For quantitative analysis:

First you have to get lambda max for that compound in suitable solvent ( the solvent is taken as reference).

You have to draw calibration curve for your working range at lambda max (get the calibration curve as linear as possible, regression constant (R2) value as near equal to 1) with your standard compound with different concentration.

Prepare your compound ready for that solvent (if the concentration of your compound is out of range then dilute the sample), never forget to add the dilution factor,while calculating the concentration.

to get maximum absorption is to reach the absorbance value is 2.

equation A = 2-log%T.

if your compound get higher absorbance than dilute it as such than you can get the maximum absorbance 2.

Regards

Chirag Mistry

It all depends on whether there is a UV active component in the compound or not. Hence, to find this out, prepare a solution of your compound and check the absorbance over a wide range of wavelengths, ie within the capacity of your equipment. The wavelength at which the highest signal (peak) is recorded is identified as the lambda max. Once this is present, the signal should be at least 3X the background, you can follow the suggestion of Chirag above. The usefulness of this lambda max will depend on the limit of detection (LOD) that you need for the compound. If the signal at the lambda max can go as low as the LOD you need, then the UV spectrophotometer can be sued to detect your compound.

you may study Fundamental analytical chemistry by Dugles H .Skoog page 518 edition 5th

I think this link is useful, 

http://www.instanano.com/characterization/theoretical/concentration-calculation-from-uv-vis-absorbance/

Determination of (a) Wavelength of Maximum absorbance (Lamda Max) and

(b) Absorptivity coefficient of Paracetamol

Wavelength of maximum absorption (Lamda Max) the extent to which a sample absorbs ligght depends upon the wavelength of light. the wavelength at which a subtance shows maximum absorbance is called absorption maximum or lamda max

the value of lamda max is important for several reasons.

1) This wavelength is characterstic of each compound

2) It provides information on the electronic structure of the analyte

3) It ensures highestsenstivity and minimize devialtionfrom Breets Law

Preparation of stock solution :

1. 5mg paracetamol power were weighed by elecgtronic balance

2. This power was taken in a a 50 mL volumetric flask and was field with distilled water upto the mark

3. The flask was shacked well untill the paracetamol powder was dissolved. this solution was the stock solution.

Preparation of working stock:

Take 10 mL of stock solution and dilute up to 100 mL with distilled water