how would you make a 4% percent paraformaldehyde solution?

Work:
starting from 20% (diluted with PBS)
V1C1=V2C2
(100)(20)=(x)(4)
x=500
so add
496 ml of PBS (accounting for 4% paraformaldehyde) or would you add 500ml of PBS

Thank you

To make a 4% paraformaldehyde solution starting from a 20% solution that is diluted with PBS, you can use the formula V1C1 = V2C2, where V1 and C1 are the volume and concentration of the starting solution, and V2 and C2 are the volume and concentration of the desired solution.

In this case, you have V1 = 100 ml (since the starting solution is 20% and you need to dilute it to make the desired 4% solution) and C1 = 20%. You want to find V2, which is the volume of the starting solution you need to mix with PBS in order to get the desired 4% concentration, and C2 = 4%.

Plugging these variables into the formula: (100)(20) = (V2)(4)

Simplifying the equation: 2000 = 4V2

Dividing both sides by 4: V2 ≈ 500 ml

Therefore, you need to add approximately 500 ml of PBS (Phosphate Buffered Saline) to the starting 20% paraformaldehyde solution in order to achieve a final volume of 600 ml with a 4% paraformaldehyde concentration.