# Hybridization Buffer (HT1) and Resuspension Buffer (RSB) alternatives and purchasing availability

\*\*Hybridization Buffer (HT1) is used for the final library dilution(s) following denaturation, prior to sequencing, and Resuspension Buffer (RSB) is a commonly used buffer in Illumina library preparation kits.

What can be used as a substitute for RSB when diluting libraries prior to sequencing?\*\*

* 10 mM Tris-HCl, pH 8.5 with 0.1% Tween 20.
* 10 mM Tris-HCl, pH 8.5.
* Nuclease free water can also be used\*. (\*Unless sequencing on NextSeq 1000/2000, in which case the RSB with Tween reagent is critical for clustering; if RSB with Tween is not available, use the first option above as a substitute for RSB with Tween.)

**What can be used as a substitute for HT1?**\
There are no officially recommended substitutes. Use HT1.

**Is RSB sold individually?**\
RSB is not available for purchase individually at this time.

**How can RSB with Tween be ordered, and when should it be used?**\
RSB with Tween must be used when diluting libraries for sequencing on the NextSeq 1000/2000. It is included in the NextSeq 1000/2000 sequencing reagent kits.

**Is HT1 sold individually?**\
Yes, it can be purchased [here](https://www.illumina.com/products/by-type/accessory-products/ht1-buffer.html).

**Is HT1 included in the Nextera XT library prep kits the same as the HT1 that is included in sequencing reagent kits?**\
Yes, the composition of the HT1 is the same in both, but the part numbers are different.

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