Patent ID: 8219325

Claim:
A method for determining the ratio of two distinct target-peptides or -polynucleic acids comprising: (a) obtaining a sample containing said two distinct target-peptides or polynucleic acids, (b) providing a precursor-peptide or precursor-polynucleic acid, comprising the two distinct target-peptides or -polynucleic acids in a known ratio, wherein the two distinct target-peptides or polynucleic acids are connected by a cleavage site, (c) cleaving the precursor-peptide or precursor-polynucleic acid at the cleavage site to obtain a standard with the known ratio of the two distinct target-peptides or polynucleic acids, (d) detecting a signal of each distinct target-peptide or polynucleic acid of the standard in an analyzer, comparing the signals with the known ratio and determining a correction factor, (e) detecting the signal of each distinct target-peptide or polynucleic acid of the sample in the analyzer and (f) determining the ratio of the two distinct target-peptides or -polynucleic acids by means of the correction factor.