Optimal Matrix Preparation Methods for Matrix-assisted Laser Desorption/ionisation Time-of-flight Mass Spectrometry Profiling of Low Molecular Weight Peptides in Human Saliva and Serum Samples.

Abstract

To develop standard experimental methods to minimise technical variance in matrix preparation for MALDI-TOF MS (matrix-assisted laser desorption/ionisation time-offlight) profiling. Matrix factors in saliva and serum samples of 20 healthy volunteers were examined, assuring their peptide components using seven different matrix type/preparation methods, HCCA(a-cyano-4-hydroxycinnamic acid)/SM(sample/matrix), SA(sinapinic acid)/DD(dried droplet), SA/SM, DHB(2.5-dihydroxyhenz-zoic acid)/DD, DHB/SM, DHAP(2.5-dihydroxyacetophenone)/ DD, DHAP/SM. Number of peaks, S/N(signal to noise) ratio and approximate range of target peaks were set as main selection criteria to find if these spell out any common regularity in results. Different methods perform differently. DHB/DD performed worst in both samples, with no effective peak detected. For saliva sample, the S/N ratios of other six methods were lower. M/z range distributed differently. DHB/SM and DHAP/DD performed best in number of peaks, m/z distributing in 1000 to 2000 account for the vast majority. For serum sample, S/N ratios and m/z range distribution were different in different methods. S/N ratio of SA/DD and SA/SM were higher, number of peaks and m/z distribution were not irreplaceable. S/N ratios of the other four methods were lower. DHAP/DD and HCCA/SM performed best in number of peaks, m/z in 5000 - 7000 account for the vast majority in HCCA/SM and 1000 - 2000 in DHAP/DD. Further studies should focus on other characteristics of peptide components detected in different matrix methods to increase evidence when selecting matrix type/preparation methods.