spectra acquired by means of the LIFT technique [36] were composed
from precursor ion peaks recorded at the above conditions
to which were added product ion spectra acquired by 500–2500
shots at the same laser frequency and 28% and 56% power, respectively.
A collision gas was not specially supplied. Four spectra of
each compound obtained at the combination of power of
20 + 28% and 40 + 56%, two spectra for the pair of powers, were
entered into the library. In these, most mass peaks were the same
for the unique compound with some variations of their relative
intensities. For example, there were variations of the [M+H]+ peak
intensity within the range of approximately 50–100%.
From seven standard compounds, MALDI product-ion spectra
were acquired for six ones. In the case of microcystins-LA, the signal
of poorly fragmenting [M+Na]+ ions was only observed.
The water-methanol extracts of the two bloom-forming cyanobacterial
strains of Microcystis aeruginosa 972 and 973 (see [37])
with microcystin concentration of