In most cfDNA library preparation protocols, Buffer EB (elution buffer) is a low-salt buffer, typically composed of 10 mM Tris-Cl, pH 8.5, used to elute DNA after purification steps. It's specifically designed to stabilize nucleic acids, especially in downstream enzymatic reactions like ligation or PCR.

Yes, you can temporarily substitute Buffer EB with nuclease-free water for eluting DNA if:

• You will immediately use the eluted DNA for the next library prep step or sequencing.
• You are not storing the DNA for any prolonged period.
• You are working with high-purity, nuclease-free reagents to avoid degradation.