Multiple point internal standard calibration curves between the concentration ratios of fatty acids ( i.e. , C@ :@ , C@ :@ , C@ :@ , C@ :@ , C@ :@ , and C@ :@ ) to internal standards ( C@ :@ for C@ :@ , C@ :@ , C@ :@ , and C@ :@ , C@ :@ for C@ :@ and C@ :@ ) and their corresponding intensity ratios were established with a correlation coefficient of greater than @ .