Real lab failures, root causes, and fixes — curated and bilingually annotated by our team.
PCR yields little to no product visible on gel electrophoresis. Expected band is absent or extremely faint despite using standard reaction conditions.
Weak or absent PCR product. Primers are degraded or show primer-dimer formation at the bottom of gel.
Gel shows multiple bands, smears, or high background instead of single clean product band. May include primer-dimers at bottom of gel.
Sequencing shows errors, truncations, or unexpected sequences specifically at the 5′ or 3′ ends of amplified products.
No visible PCR product despite good template quality. Control reactions with different primers may work normally.
Sequencing reveals point mutations, insertions, or deletions within the amplified fragment that are not present in original template.
No product or very weak bands despite proper template and primer quality. Reaction components appear functional in other assays.
PCR products appear in negative control reactions without template. Products may appear in samples expected to be negative.
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