Characterization of hematology lysing reagents containing quaternary ammonium halides using fast-atom bombardment mass spectrometry.

Positive- and negative-ion fast-atom bombardment (FAB) mass spectrometry has been employed to characterize pure dodecyl-, tetradecyl- and hexadecyl-trimethylammonium chlorides and bromides, compounds of high interest as lysing agents in hematologic analyses. In parallel, the same approach has been used for some commercially available lysing reagent products. While in positive-ion FAB mass spectra the presence of the abundant ions corresponding to the intact quaternary ammonium cations (Q+) is accompanied by the presence of [Q2X]+ (X = Cl, Br) species, in the negative-ion mode cluster ions such as [QX2]- are the sole ionic species that are easily evident. The mechanism for the formation of [Q2X]+ and [QX2]- species has been studied and some suggested explanations are given.