Patent ID: 6852856

Claim:
A method of preserving a quaternary ammonium salt having a purity equal to or less than 99.8%, the quaternary ammonium salt being represented by the following general formula (I), wherein R 1 is an alkyl group having 1 to 4 carbon atoms or an aryl group having 6 to 8 carbon atoms, R 2 is an alkyl group having 1 to 4 carbon atoms, and X is a halogen atom, said purity of quaternary ammonium salt being determined by chromatographic analysis peak area % measured by using a high-performance liquid chromatography and wherein water is not an impurity, the method comprising the steps of: preparing a hydrous quaternary ammonium salt consisting of 60 to 99% by weight of said quaternary ammonium salt and 40 to 1% by weight of water by adjusting a content of water in the salt, and preserving the thus obtained hydrous quaternary ammonium salt.