Support matrix effects in the reversed-phase thin-layer chromatography of some peptides

The retentions of 28 peptides in reversed-phase thin-layer chromatography (RPTLC) were determined on cellulose and on impregnated cellulose and alumina layers with 1-propanol as the organic component of the mobile phase. Each peptide showed a support matrix effect: their RM values first decreased to a minimum, then increased with increasing 1-propanol concentration. On cellulose layers only the increasing phase was observed. The retention behaviour of peptides was adequately described with a quadratic or linear function, but the slope value of the linear function had a positive value. The results demonstrate that the support matrix effect can be observed on non-silica supports and it may occur in reversed-phase chromatography in the case of polar solutes and supports with free adsorptive centres on their surfaces. Both the intercept and slope values of the function are needed to describe the lipophilicity of peptides, but the correlation is not strong enough for the determination of the lipophilicity of peptides by RPTLC. Principal component analysis showed that the peptides form distinct clusters on the basis of their retention characteristics: peptides containing a basic amino acid, peptides with a ring structure in the amino acid side-chain and peptides containing uncharged amino acids.