Rapid Identification and Quantitative Analysis of Polycarboxylate Superplasticizers Using ATR-FTIR Spectroscopy Combined with Chemometric Methods

Table 2

Results of principal component analysis.

Number of principal components	Eigenvalue	Variance contribution (%)	Cumulative variance contribution (%)
1	0.6521	0.5426	0.5426
2	0.2556	0.2127	0.7553
3	0.2413	0.2008	0.9561
4	0.0343	0.0286	0.9847
5	0.0076	0.0063	0.9910
6	0.0063	0.0053	0.9963
7	0.0013	0.0011	0.9974
8	0.0008	0.0007	0.9981
9	0.0004	0.0004	0.9984
10	0.0004	0.0003	0.9988
11	0.0003	0.0003	0.9990
12	0.0002	0.0002	0.9992