Formula storage is one of the most tricky things about feeding a baby so I recommend purchasing a formula travel case and packing extra, empty bottles.
To properly store formula:

Feed your baby prepared formula immediately.
Immediately refrigerate prepared formula up to 24 hours.
Discard any extra formula after one hour because bacteria can grow VERY quickly.

If you are traveling, use the formula dispenser.

With three four Chinese infants dead, more than 6,000 children with kidney failure, and China’s major dairy producers testing positive for contamination of their milk products, the obvious question is –
would melamine find its way into US dairy and milk formula supplies?
Melamine is a chemical, a “trimer of cyanamide”, that is used to make plastics and fertilizers. Because of its high nitrogen content, melamine has been illegally used to increase protein content in otherwise water-down versions of liquid milk and infant milk formulas by the Chinese companies in question. Melamine is dangerous; it can cause kidney stones …read more