Well, if you really are just looking to get the last word, you could do something like this...Assuming of course, that you make a string equal to the text of your rich text box.
string str="hello, how are you doing?";
if (str.Length >0)
{
int index=str.LastIndexOf(" ") + 1;
str = str.Substring(index));
}
Then just return the string, and do what you need to do with it.
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