Hi Ahmed,

You can find very useful molarity calculator tools on the internet such as

http://www.graphpad.com/quickcalcs/Molarityform.cfm

Find the Guaiacol molecular weight and decide your final volume.

Good luck!

thank you Dr

i have M.wt and density and concentration %

i can calculate through 

MXVXM.Wt/dX%

(1.11 g/ml) / (124.14 g/mole) x (1000 ml/L) = 8.94 M for pure guaiacol liquid

For 1 liter of 0.0005 M, dilute 0.0005 M / 8.94 M X 1000 ml = 0.0559 ml ( = 55.9 µl) up to 1 L.

Dear Ahmed,

You said you have a liquid solution. So you should use the formula

M1xV1=M2xV2

M1: Concentration of Stock solution

V1: Stock volume you have to take it from

M2: 0.5 mM

V2: the volume of 0.5 mM solution

Dear Adam B Shapiro and Dear ahmed 55.9 ml is wrong and 55.9ul is correct.

Thanks for pointing out the error. I corrected my answer. Better late than never, I guess.

Thank you