Question

Lab 5: Additional Dilution Problems You have a stock solution that contains 24 mg/ml of protein. You want to make a set of standards with the following concentrations: 12 mg/ml, 6 mg/ml, 3 mg/ml and 1.5 mg/ml You need a minimum of 500 ul of each standard after all dilutions are completed. Using the technique of serial dilution, explain how you would make your standards by filling in the chart below. Std 4 Std 1 12 Std 2 6 Std 3 3 concentration (mg/ml) dilution factor/ from? volume of concentrate volume of diluent final dilution of stock final volume/tube You have a stock solution that contains 2 mg/ml of protein. You want to make a set of standards with the following concentrations: 150 ug/ml, 50 ug/ml, 16.67 ug/ml, and 5.56 pg/ml. You need a minimum of 300 ul of each standard. Using the technique of serial dilution, explain how you would make your standards by filling in the chart below. Std 1 Std 2 Std 3 Std 4 concentration dilution factor / from? volume of concentrate volume of diluent final dilution of stock final volume/tube

Answer 1

	Std 1	Std 2	Std 3	Std 4	Std 5
Concentration	12	6	3	1.5	0.75
Dilution factor/from?	2 from stock	2 from Std1	2 from Std 2	2 from Std 3	2 from Std4
Volume of concentrate	500uL	500uL	500uL	500uL	500uL
volume of diluent	500uL	500uL	500uL	500uL	500uL
final dilution of stock	12	6	3	1.5	0.75
final volume/tube	1000uL	1000uL	1000uL	1000uL	1000uL

1. First of all the tubes namely Std 1,2,3,4,5 will filled by 500uL Diluent (eg Water)

2. Then for getting concentration of 12mg/mL in Std 1 tube, 500uL of from stock solution is pipetted in tube Std 1.

3. Repeat the same step 2 (i.e. transfer 500uL in adjacent tube) for each tube till Std 5 tube. Std 5 can be discarded as dilution upto Std 4 is required.

Dilution factor = total volume of solution per aliquot volume.

Where total volume of solution is: 500uL + 500uL = 1000 uL

i.e. 1000uL/500uL= 2

Stock 500 ml To ue 5oolll 500ML 50ML 5coul del 24 mg/ml 6 mg/ml 3 mg/ml Total Vol. = loool1 Vol of Diluent 500 u 500ML 500 ML 500 ML 500ML can be discarded Dilution_ Factor - = 500+500 500 100o = 2 500

Answer2- Stock Solution=2mg/mL= 2000ug/mL

	Std 1	Std 2	Std 3	Std 4
Concentration	150 ug/mL	50 ug/mL	16.67 ug/mL	5.56 ug/mL
Dilution factor/from?	13.33 from stock	3 from Std 1	3 from Std 2	3 from Std 3
Volume of concentrate	40.55 uL	200uL	200uL	200uL
volume of diluent	459.45uL	400uL	400uL	400uL
final dilution of stock	150 ug/mL	50 ug/mL	16.67 ug/mL	5.56 ug/mL
final volume/tube	500 uL	600uL	600uL	600uL

1. First of all the tubes namely Std 1 and Std 2,3,4,5 will filled by 459.45uL and 400uL Diluent (eg Water) respectively.

2. Then for getting concentration of 150ug/mL in Std 1 tube, 40.55uL of from stock solution is pipetted in tube Std 1.

3. Now for getting conc. 50 ug/mL, 16.67 ug/mL and 5.56ug/mL in std 2,std3 and std4 , 200 uL from each tube starting from Std 1 is pipetted in adjacent tube.