A nested multivariate chemometrics based calibration strategy for direct trace biometal analysis in soft tissue utilizing Energy Dispersive X-Ray Fluorescence (EDXRF) and scattering spectrometry

Highlights: • The X-Ray fluorescence and scatter regions can be utilized to derive comprehensive sample composition information. • Multivariate calibration techniques enhance direct rapid simultaneous analysis of trace biometals in model soft tissues. • The nested approach (ANN and PCR) for multivariate calibration is an efficient technique for direct quantitative analysis of specific trace elements in model soft tissue. - Abstract: Compton scatter-modulated fluorescence and multivariate chemometric (artificial neural network (ANN) and principal component regression (PCR)) calibration strategy was explored for direct rapid trace biometals (Mn, Fe, Cu, Zn, Se) analysis in "complex" matrices (model soft tissues). This involved spectral feature selection (multiple fluorescence signatures) normalized to or in conjunction with Compton scatter. ANN model resulted in more accurate trace biometal determination ($R^2>0.9$) compared to PCR. Hybrid nested (ANN and PCR) approach led to optimized accurate biometals' concentrations in Oyster tissue (≤ ± 10%).