I believe an analog delay can be introduced - purposeful propagation delay of sorts. I want to do it in the most efficient way, however.
First, set the ADC prescaler to as high as you can. For example, in AVRlib, you'll see:
#define ADC_PRESCALE_DIV128 0x07 ///< 0x07 -> CPU clk/128
Also, you can set up an interrupt that reads the ADC occasionally, while the rest of the time your processor is busy at work.