Indirect referencing to an internal standard is the most reliable referencing method in biololecular NMR. IndirectRef represents a simple HTML-program for the referencing of heteronuclear spectra to internal DSS. Actually, 2H-, 13C-,15N-, 19F-, 31P- and 129Xe-resonance frequencies can be calculated from the 1H-resonance frequency of DSS. The heteronuclear reference value has either determined from atoms of the methyl group of DSS itself or from the reference contained in a sphere/capillary immersed in the DSS solution. The following Ξ-values are used:
2H (0.153506088) (Markley et al., 1998, Pure Appl. Chem. 70, 117-142), DSS-CD3
19F (0.940866982) (Maurer and Kalbitzer, 1996, J. Magn. Reson. B113, 177-178), sphere TFA
13C (0.251449530) (Wishart et al., 1995, J. Biomol. NMR 6, 135-140), DSS-CD3
15N (0.101329118) (Wishart et al. 1995, J. Biomol. NMR 6, 135-140), capillary with liquid NH3
31P (0.404807356) (Maurer and Kalbitzer, 1996, J. Magn. Reson. B113, 177-178), sphere H3PO4
129Xe (0.276604018) (Kalbitzer, to be published), sphere Xe-gas