Titration of OH in H2SO4 and measurement of H2SO4 and MSA via proton exchange with NO3-. DMSO and DMSO2 are reacted with NH4+ ions. In all cases concentrations are determined by product/reactant ion ratios. Ion ratios are measured with quadrupole mass spectrometers.
OH measurements used to understand fast photooxidation chemistry; H2SO4 used to investigate particle nucleation; H2SO4 and MSA used to understand particle growth; DMSO and DMSO2 to investigate DMS oxidation process and its relation to particle production and growth.