FIGURE 13.1 - Diagram of a mini-gel used to determine the DNA concentrations of DNA samples q, r, and s. Four different concentrations of uncut lambda DNA are run in the first four lanes while the three samples are run in the following lanes. In this example, 5.0 µl of sample q stains with an intensity roughly equal to that of the 50 ng of 1X uncut lambda DNA. Because 5 µl of q DNA was placed in lane 5, the concentration of the undiluted DNA sample is about (50 ng/5 µl =) 10 ng/µl.