Temporal percentage change in weight by DDVP after their opening in the experimental chamber. The black line shows change in weight from the initial 30.66 ± 0.59 g of DDVP strips (n =3) which is the result of gradual evaporation of the active ingredient in the strips. The dotted line represents the linear regression line that describes DDVP evaporation rate (data for the first day is excluded because of weight increase caused by initial moisture absorption from air into the porous matrix of the strip).