You can find the density from place where you ordered and/or on the package/bottle of the reagent. In sigma aldrich's site it is given that d=1.03 g/mL
Which means, in 1L of solution you have m/1000mL=1.03g/mL m=1030g
Now, to get 1mM solution of 50mL you should have 224.3/(1000/(1000/50))=11.2mg
11.2mg will correspond to 1.09x10^-5 of the 1L solution, which will be 10.9 microlitres of solution. Considering the fact the it is %95 solution, you should have 10.9/0.95=11.5microliters taken from stock solution and filled with the solvent to fill 50mL solution.
1M 100% methyljasmonate = 224.3 g/Liter; since you have 95% methyljasmonate you should use 236.1 g/Liter to obtain 1M.
1mM = 236.1 mg/Liter; since you need only 50 mL;
50/1000 x 236.1 = 11.81 mg; therefore for obtaining 50 mL of 1mM solution you should wegh 11.81 mg of 95% methyljasmonate, dissolved in sufficient quantity of the solvent and complete the volume to 50 mL.
You can find the density from place where you ordered and/or on the package/bottle of the reagent. In sigma aldrich's site it is given that d=1.03 g/mL
Which means, in 1L of solution you have m/1000mL=1.03g/mL m=1030g
Now, to get 1mM solution of 50mL you should have 224.3/(1000/(1000/50))=11.2mg
11.2mg will correspond to 1.09x10^-5 of the 1L solution, which will be 10.9 microlitres of solution. Considering the fact the it is %95 solution, you should have 10.9/0.95=11.5microliters taken from stock solution and filled with the solvent to fill 50mL solution.
As Elbay wrote: you should check the density of the product and if is hard to take small volumes you might take 10-fold volume and then make a dilution of 10.
There is a much simpler way to figure this, i have been on this thread for ages and Elbay there is an error in your calculations
As it is given as 95%, you can see that is 95g per 100ml, but molarity is based upon litres, so you must * this total by 10 to reconvert to litre scale (950g/L). This can then be divided by the formula weight of pure MeJa 95% stock (224.3g/mol)
(950)*10
------------------------------- = 4.235 M
224.3
So now we know the stock itself has the concentration of 4.235 M it is simple enough to get your required amount
So with a 4.235 M stock, which you want to produce 50ml of 1mM stock, you need to add 11.8 ul of MeJa 95% stock
Hope that helps
[EDIT 27.10.19 : I have edited this post to simplify and have a full written explanation below]
Ganesan Mahendran I have edited my first comment in the hopes it has simplified the working, and also have attached a full breakdown of the calculations