Yellow stains around collars

[Cally]

DH has started wearing business shirts to work more. He has a few nice white ones, but after only wearing them a couple of times they have started to get that yellowing around the collar.

We've tried various sprays, soaking them, rubbing them with a Napisan paste and nothing seems to work. I gave them all a big soak over night in Napisan and they spent yesterday in the sun and they're still yellow.

He really likes the white shirt look, but I'm tempted to just say coloured shirts only for work and save the white ones for formal occasions.

Any other ideas for getting those stains out??

[feeb]

Same issues her not that DH has many whites tends to mainly have coloured, but also sweat stains.

Not sure either how to remove.