I currently do anhydrous skin care and want to break into aqueous sensitive skin facial care. Something simple, like a toner. I have seen a few on the market; is it possible to make a toner using alcohol free witch hazel, hydrosol, seaweed extracts, cucumber extracts, vitamins, and citric acid without preservation? Is citric acid stable enough to keep a product safe for a year? Is it the best choice for sensitive skin?If not, are there other acidifiers that would work effectively for those who are sensitive?