The interaction between Parafilm and four tranquilizers in their neutral phosphate buffer solutions resulted in various degrees of loss of the drugs from the solutions. The values of loss ranged from 15 to 34% for chlorpromazine and 8 to 42% for butaperazine at the initial concentration range of 2 to 20 mug/ml at room temperature (22 +/- 1 degree C). Under the same conditions, the values of loss from saliva for these two drugs were fairly constant; about 25% and 17%, respectively. For diazepam and chlordiazepoxide, the losses from the buffer solution were below 5%.