Electrospray mass spectrometry of recombinant growth hormones

Abstract

The electrospray mass spectra of several standard proteins were recorded and their molecular weights determined. These were compared to Literature values obtained by other laboratories. The agreement was quite good. Seven recombinant growth hormones were then investigated by this technique. The determined molecular weights were in agreement with the theoretical values. Differentiation between six of the seven analogs could be made on the basis of the molecular weight determinations. Two of these analogs differed in molecular weight by only 1 Da and the accuracy of the mass measurements was not sufficient for distinguishing these two homologous proteins. The influence of solvent on the mass accuracy determinations was studied. It appears that solvents form clusters with the proteins in the electrospray ionization method. These clusters broaden the peaks corresponding to the multiply charged ions of the proteins and make the determination of centroids more difficult.

Use of protic and aprotic solvents of high volatility as matrices in analytical low‐temperature fast‐atom bombardment mass spectrometry

“…Initially, glycerol was the only matrix used 5 but before long other organic solvents of low volatility were found to yield improved spectra; among them 3-nitrobenzyl alcohol (3-NBA) 6-8 2nitrophenyl octyl ether (2-NPOE), 6,9 paraffin, [10][11][12] sulpholane, [13][14][15] concentrated sulfuric acid 16 and others. 9,17,18 Since that time several reviews on the matrix aspect [19][20][21][22][23] and on the processes of desorption and ion formation [24][25][26] under FAB conditions have appeared. It is commonly accepted that a good matrix for FAB-MS has to meet the following requirements: 19,22 1) The samples must be soluble in the matrix, otherwise addition of co-solvents like dimethyl formamide (DMF) or dimethyl sulphoxide (DMSO) becomes necessary.…”

“…9,17,18 Since that time several reviews on the matrix aspect [19][20][21][22][23] and on the processes of desorption and ion formation [24][25][26] under FAB conditions have appeared. It is commonly accepted that a good matrix for FAB-MS has to meet the following requirements: 19,22 1) The samples must be soluble in the matrix, otherwise addition of co-solvents like dimethyl formamide (DMF) or dimethyl sulphoxide (DMSO) becomes necessary. 2) Only low vapor pressure solvents can be easily used.…”