PCA score plots with different normalisation methods.

<p>Cancer subjects are labelled in red, controls in blue and QCs in green. The vector from diamond to 5-point star is labelled in black, to 4-point star in green and to inverted triangle in purple. (A–C) Normalisation to creatinine, MSTUS and osmolality respectively. (D) raw data without normalisation.</p

The statistical results for biomarkers surviving testing against a new cohort of patients.

a<p>: identified by accurate mass and MS² fragmentation.</p>b<p>: only identified by accurate mass in the in-house database.</p>c<p>: only elemental composition predicted formula (<3 ppm).</p

LC-HRMS/MS results of isomers of C₅H₁₀N₂O₃.

<p>Extracted ion chromatograms under 4 different LC-HRMS conditions (A) and the interpretation of their MS² fragmentations (B).</p

Clinicopathological characteristics of the tumor patients.

<p><b>GS = Gleason Score T = T stages N = N stages M = M stages.</b></p

The numbers of remaining features and their percentages after each data filter.

<p>The numbers of remaining features and their percentages after each data filter.</p

OPLS-DA score plot with different normalisation methods.

<p>Cancer subjects are shaped as squares and controls as circles. The training set is labelled in filled red and the test set in hollowed blue. The four selected subjects and the vectors are same shaped and coloured as <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0065880#pone-0065880-g001" target="_blank">Figure 1</a>.</p