English Abstract This report describes the results of an investigation
into the utility of electrospray ionization - mass spectrometry (ESI-MS) for
the determination of the molecular mass of small proteins (up to 17 kDa).
The molecular mass of four pure proteins, was determined by ESI-MS. From
the known molecular mass of the proteins, the accuracy of the method can be
estimated. Two methods were applied to calculate the molecular mass from
the acquired ESI mass spectra. In terms of accuracy and precision of the
measured molecular mass, the two methods were almost equal. The results of
this investigation show that an accuracy of about 0.01% and precision of
0.006% can be achieved. The acquisition of the ESI mass spectro required
10 pmol of protein.