Table I. Se speciation in Opuntia tissue by μXANES spectroscopy.
Results of the least squares LCF of Se K-edge XANES spectra are shown. The best LCF was obtained by minimizing the normalized sum-squares residuals [NSS = 100 × Σ(μexp – μfit)2/Σ(μexp)2], where μ is the normalized absorbance. Error on percentages is estimated to ±10%. Selenodiglutathione, SeCys, SeCystine, and elemental Se0 were not detected (ND). Se0 is both red and gray elemental forms.
| Frozen Opuntia Tissue, Location | NSS | SeO42− | SeO32− | SeMet |
| Cladode tip | 8.12E-04 | 21 | ND | 79 |
| Cladode base | 6.67E-04 | ND | 9 | 91 |
| Seed 2B left | 4.81E-04 | ND | 4 | 96 |
| Seed 2B right | 4.24E-04 | ND | 3 | 97 |