Although agarose gel electrophoresis is a fundamental molecular biology technique, mysterious issues are endless. This article lists 10 of the most common failures, formatted as symptom → diagnosis → solution.

Q1: Band smearing

1. Check DNA degradation (re-purify + run original control)
2. Reduce loading amount (≤ 100 ng/band recommended)
3. Switch to low-EEO agarose (e.g. Radical™ AG1200LE)

Q2: Band smiling

1. Reduce voltage to ≤ 80 V to avoid overheating
2. Ensure buffer covers gel by 2–3 mm
3. Use 1× TAE for better heat dissipation

Q3: Band curvature

1. Uneven gel solidification, re-microwave until fully dissolved
2. Damaged wells, switch to wide-tooth comb
3. Uneven electric field, replace electrode buffer

Q4: Ghost bands

1. Incomplete digestion, add enzyme and incubate 30 min at 37°C
2. Primer dimers, reduce primer concentration to 0.1 μM
3. Genomic DNA contamination, use column-based purification

Q5–Q10 cover weak/missing bands, white wells, gel not solidifying, marker misalignment, voltage anomalies. Full version with diagrams available in the lab manual.

For persistent issues, Zechin Bio technical support offers remote assistance (WeChat / email / phone, response within 30 min).