[nerdzrus04]

Is this formula for calculating the mass in percentage of an analyte in a substance correct?

This is the formula:

 concentration in mol/dm^{3
___________________________
 amount/mass of substance used}   

[fledarmus]

I'm not sure exactly what you're asking or what context it is in, so take this answer for what it is worth:

Mass% is a ratio of two masses. I think what you are looking for is

Mass of the analyte
Mass of the total sample

(multiply by 100 for percent...)

Usually you work this out by finding the concentration of the analyte in a volume of some extraction solvent, then backcalculating to find the mass of the analyte.