6x5 LC-MS/MS Peptide Reference Mix

The 6 x 5 LC-MS/MS Peptide Reference Mix is a unique reagent designed to monitor liquid chromatography (LC) and mass spectrometry (MS) instrument performance and assist in method development and optimization. The product is a mixture of 30 peptides: 6 sets of 5 isotopologues of the same peptide sequence. The isotopologues differ only by the number of stable, heavy-labeled amino acids incorporated into the sequence. The labels consist of uniform 13C and 15N atoms. Chromatographically, each of the isotopologues is indistinguishable; however, since they differ in mass, they are clearly resolved by mass spectrometry. The isotopologues of each peptide are present in a series of tenfold dilutions. This format allows assessment of instrument dynamic range and sensitivity from a single run. Peptides with a wide range of hydrophobicities were chosen to enable reporting of LC column performance. In addition, the peptides were chosen for maximal stability.