Avaliação dos métodos Walkley & Black e CHN como métodos de referência para calibração multivariada na determinação de carbono orgânico em solos brasileiros

Abstract

The modified Walkley & Black method (Embrapa method) and CHN were evaluated as reference methods to determine organic carbon in Brazilian soils using near infrared spectroscopy (NIRS) as an alternative. The main objective of this study was to evaluate which of the reference methods could provide a calibration model with higher predictive ability. The models were mean centered and built from partial least squares (PLS) with ten latent variables. The modified Walkley & Black presented a lower accuracy when compared to CHN as reference method for near infrared spectroscopy.Other figures of merit such as sensitivity, analytical sensitivity, detection and quantification limits, adjust and linearity presented results very similar. A paired t-test was applied to the results of figures of merit obtained from both models and with 95% confidence did not show significant differences between the two methods used as reference for NIRS.