Check in Compressor presets -Apple/Quicktime for the Apple PR422 preset.
If you can't find it you can just customize a existing preset.
Apply preset to clip.
Inspector window/encoder tab(under description/2nd from left)
Change video settings to PR422
change audio settings: (enable if not already)
Format linear PCM
Sample size 24 bit
If this doesn't work it might help to understand what your sequence settings are and/or what QT says the file is when you command+I.