Arduino UNO analog input pins
The sample rate is nowhere close, neither in samples nor bits per cycle. The datasheet gives the conversion time for a single sample relative to the ADC clock as:

A normal conversion takes 13 ADC clock cycles. The first conversion after the ADC is switched on (ADEN in
ADCSRA is set) takes 25 ADC clock cycles in order to initialize the analog circuitry.

The ADC clock itself is taken from the system clock, with a prescaler ranging from /2 to /128, with the condition that the ADC clock ought to be no higher than 200 kHz. This yields a roughly 15 kSps sampling rate at best.