You do not have to do anything special. If you have a spectrophotometer with a UV lamp, i.e. providing light of 280 nm, you just have to put your sample in a quartz cuvette and read. I suggest you to read absorbance instead of optical density. If your sample goes up to 2 or 3 of absorbance, dilute the sample to have your readings between 0 and 1. You may consider to use bovine dilutions serum albumin as reference. Dilutions better in a buffer.

yeah my sample optical density is 0.2 i am running this as positive control is this ok

In principle this is OK