Hierarchical clustering reveals production batches.

<p>Batches were identified by hierarchical clustering with the programme Cluster 3.0 [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0168289#pone.0168289.ref071" target="_blank">71</a>], and visualised using Treeview [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0168289#pone.0168289.ref072" target="_blank">72</a>]. Pearson correlation (uncentered, with average linkage) was carried out on log₂-transformed, mean-centered data that had been normalised for each element, and are shown on a false colour scale (right). Samples belonging to the same batch display highly correlated compositional profiles.