In all sources the 6th L.H. quaver, when interpreted literally, is a b, since it is not preceded by any accidental. The comparison with the analogous motifs in bar 37 and 201 proves Chopin's patent mistake, as he forgot to put a 
which would restore b
. Bar 37 is particularly significant, in which A does not include a to this note either, yet in this case its sound is unquestionable due to b2 in the R.H. part.
Compare the passage in the sources »
category imprint: Interpretations within context
issues: Omissions to cancel alteration
notation: Pitch