To use the internal standard norleucine (nle) for calculation make up a stock solution and add to your amino acid calibration standard to give a final concentration of 10nmol nle/20 microlitres of standard loaded. For sample preparation add this stock solution to your sulphosalicylic acid deproteinisation solution to give a final loaded amount of 10nmol nle, i.e. if your loading volume is 50 microlitres the nle conc required is 10nmol/50 microlitres. To calculate amino acids following preparation and check for sample losses, select the internal standard report option in your method and fill in the peak table with nle selected in the internal std id column.
If this does not answer your question or solve your problem, then please contact us at support@biochrom.co.uk detailing your question or the problem you are experiencing. Please list if relevant the instrument, software and version numbers you are running, and enclose any relevant data files, etc.