changing ADC sampling frequency in Arduino Duemilanove

Hey guys, I'm using Arduino Duemilaove and I have a doubt in ADC in it. What is the sampling frequency of ADC and also can it be dynamic?

What is the sampling frequency of ADC

As often as you call analogRead().

and also can it be dynamic?

That depends on what "it" refers to. The ADC can read dynamic signals. It will give a new value each time you call analogRead().

You can call AnalogRead() about 8000 times per second, however if you accept more noise (less bits) you can tune some registers.

read all about it here - http://www.microsmart.co.za/technical/2014/03/01/advanced-arduino-adc/