I am using the adc to measure the voltage across a gas sensor that changes resistance as a function of gas concentration. The sensor which has resistance from 1k ohm to 750 k ohm and usually around 30k ohm (for normal gas concentrations) is in series with another resistor(38.4k ohms) to form a voltage divider. Now correct me if i am wrong but the output impedance of this circuit is usually higher than what the data sheet cites as being the highest impedance that you should have(10k ohms). My question is how can i assure that the adc reading is accurate? The solution needs to be low power and not take up much room. Can I just use a low adc clock frequency?