In the interests of avoiding duplication, see my posts (Edit: and Kate's response) on:
http://www.rootschat.com/forum/index.php?topic=243959The 1840 marriage/banns entries are in Old Machar, Aberdeenshire and in St Nicholas, parish of Aberdeen, Aberdeenshire.
Census entries give Ann's approximate birthdate as 1813 and birthplace as Aberdeen.
A possible baptism might be Ann PITTENDREACH, father James, 1814 - at St Nicholas in the parish of Aberdeen, Aberdeenshire.
Kate, I hope you view the marriage/banns entries and the baptism and let us know if they are any help.
Apparently the WHYTE family moved to England so, assuming Ann died there, death cert would not help 
Edit: Apparently it was a son John who moved south. So Kate might well find Ann's death on SP

Further edit: Seems to be there - Ann WHYTE, other name PITTENDRICH, year 1877, age 65.
JAP