ffmpeg – extract 24bit stereo wav to l/r mono wavs while preserving 24bit?

i used the following to extract mono l and r wavs from a 24bit stereo wav file but the result is two 16bit files:

ffmpeg -i stereo24bit.wav -map_channel 0.0.0 left.wav -map_channel 0.0.1 right.wav

what do i add to this or how do i change it to preserve the 24bit depth of the original? searching has not turned up an answer to this. lots of similar but not this.

thanks, babag