DETERMINATION OF METHANOL IN AEROSOL PROD UCTS CONTAINING PROPELLANT

According to the official analytical method of methanol in commercial aerosol products, the concentration of methanol in their propelled sol ution was limited to less than 5%. The propelled solution was sampled by propelling aerosol into a flask for the evacuation of the propellan t only. There was the possibility of occurrence of errors due to flyin g nebulized methanol in the procedure of propelling, or due to the hig h volume of dissolving propellant in the propelled solution. In this p aper, after making some test aerosol products, the possibility of occu rrence of error was discussed. The recoveries of methanol in the test aerosol products containing the ratio of 5% methanol/ethanol solution and isobutane by weight of 5:5, 4:6, 3:7 were high yields ranging from 97.5 to 99.2%. But those of 2:8 and 1:9 were 94.4% and 80.3% respecti vely due to the flying nebulized methanol. The detective yield of meth anol in the propelled solution from the test aerosol products in the r atio of 3:7, after weighing the propelled solution by pouring it into a volumetric flask, with the propellant kept inside, was only 67.3%. T he problem of dissolving propellant was solved by freeing the propella nt while swinging the propelled solution flask on a water bath (20 deg rees C) within a tiny zeolite and weighing the propelled solution usin g a 1mm i.d. tip dropping pipet. As a result of this experiment, it is suggested that the determination of methanol by the official analytic al method may not be achieved in an aerosol containing high percentage of propellant.