EMI sensitivity in zero-drift op-amps

No, but I have seen DC offsets that were a function of the capacitance seen by the two inputs. Some sort of charge injection thing, several microvolts of offset.

I don't know, as I put on RF filtering as a matter of course when desiging a board for measuring microvolt signals, and the zero-drift opamps that I prefer are only available in MSOP so I normally make a board if I use them. Even when I make the board with a scalpel on blank FR4, I still include the RF filtering parts.

I have seen RF rectification plenty of times on veroboard amplifiers with non-zero-drift ordinary bipolar op-amps. It is something that you are likely to care about when measuring microvolt signals which is the same situation where you might buy a zero-drift op-amp, so EMI-hardness may be offered on newer op-amps just because it is useful in their typical applications, not necessarily because they are worse than other op-amps.

I have found it useful to get a RF signal generator, plug in a piece of coaxial cable and strip the end, and connect e.g. a 5.6pF capacitor in series with the inner conductor, and go around the amplifier circuit blasting each external IO terminal with e.g. 0dBm or +10dBm at 1GHz (or try a few frequencies if you have time), and measure how much the DC output voltage changes with RF on and off. On one RTD amplifier I was able to reduce the sensitivity to RF quite a lot by adding an adhesive copper tape ground plane and a bunch of surface mount filtering capacitors, even though the amplifier was still built on stripboard.

Chris