Here is a generic formula for obtaining the Nth field in a delimited text string...
=IF($A1="","",IF(fieldnumber=1,LEFT($A1,FIND(delimiter,$A1)-1),TRIM(MID(SUBSTITUTE($A1,delimiter,REPT(" ",LEN($A1))),LEN($A1)*(fieldnumber-1),LEN($A1)))))
Simply replace the two occurrences of the word "delimiter" with the text that is delimiting the fields (a comma for your current question) and replace the two occurrences of the word "fieldnumber" with the number of the field you want (1 is the field before the first comma, 2 is the field before the second comma, etc.). So, if A1 held the text you wanted to parse and B1 contained the field number you wanted, then this is the formula you would use for you comma delimited question...
=IF($A1="","",IF(B1=1,LEFT($A1,FIND(",",$A1)-1),TRIM(MID(SUBSTITUTE($A1,",",REPT(" ",LEN($A1))),LEN($A1)*(B1-1),LEN($A1)))))