How can I use regex to match a character (') when not following a specific character (?)?

How can I write a regex pattern to split a string by a specific delimiter as long as it's not preceded by a question mark? I've written a parser that splits an EDIFACT message into segments, composites and elements. But in the EDI standard the question mark is an escape character. So to split this string: ``` 'PRI+2.005:1+9022.5'RAD+RRHANB97+120814' ``` I can use string.Split('\''), and then string.split('+') and then string.split(':') to get PRI, 2.005, 1, 9022.5 and so on However, these characters can be escaped by a question mark: ``` 'PRI+2.005?+3.2:1+9022.5'RAD?'R+RRHANB97+120814' ``` which should now be PRI, 2.005+3.2, 1, 9022.5, RAD'R, RRHANB97. Can someone help with a regular expression that would match the ' and not the ?'? Thanks