Evaluate the collective function of references cited together in a given text segment.
Classify their combined role into one of the following categories: 'method', 'background', or 'result'.

Text:Following precipitation with 0.3MNaAc and 2× volume of ethanol, the RNA was treated with DNAseI (Sigma) and quantified in a NanoDrop 1000 Spectrophotometer.
Category: