Investigating matrix effects of different combinations of lipids and peptides on TOF-SIMS data.

Matrix effects, which cause a change in ion intensity, occur in mass spectrometry methods including time-of-flight secondary ion mass spectrometry (TOF-SIMS). Matrix effects often cause large issues in quantitative analysis because secondary ions related to a particular molecule could be dramatically enhanced or suppressed regardless of the concentration. To investigate matrix effects in biological samples, the authors evaluated mixed lipid {POPC [1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine, molecular weight (MW) 759.6]}, peptide [leu-enkephalin, neo-leu-enkephalin (amino acid sequence: YAGFL, MW 569.3), and neo-angiotensin II (amino acid sequence: DRVYIHAF, MW 1019.5)] samples. Matrix effect features were investigated by analyzing the concentration dependence of secondary ions in lipid-peptide mixed samples to develop a method that enables quantitative analysis using TOF-SIMS. Matrix effects depended on the lipid-peptide combination. Interestingly, some secondary ions possessed an intensity that was highly dependent on concentration.