Fig. 4

Unsupervised multivariate data analyses of two marjoram samples volatile compounds detected using GC-MS (n = 3). (A) PCA score plot of PC1 vs. PC2 scores of samples analyzed by HS-SPME GC-MS. (B) The respective loading plot for PC1 and PC2, provide peak assignments. (C) PCA score plot of PC1 vs. PC2 scores of samples analyzed by petroleum ether extraction coupled with GC-MS. (D) The respective loading plot for PC1 and PC2, provide peak assignments. The metabolite clusters are placed in two-dimensional space at the distinct locations defined by two vectors of principal component.