/10x= 1/100
10 x= 100
x= 10
A 1:10 dilution of a 1:10 dilution yields a 1:100 dilution. (1/10 × 1/10 = 1/100).
B. Determine how to make 10 mL of a 1:10 dilution:
1:10 dilution is 1 part + 9 parts. To make 10 mL, mix 1 mL of solution + 9 mL of buffer.
To make 10 mL of a 1:100 dilution from a 1:10 dilution, mix 1 mL of the 1:10 dilution + 9 mL of buffer.
- What is the dilution in tube 4 of a twofold serial dilution, if tube 1 is undiluted?
1 ×^1 / 2 ×^1 / 2 ×^1 / 2 =^1 / 8
