Jenny,

Yes, you can use 16 or 24 bit ADC/DAC with the 8052 family, in fact some of the derivatives of this family have them on board. One example is the ADuc834 from Analog Devices, but there are devices from Cygnal, Phillips, etc. The one pitfall that you will run into is that you will most likely not get 16 bits or 24 bits resolution, due to noise. Careful consideration of grounds( ground plane, thick ground traces, etc.) and the use of bypass capacitors is advised.

Regards,

Jacob