Hi @smrts , welcome to the community.
This should be in the form of:
separate(data, col, into, sep = "QQ(?!.*QQ)")
The regex reads: QQ not followed by QQ (with any character zero or more times in between).
A couple of examples:
text1 <- "12345QQ78910"
text2 <- "123QQjabcQQd fQQ hijQQ789"
str_split(c(text1, text2), "QQ(?!.*QQ)")
#> [[1]]
#> [1] "12345" "78910"
#>
#> [[2]]
#> [1] "123QQjabcQQd fQQ hij" "789"
I guess you'll know how to use separate(), if any problem post a reprex (your code and example data).
Hope it helps.