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Topic: Calculating dilution factor  (Read 280 times)

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Offline yourdeath01

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Calculating dilution factor
« on: February 01, 2021, 12:24:27 AM »
Here is the Q: If you add 1 μL of PBS buffer into 1000 μL of water, what is the dilution factor?

Isn't dilution factor calculated using this equation: X/X+Y=Z

X =  the volume to be transferred to successive tubes

Y = the volume of solution in each tube initially

Z = the dilution factor

So if I plug in

1uL/1uL+1000uL = 9.99x10-4 or 9.99e-4 or 0.0009

OR did I mess this up? Thank you!

Offline chenbeier

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Re: Calculating dilution factor
« Reply #1 on: February 01, 2021, 02:18:20 AM »
This is very small volume.
Normal procedure in Lab: Let say you have 1 ml put in 1000 ml = 1l. It is the same ratio like 1 μl to 1000 μl.
The procedure is to get a 1l measured flask add some of water add the 1 ml compound  and then fill up to the mark to 1 l. Then you have dilution 1 to 1000 or in your words X/Y =Z
Your calculation is also correct if you add 1 ml to 1 l or 1μl to 1000 μl

Offline yourdeath01

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Re: Calculating dilution factor
« Reply #2 on: February 01, 2021, 03:33:01 PM »
Thank you for the reply

So the formula used here:

Is different from the formula used from my class:

Using the first formula I get 1001 uL

Using formula from my class I get 1/1001 = 0.00099999 uL

The 1001 uL makes more sense for sure but I was not sure if the answer using the formula from my class also works maybe?

Offline mjc123

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Re: Calculating dilution factor
« Reply #3 on: February 01, 2021, 05:52:06 PM »
First, dilution factor is not a volume and does not have units.
Second, there are obviously two different definitions of "dilution factor" out there. Thus if you had, say, 1 mL of solution and diluted it to 10 mL, the dilution factor could be 10 (first definition) or 0.1 (second definition). Personally I would call that a 10-fold dilution.
The important thing is to be consistent with whichever definition you are using. And remember that dilution always reduces the concentration. So if your DF > 1, then C2 = C1/DF. If DF < 1, C2 = C1*DF.
Third, 9.99e-4 is not 0.0009 (but you corrected that).

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