correct!! you can use that UV machine to measure concentration ja. For e value, it depends on what diameter of particle size you would like to detect. If your particle size is 20 nm, you have to search e of that particular size and also set wavelength at that point. They will report both of e and waveleght for that value for you ja. err...you defend already, aren't you???? How come you just wanna know concentration? For your paper???? Congratulations in advance on your graduation na ja my sis ^^