Dear Allym2506,
Sorry, it’s very difficult to figure out/interpret what you really did.
If I assume, that your 3.36 * 10^-4 moldm^3 should mean in real 3.36 * 10-4 mole/dm3 what would be the same as 3.36 * 10-4 mole/Liter, then an easy solution is possible:
(Maybe you have forgotten to write the “Slash” for the Division. - I hope so!)
In this case you must know, if you have to determine the concentration in (i) g/cm3 (= g/ml) or just as (ii) mole/cm3, or (iii) the whole amount of the sample (g/250 cm3 = g/Tablet).
In all three cases the cuvette size is not used anymore, because your number is already a concentration.
For (i):
You have first to get the “Molecular Weight” (MW = g/mole) of your Salicylate and calculate:
c = 3.36 * 10-4 mole / 1000 cm3 * MW
For (ii):
c = 3.36 * 10-4 mole / 1000 cm3
For (iii):
c = 3.36 * 10-4 mole / 1000 cm3 * 250 cm3 * MW
But I could not figure out, what you really have and for what correctly you are asking.
I hope this may bee anyway of some help to you!
Good Luck!
ARGOS++