The phase difference between V and I in pure inductance (zero resistance) in an AC circuit is

Purely inductive circuits are those with just one inductance of no resistance
In the circuit, 

The alternating emf is,

$e=e_o\sin \omega t$

Current in the inductive circuit is,

$I=I_o\sin \left(\omega t-\frac{\pi }{2}\right)$

Since, It is clear that the voltage lead the current by $\raisebox{1ex}{$\mathrm{\pi }$}\!\left/ \!\raisebox{-1ex}{$2$}\right.$ or $90°$.