For several ions that can be separated in mass/charge by an instrument with a resolution of 30, average abundances are now known . Some abundances requiring separate mass and charge separation are also known, and the accuracy of these determinations is approximately 10%, see Table 1. This work is still in progress.
Ions with first ionization potentials less than 10 eV are overabundant by as much as a factor of 4 in the solar wind with respect to their abundances in the photosphere. This can be explained by preferential confinement in the local magnetic field moving with the protons. The magnitude of this FIP effect varies with the type of flow. The effect is smaller for flow from coronal holes than from active regions.
Solar wind abundances appear to vary depending upon the magnetic topology of the source region. This aspect of solar wind studies may point a way to the solution to the outstanding question of the origin of the slow solar wind.
With new instruments it will be possible to resolve major
isotopes beyond 
He and 
He and thus expand studies of the
isotopic constitution of the solar corona. From studies of the
He/
He ratio it appears that the outer convection zone of
the sun is well mixed. More extensive measurements of the
isotopic composition promise to provide isotopic ratios for the
sun as a body.
The pickup ions, derived from neutral atoms from the local interstellar medium, can be distinguished and measured in the solar wind beyond 1 A.U., making it possible to measure abundances in the LISM using a spacecraft in the locality of the earth. The dynamic characteristics of these ions profoundly affects the outer regions and termination of the heliosphere.
These advances show the that composition measurements in the solar wind are likely to be increasingly useful and rewarding for some time to come.
Acknowledgments. The authors appreciate the help and advice of G. Gloeckler, D. Reames, A. Lukasiak, and P. Bochsler. NASA has contributed to the support of this work under Grant NAG-5-1129.