Test for ':' first, then take test string up to ':' or end, depending on if it was found
Dim strResult As String
' Position of :
intPos = InStr(1, strTest, ":")
If intPos > 0 Then
' : found, so take up to :
strResult = Left(strTest, intPos - 1)
Else
' : not found, so take whole string
strResult = strTest
End If