FAQ: Should I use Guanidine HCl (B2619A) in colorimetric LAMP reactions?

We recommend colorimetric LAMP reactions contain a final concentration of 40 mM Guanidine HCl and accordingly provide it for addition to the LAMP reaction in the standard SARS-CoV-2 workflow. However, some upstream sample prep workflows may introduce a source of guanidine into the sample which can be carried into the LAMP reaction. If guanidine will be carried into the reaction with the input material, we recommend not exceeding 60 mM in the final reaction and replacing the volume allotted for guanidine HCl with nuclease-free water.

Guanidine enhances isothermal amplification, yielding faster detection of SARS-CoV-2 RNA.

Colorimetric LAMP was carried out using purified positive samples (10 ng/ul human total RNA + synthetic SARS-CoV-2 RNA at 10,000 copies per reaction). E1 or N2 primer sets from the SARS-CoV-2 Rapid Colorimetric LAMP Assay Kit were used as indicated, and amplification was monitored in real time using a fluorescent dye. For both primer sets, addition of guanidine HCl to a final concentration of 40-60 mM enhanced amplification, resulting in earlier detection and enhanced color change.