If your MS is quantitative then yes the peak area will be proportional to the analyte concentration but you will not be able to account for small variations due to sampling. To do this (assuming you are confident your generation of samples from the meat is consistent) you will need to use an internal standard for normalisation. Prepare standard curves (SC) for each of your analytes and use an internal standard (IS) which you know will be in the same concentration both SC and experimental samples e.g. prepare SC dilutions, take 50 uL of each dilution and mix with 10 uL of suitable solvent containing IS. Prepare 50 uL experimental sample in the same way. Interpolate sample concentration as you would in any assay.