Ideally the UV will not affect the activity of ampicillin. The exposure time will remove excess moisture from the solidified agar based medium.

UV will not affect ampicillin stability. Don't worry about that. You can put your plates at any clean environment.

i've been preparing ampicillin plates without using UV light at all, as long as the environment is clean and sterile, it should be fine

UV does not affect ampicillin activity in any way. However, the pH changes will do affect the activity and that is why you should always use this antibiotic in freshly prepared media.

During the exposure of UV light in laminar hood, the warm media dispensed in Petri plates cause accumulation of water vapors on the lid of the plate. So during exposure to UV light (say 20 min or so) water condensation is avoided, and water evaporation avoids over lapping of bacterial cfu thus providing distinct colonies!

I agree with Dr.Kanwar. Indeed sometime we do forget certain small practical hints and then weep over spilt milk.

That's true. Application of microbiological techniques is a mind set. We shall assist younger researchers when ever possible!

No effect of UV light on ampicillin activity

Do not worry Dr Abir Chakraborty UV does not affect ampicillin activity. Go ahead with you expermint