Types of Calculations
To calculate the amino acid composition expressed as mole fraction
- Sum the # of nmoles of the individual amino acids (excluding the internal standard).
- Divide the amount of each amino acid by this sum.
To calculate the amino acid composition expressed as mole %
- Multiply the mole fractions by 100.
To calculate the amino acid composition expressed as weight %
- Multiply the # of nmoles of an amino acid by that amino acid residue’s molecular weight to convert nmoles to ngrams.
- Sum the # of ngrams of the individual amino acids (excluding the internal standard).
- Divide the weight of each AA by the sum to determine its weight fraction.
- Multiply the AA’s weight fraction by 100.
To calculate the sample protein concentration. (Na+)
- Multiply all underlined concentrations by the corresponding amino acid’s residue weight (excluding the norleucine standard).
- Sum these values.
- Multiply the sum by 2.0 (expected amount of internal standard per 50 uL) then divide by the actual amount of norleucine injected.
- Multiply by the value from 3.) by the total volume then divide by the injected volume. Concentration is in ngrams/total sample hydrolyzed.
- Divide the value from 4.) by the initial transfer volume. Concentration is in ngrams/uL of original sample. Divide by 1000 for mgs/mL.