Total RNA concentration - (Nov/02/2007 )

how do i calculate total RNA concentration with spectrophotometer? i am measuring total RNA but i obtain very low absorbance??

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This is what I usually do...

Use 2-5ul total RNA and dilute to 70ul in DEPC water or TE Buffer.
Measure abs at 260/280nm (Be careful, ratio will differ depending on water or TE)
If Abs at 260nm = 1 = 40ug/ml RNA

Eg: If Abs at 260 = 0.4 when diluted 2ul to 70ul
= 0.4 x 40 x 70/2
= 560ug/ml

Hope this helps
Happy Friday!

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