by
lmh » Mon Feb 29, 2016 12:00 pm
I think you need to try these out for yourself; ask the manufacturers to provide test data based on a sample that you supply to all three (and do try to specify the method in a way that means you get comparable results). For an instrument of this value, they should be happy to oblige. It's impossible to say globally that one instrument is more sensitive than another, because sensitivity depends so much on the target compound (one rep once joked that his company had the best reserpine-measuring machine currently available).
All three instruments will do the job. Differences between the top-end instruments of the good manufacturers tend to be quite small (if they weren't, the worse companies would have gone out of business). Your method, and how you prepare your samples and how you use the instrument will have a far greater effect on sensitivity than the choice of instrument (but of course you want to get the best you can!).
About software: again, all three manufacturers have software that includes all the functionality you need, but they have very different philosophies. The best thing would be to get someone from each company to demonstrate the software and decide which you like best. It makes a big difference having something you feel happy with, and that fits the way your lab prefers to work.