Converting ppm to fmol/mg

It is important that a consistent set of atomic units (e.g., fmol, fmol/mg, nmol/g) is used for all data (except for [C]). It is customary, however, for published data to be expressed in units of concentration, commonly ppm for U, Th and Sm, and ncc/mg for He. One fmol/mg equals:

0.238028913 ppm U
0.2320381 ppm Th
0.15036 ppm Sm
22.414 ncc/mg He

Simply divide the concentrations by these numbers for use in HelioPlot. This would also be a good time to apply the α-ejection correction.

See entering data, importing data, α-ejection correction