Yes, Arizona passed a law to allow taxpayers to subtract 25% of their long term capital gains on investments acquired after 12/31/2011.
If the assets you sold were purchased before 12/31/2011, they do not qualify for this treatment.
Here is the line instruction that applies to this deduction:
"You may subtract 25% (.25) of any net long-term capital gain included in your federal adjusted gross income that is derived from an investment in an asset acquired after December 31, 2011." -AZDOR
The instruction book has a worksheet to calculate the deduction on page 30, but there is no advice for how to determine the amount of your investments acquired after that date.
It would probably be best to work with your statements or your broker to determine how much of your funds were acquired before December 31, 2011.
Click here to see the AZ 140 booklet.