I'm no chemist and my interpretation is dodgy but purification will (I guess) be to get 'clean' phosphine. But it's not needed pure in venus' atmosphere, it jus

I'm no chemist and my interpretation is dodgy but purification will (I guess) be to get 'clean' phosphine. But it's not needed pure in venus' atmosphere, it just has to exist. IOW you don't have to purify phosphine to bring it into existence.