LMC660: Voltage on + input when floating

I am using one LMC660 to measure 4 different voltage levels. I have it wired as 4 different non-inverting buffers that then go into an ADC. I am seeing that when the +Input is left floating that the output of the opamp goes up ~2.2V. When I probe the +Input with a multimeter or an oscilloscope, the voltage goes away. The issue I have is that one of the opamps is used to read from a pH probe. Those have very high input impedance(>100MOhm). 

My question is, How can I get rid of that voltage in the +Input without affecting the reading from the pH probe. As of now, the pH signal is not strong enough to drive the +Input property.

Below is a snippet

Thanks