Sodium hydroxide is used in conjuction with either a pH meter or phenolphthalein indicator when testing for total acidity in juice or wine. It should be used with either a graduated dropper or burette or a graduated syringe to ensure accuracy in testing. This is a caustic material which can burn skin and tissue and should be used with caution. It must be kept in a closed container when not being used and will only last about one year after being opened. It will lose strength over time and should be replaced anually.