Have a yellow cast to hair after bkt

is there a safe sodium free shampoo like blue shampoo to remove this yellow cast?  I have not washed yet after the initial treatment and I called Rejuvenol and asked what to do.  They recomended that I leave the conditioner on for 15 min after the first wash and that this shade of yellow will go away.  Still concerned though.  Inside lighting it looks fine, but in the natural light outside I see it more yellowy then gold.