Try it this way

    sFormula = "=IF(ISNUMBER(FIND(" & Chr(34) & sReturn & Chr(34) & ",RC[-1])),LEFT(RC[-1],FIND(" & Chr(34) & sReturn & Chr(34) & ",RC[-1])-1),"""")"


    ActiveCell(i + 1, 0).FormulaR1C1 = sFormula