Dilutions/Titers: 25. Calculate the dilution factor for the following problem: 1

Question

Dilutions/Titers: 25. Calculate the dilution factor for the following problem: 1 0 mL sample added to 190 ml diluents Ce 99 26. What is the final dilution of an unknown blood specimen using 0.1 mL blood with 3.4 ml of water and 1.5 mL of reagents? 27. If 20 mL of saline is added to 4 mL of serum, what is the serum dilution? 28. A urine sample has a concentration of 500 mg/dL. A dilution series is then carried out with the following dilutions for each tube: ½, ½, ½, ½ and ½. a. Find the concentration in each test tube. b. Give the final concentration for the sample

Explanation / Answer

25) The dilution factor is the initial volume divided by the final volume

DF=Vi/Vf

Vi = 10 mL

Vf = 10 mL + 190 mL = 200 mL

DF = 10mL/200mL = 1/20

This is a 1:20 dilution.

The dilution factor is 20

26)

Vi = 0.1 mL

Vf = volume of blood sample + volume of water

    = 0.1ml + 3.4 ml = 3.5 ml

DF = 0.1mL/3.5mL = 1/35

This is 1:35 dilution

Dilution of unknown blood sample is1:35dilution.

Refrigerant does not involve in process of dilution

27)

Vi = 4 mL

Vf= serum volume + saline volume

    = (4 + 20) mL= 24 mL

DF =Vf/Vi

    = 4ml/ 24ml = 1/6

Serum dilution is 1:6 dilutions

28) a.

Concentration in 1st test-tube = 500 mg/dL x 1/2 = 500 mg/dL/2 = 250 mg/dL

Concentration in 2nd test-tube = 250 mg/dL x 1/2 = 250/2 =125 mg/dL

Concentration in 3rd test-tube = 125 mg/dL x 62.5 mg/dL

Concentration in 4th test-tube = 62.5 mg/dL x 1/2 = 62.5/2 = 31.25 mg/dL

b.

The dilution factor after four dilutions is ½ x ½ x ½ x ½ = 1/16

The concentration of the original urine sample was 500 mg/dL,

The concentration of final sample   = 500 mg/dL x 1/16 = 31.25 mg/dL

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