Quantification of a mixture of peptides in solution was achieved by disposable patterned hydrophilic chip based matrix-assisted laser desorption/ionization mass spectrometric imaging（MALDI MSI）.Compared with other quantitative methods for peptides in solution, this method is label-free and does not require separation of the multiple components of the solution before analysis. Uniform hydrophilic spots and high mass accuracy measurements provided confident identification and quantitative analysis of imaged compounds. The linear correlation between concentration and grayscale of image in the range of 5 fmol/μ L to 1 pmol/μ L was obtained for all four peptides. Good sensitivity and excellent reproducibility were also achieved. The method expands the application of MALDI MSI from tissues to solutions.
Ting WuXiao-Hui YangChuan-Jing ZhangZhen-Ping WangYi-Ping Du
Primary aromatic amines （PAAs） are substances with toxicity and suspected human carcinogenicity. A facile method for highly sensitive detection of PAAs using surface-enhanced Raman spectroscopy （SERS） is reported. The immobilization of Au nanoparticles （AuNPs） on the glycidyl methacrylate-ethylene dimethacrylate （GMA-EDMA） materials makes the suhstrate a closely packed but not aggregated Au NP arrays which provides a prominent SERS enhancement. Four PAAs with different substituent groups, namely, p-toluidine, p-nitroaniline, benzidine and 4,4-methylene-bis-（2-chloroaniline） have been successfully identified and quantified. High sensitivity and good linear relationship between SERS signals and concentrations of PAAs are obtained for all four PAAs.
