Why have my DDs school blouses gone lilac?

[LordOfTheFlies]

I bought DD some Tesco short sleeved school blouses 2 weeks ago.She had some this school year and really liked them.
I wash whites by themselves and with 2 DCs, DHs white shirts,DS karate suit and white hand towels I do a couple of white washes a week.
I use Ariel bio or Daz. + Ariel stain remover.
Its just these blouses which have gone lilac (not a Daz 'blue-white) Not noticeable on their own, but if next to other whites you can see it.

Anyone else had this?

Funny you should say this as a couple of years ago I bought a pack of 3 white polo shirts.

They like you say looked white, but when you put them next to something else white, they had a pinky tinge. This was straight out the pack before I'd washed them or anything. Are you sure you didn't just notice it when you first bought them?

I took them back as thought my Ds wouldn't appreciated turning up in a pink shirt

I suppose they could have reacted to the powder in some way? Do you use an in-wash stain remover normally, I have had trouble with those occasionally (but not lilac colouring, I have to say).

Sorry, mis-read - I see that you do use the in-wash stain remover - might be that then. If it is that, then it will never come out - but you could try bleaching the shirts, or using a whitener, or one of those "colour accident" removers.