3.1.1. Exploratory data-analysis
A simple PCA was performed, retaining only 2 principal components (PCs) since 95.5% of the total variance was explained (PC1 = 91.9% and PC2 = 3.6%). The resulting score plot (Fig. 3) shows a faint clustering. Four groups of samples can be separated to a certain extent: (1) samples containing sildenafil of which most samples Apatinib situated in the top left corner, (2) placebo samples in the lower part of the score plot, (3) samples containing tadalafil which are mostly concentrated between the two large groups of placebo samples and samples containing sildenafil and (4) samples containing both sildenafil and tadalafil which are mostly clustered on the right part of the score plot. Study of the loading plot (figure not shown) did not reveal any absorbance values which could account for amoebocytes clustering, thereby showing that the entire fingerprints account for the obtained discrimination.
Fig. 3. Score plot obtained with Principal Component Analysis.Figure optionsDownload full-size imageDownload as PowerPoint slide