Final answer:
To determine the concentration of the original DNA sample, use the Beer-Lambert law, calculate the concentration of the diluted sample from the provided absorbance, and then adjust that value to reflect the concentration in the original, undiluted sample.
Step-by-step explanation:
Determining DNA Concentration Using UV Spectroscopy
To calculate the concentration of double-stranded DNA in a sample, we utilize the Beer-Lambert law, which in molecular biology applications, connects absorbance with DNA concentration. Given the average value of ε (epsilon) as 0.020 μg/µL/cm for double-stranded DNA at the absorption maxima of 260 nm, and knowing the absorbance of a diluted DNA solution, we can infer the concentration of the original sample.
Based on the provided exercise, a solution with 50 microliters of DNA dissolved in 950 microliters of water exhibited an absorbance of 0.326 at 260 nm. Using the Beer-Lambert law (Abs = ε * c * l), and a path length (“l”) of 1 cm, the concentration (“c”) can be calculated by rearranging the equation to c = Abs / (ε * l). The calculated concentration of the diluted sample will then be adjusted to reflect the concentration of the original undiluted DNA sample.
The steps to measure the DNA concentration generally include blanking the spectrophotometer with a water sample, measuring the absorbance of the DNA solution, and calculating the DNA concentration using the Beer-Lambert law. The obtained concentration should be recorded in the desired units, which in this case is μg/μL.