Mass spectrometry is one of the most used methods for the analysis and identification of amino acids and other biological molecules as well as the sequencing of protein and DNA. Matrix-assisted laser desorption/ionization (MALDI) due to the soft ionization and lower fragmentation of sample, is the best method for the identification of biological molecules. Previous studies have suggested alkaline salts as a suitable compounds for the transfer of sodium ion (Na + ) to amino acids and peptides to achieve their molecular ion in MALDI spectrum. In this study, the effect of sodium dodecyl sulfate (SDS) as Na + transfer matrix has been investigated for the first time in the MALDI of amino acids. In the first part of the experiment, the mass spectra of aluminum, silver, and brass alloy as repeller plates were recorded. The low number of background peaks in the desired regions of mass spectra of the plates showed that they could be suitable for the MALDI of amino acids. In the second part of the experiment, the amino acid mass spectrum of Phenylalanine (F) was recorded in the presence of SDS surfactant and NaF salt, separately using the aluminum, silver, and brass plates. The recorded spectra when SDS was used as Matrix showed the peaks of [F-H+2Na] + species for all metal plates, and [F+Na] + only for silver and brass plates. The recorded spectra using NaF as Matrix when Ag and Al were used as repeller plates, did not show the peak related to [F+Na] + species, while the peak of [F-H + 2Na] + species was seen in the spectrum recorded using Al plate. Separate tests on F in the presence of sodium sulfate and sodium octyl sulfate surfactant, revealed no peaks of the two major molecular ion species. So, the advantage of SDS in creating the peaks of [F + Na] + and [F-H + 2Na] + ions in the mass spectrum of F is mainly due to the presence of hydrocarbon chain in its structure. Similar performed experiments using SDS and NaF, separately on the silver repeller plate for Valine and Proline amino acids, has provided similar results. The use of SDS as the Na + transfer matrix for the alanine and tyrosine amino acids did not yield good results. In the other part of this thesis, the sodium affinity of the three amino acids in the presence of sodium ion and SDS molecule have been calculated using the density functional theory (DFT) method in the gas phase. The calculations showed the attachment of Na + to the amino acids in the gaseous phase was not valid and these processes were probably carried out in the solid phase and affected by the effects of metal surfaces. Finally, according to the results of this study, SDS surfactant can be introduced as a Na + transfer matrix for the MALDI of some amino acids.