Feasibility Study on the Use of a Portable NIR Spectrometer and Multivariate Data Analysis to Discriminate and Quantify Adulteration in Fertilizer

Table 4

Optimum performance of different quantification models for fertilizer A.

Model	R^2	RMSECV	Bias	R^2	RMSEP	Bias	RPD
PLS	0.9351	0.1297	0.0094	0.9450	0.1201	0.0133	3.0767
iPLS	0.9346	0.1302	−0.0003	0.9433	0.1227	−0.0045	3.0128
Bi-PLS	0.9424	0.1224	−0.0005	0.9299	0.1362	−0.0134	2.7141
Si-PLS	0.9496	0.1147	0.0004	0.9529	0.1122	−0.0076	3.2947
GAPLS	0.9409	0.1240	−0.0011	0.9493	0.1157	0.0010	3.1950
		Variables			Selected wavelength range (nm)
PLS		331			740–1070
iPLS		16			927–942
Bi-PLS		50			825–841, 927–942, 959–975
Si-PLS		58			820–839, 938–956, 995–1013
GAPLS		331			740–1070