One lot of meprobamate raw material and 28 lots of tablets were examined for impurities by TLC. All lots contained di-(2-methyl-2-propyl-3-carbamoyloxypropyl) carbonate (V) at levels that ranged between 0.1 and 1.0% of the total drug content. Nine lots also contained low levels of a second impurity (approximately 0.1%), and one of these lots contained a third impurity (approximately 0.1%), neither