[Reutilization of paraformaldehyde tablets: assessment of their sterilizing effect]

The sterilizing activity of reused Paraformaldehyde tablets was assessed by microbiologic monitoring according to the Association of Official Analytical Chemists (AOAC) technic required in Brazil to register this class of sanitizing substances into the Health Ministry. Previous to the microbiologic tests, physical-chemscs assays were done through iodine titration according to the Society of Japanese Pharmacopoeia. It was possible, than, to draw a graphic showing a curve of the gaseous formaldehyde concentration discharged, at each sterilization cycle in relation to the number of reuse of the paraformaldehyde tablets. Through this graphic it was possible to chose the adequate moment to make the microbiologic analysis. After 12 cycles, the some group of the paraformaldehyde tablets kept the sterilizing activity at 3% concentration (3 g/100 cm3), at 50 degrees C, for 4 hours of exposition time with great relative humidity.