Dilution problem

Question

For this lab we will dilute by factors of 10. Clearly indicate (often a table is best) how you generated each concentration of drug. Our stock solution is 10% and we need 100ml of acetylcholine at 0.1%. The samples were tested in 10.0 μg/mL 20.0 μg/mL 30.0 μg/mL. Totatlly confused

Answer 1

I'll assume the stock is 10% acetylcholine (mass/volume). That being the case, the stock would be 10 g in 100 ml of solution. To get 100 ml of 0.1%, we would do the following:

(x ml)(10 %) = (100 ml )(0.1%)

x = 1 ml of 10% stock diluted to a final volume of 100 ml. This will then be 100 ml of 0.1%

If you now want to dilute THIS new solution so as to get 10, 20 and 30 ug/ml, we should first convert this solution into ug/ml instead of %.

0.1% = 0.1 g/100 ml = 0.001 g/ml = 1 mg/ml = 1000 ug/ml

Now, we can dilute this to get 30 ug/ml, 20 ug/ml and 10 ug/ml

To get 10 ug/ml, dilute the 0.1% solution (1000 ug/ml) 1:100, e.g. 0.1 ml diluted to 10 ml

To get 20 ug/ml, dilute the 0.1% solution 1:50, e.g. 0.1 ml diluted to 5 ml

To get 30 ug/ml, dilute the 0.1% solution 1:33.3, e.g. 0.30 ml diluted to 10 ml