Concept of effective mass and hidden mass for calculation of mobility of organic anions and peptides.
The concept presented for the calculation of electrophoretic mobility is based on three assumptions: (1) the molecular mass M can be treated as composed of effective mass E and hidden mass H, M = E+H; (2) the mobility u is proportional to the charge Z and inversely proportional to the effective mass to the power 2/3; and (3) both E and H are additive functions of composition. Butyric acid was chosen as a standard fulfilling the condition M = E, H = 0, resulting in the equation u = 668ZE-2/3 x 10(-5) cm2 s-1 V-1. The suggested approach involves the summation of all special contributions to the hidden mass and calculation of the mobility from the effective mass E = M - sigma H. The total hidden mass involves values dependent on hydrocarbon structure, H alpha, dependent on functional groups, H beta, and contributions of certain subunits such as amino acids in peptides, Hr. The H alpha contributions for aliphatic compounds can be expressed as a function of the methylene (together with CH3 and CH but with the exception of CHOH chains) group content in the molecule. H alpha for aromatic compounds depends on the nature of the aromatic ring. The special contributions were derived from the mobilities of about 200 compounds. Mobilities calculated by the suggested approach indicate an average relative error of +/- 1.5% for organic acids and +/- 0.8% for peptides.
Wroński
M
M
Department of Chemical Technology and Environmental Protection, University of Lódź, Poland.
D000595:Amino Acid Sequence; D000838:Anions / Q000737:chemistry*; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D004586:Electrophoresis; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010455:Peptides / Q000737:chemistry*; D012997:Solvents
D000838:Anions; D010455:Peptides; D012997:Solvents