Please check whether my way to culculate the DNA concentrati

Please check whether my way to culculate the DNA concentration is correct or not.

I was requred to culculate the concentration of DNA bands ( in nanograms/ microlitter ) for each samples.

the 3 plasmid (pUC, unknown concentration) samples in 1, 2 ,3 chanber. pUC control (Concentraion = 1µg/12µl) is pur in canber 5, and DNA ladder ( concentration=1µg /12µg) is in chamber 7.

3 samples are loaded 20µl for each samples.

pUC control and DNA ladder are loaded 12 µl for each.

I used this DNA laddar

I\'ve made semi-log graph of DNA laddar (Y axis ; base paires X axis Migration distance (mm)) based on this DNA ruler.

and I culculated, for example.

a first band of samle 1 travels 10 mm. according to the semi-graph, its base pair =10000 bp and concentration is 20 ng/0.5 µg (as shown the figure of DNA ladder).

Concentration of pUC contorol and DNA ladder are both 1µg/12µl. In this point, they are loaded to 12µl. so both have 1µg/ 12µl *12 µl = 1 µg.

so 20ng/0.5µg* 1µg ( in the meaning of using 1µg instead od 0.5µg) = 40ng of plsamid DNA in the first band of sample 1. sample 1 is loaded for 20µl, so its concentraltion is 40ng/20µl for this band.

Is this way to determine the concentration correct?

if this way has any ploblem, please teach me

Solution

Hi,

Your aproach to the question is correct. The first DNA band has 40ng of DNA. The calculations are correct. You may have to calculate and add up the DNA concentration of each band and obtain the total DNA concentration for eac sample.