Both 100-mv/g and 500-mv/g ICP/IEPE accelerometers have rated frequency response well below 2-Hz (for example CTC). Obviously the more sensitive one produces 5x higher voltage for the same acceleration level (g), and it generally would be a better choice. Some measurement issues include noise floor (spectrum), background vibrations (spectrum), cable vibrations, HP filter setting of analyzer, signal integration for velocity/displacement (may not be possible). Another type of low frequency accelerometer is the MEMS that also has DC response, but check the sensitivity and noise floor specifications as compared to the ICP/IEPE type. I have also used a proximity probe, LVDT and lanyard potentiometer, and geophone sensors for special low frequency measurements. What are you trying to measure?
Walt