The invention relates to a process for producing an ammonium salt composition. The process comprises the step of providing a process stream comprising sulfuric acid, methylene dichloride, and a tertiary amine or a precursor thereof. The process further comprises the step of contacting the process stream with ammonia to form a product stream and a waste stream. The product stream comprises the ammonium salt and the waste stream comprises water, methylene dichloride, ammonia, and the tertiary amine. The process further comprises the step of deriving from the waste stream an off gas stream comprising ammonia and a first amount of methylene dichloride. The process also comprises the step of contacting at least a portion of the off gas stream or a derivative thereof with an adsorbent to separate at least a portion of the off gas into a methylene dichloride stream comprising methylene dichloride.