The effect of common nucleic acid stains on the composition of particulate organic matter as determined by direct temperature-resolved mass spectrometry and pyrolysis-gas chromatography-mass spectrometry

The nucleic acid stains DAPI and SYTO-13 were used to stain particulate organic matter (POM) samples from the lower Chesapeake Bay and from a culture of Synechococcus (CCMP 837). Cell counts determined using each stain were compared as was the effect of each stain on the organic matter composition of the POM. Both stains yield similar cell counts, though SYTO-13 counts are lower than DAPI counts for each Chesapeake Bay sample site. The stains do not significantly affect organic matter composition as determined using direct temperature-resolved mass spectrometry (DT-MS) and pyrolysis-gas chromatography-mass spectrometry (PyGCMS). This means that either stain could be used for cell identification within samples prior to molecular-level characterization of the same samples.