> Thanks David, I'll take it from that there's no straightforward
> modification to the regex...

one man's straight forward is another's crooked I suspect...
other things that come to mind are

\s*"?([^"]*"?|[^,]+)\s*

then you can just use group 1 as before,

depends a bit on whether you want to tolerate dubious input, that last
one will behave diferently to  mis-matched " for example.