Hello, I am running many sample of PCR products ( with expected bands at 400 bp size). The marker I use is 100 bp ladder. In a gel, I made two rows of sample wells, which turned out to always show 2 main problems.
1. There is a strong bright line cutting across the upper part of the gel
2. The lower area of the gel (or the second row of sample well area) is many times showing faded bands (including DNA ladder, which should be in the most left lane).
I use 4uL of 100bp DNA ladder. Regarding to samples, it is from 2 uL PCR products + 2 uL DI water + 1 uL 5X loading dye.
I use 120 V for around 30 minute, and then 15 post staining in Gel Red and another 15 min in DI water.
The picture is attached.
Can anyone help me explain what is happening and how to solve these problem?
Thank you so much