Hi Sasha,
To be able to reduce U-Pb apatite ages correctly, you need a suitable apatite standard. Where suitable means with enough U to generate radiogenic Pb, and old enough to be able to distinguish radiogenic from common Pb. NIST is a glass and thus does not match apatite matrix, also only has common Pb in it. And Durango is too young (ca. 31 Ma) and only has around 9-12 ppm U. So won't work either. You need a different standard. As far as I know most people dealing with apatite UPs uses Madagascar apatite, which is around 1075 Ma (is memory does not fail me...).
Cheers
Luigi