"prepare 500ml of agarose with EtBr 0.5microgram/ml. you have a
stock solution of EtBr at 1mg/ml. how much EtBr u use"
Let me try explain again..
you want 500 mls of agrose containing EtBr at 0.5 microgram per ml.
That means finally inside that 500ml of gel you must have 250
microgram of the EtBR right? ie. if you have 250 microgram of the
EtBr in a test tube, you just add that amount into 500mls of gel
stock, you get the concentration you want,ok?
Now where do we find that 250microgram of EtBr? In your EtBr
stock.
YOur EtBr stock has a concentration of 1 milligram per millilitre,
which is the same as 1 microgram per microlittre, agree?
So if you pour out 250 microlitre of the EtBr stock into a test
tube, you will have 250 microgram of EtBr, right?
So you have found your 250 microgram of EtBr you need for your gel.
Just pour that 250 microlitre of EtBr into your 500 ml of agarose
stock lor.
