I use regexp from this blog article which is about the same problem you are trying to solve.
See it here: http://www.kimgentes.com/worshiptech-web-tools-page/2008/10/14/regex-pattern-for-parsing-csv-files-with-embedded-commas-dou.html
In short ^(("(?:[^"]|"")*"|[^,]*)(,("(?:[^"]|"")*"|[^,]*))*)$
