Get Help Sign In

Frequently asked questions

Our Scientific Applications Support team has assembled a list of frequently asked questions to help you find answers quickly. Filter using one or more categories to focus on specific topics, or use the search bar to perform a text search.

I’ve been using Tsug’s Rule to calculate the Tm of my oligonucleotide. Is that still the best method to calculate Tm?

While these rules of thumb offer a general approximation of Tm, there are better algorithms available that are free and easy to use, and that will provide an extremely accurate Tm estimation.

We offer one such algorithm for free use in our SciTools® OligoAnalyzer® application. This detailed equation takes into account the effects of sodium and magnesium on Tm calculations.

These cations have a significant impact on the functional Tm of an oligonucleotide in solution due to their charge. For the most accurate Tm estimation we recommend entering your sequence and adjusting the ionic concentrations in the OligoAnalyzer tool so that they match your reaction conditions.

You can view the exact algorithm used for our Tm calculations by clicking on the Definitions link in the OligoAnalyzer program.

Custom DNA & RNA

*RUO—For research use only. Not for use in diagnostic procedures. Unless otherwise agreed to in writing, IDT does not intend for these products to be used in clinical applications and does not warrant their fitness or suitability for any clinical diagnostic use. Purchaser is solely responsible for all decisions regarding the use of these products and any associated regulatory or legal obligations.