A laboratory technician is required to prepare a quarter normal saline solution (0.22% w/v) from the stock normal saline solution.

Question

1. What is the dilution factor required?

I have 4-fold dilution - is that correct?

2. Ise this dilution factor to calculate the volume of stock needed if one litre of the diluted solution is to be prepared.

I have 0.22 over (divided by) 0.91 = 0.2417582 - is that correct? And how do I then convert it into a fraction in its lowest form?

Thanks.

Answer 1

I don't know how accurately you want this done but I would think a quarter normal solution would be 0.91/4 = 0.2275 in which case 4-fold dilution is needed.

2. I don't think it is needed.
If we use M x mL = M x mL, then
0.91/100 x mL = 0.2275/100 x 1,000
mL = 0.2275*1000/0.91 = 250. mL.

Answer 2

Hi DrBob222,

Thanks for your help.
:-)