Stability of glutaraldehyde disinfectants during storage and use in hospitals

The problem of alkaline and acid glutaraldehyde disinfectants degradation (loss in active ingredients) during both extended shelf storage and continuous daily use under hospital practice was investigated. Glutaraldehyde disinfectants lose their potency due to three main types of reactions: aldol condensation, hydration-polymerization, and oxidation. The relative magnitude of each depends upon many variables, such as pH, dissolved gases content, and temperature. Room temperature aging studies of commercial potentiated acid glutaraldehyde (2% and 10% Sonacide) showed that the maximum loss in active ingredients is on the order of 7 per cent after 24 months. The newest type of stabilized alkaline glutaraldehyde (2% Cidex-7) loses 14 to 18 per cent of its active ingredient one month after buffer is added. Standing at room temperature, both alkaline and potentiated acid glutaraldehyde solutions generally drift towards lower pH. Several experiments and a literature search were conducted to assess the glutaraldehyde loss in alkaline and potentiated acid glutaraldehyde disinfectants under normal operating conditions in hospitals. Three independent studies showed that under continuous daily use in hospital buckets potentiated acid glutaraldehyde lasted twice as long as the alkaline glutaraldehyde formula. It was also noted that after weeks of continuous use the pH of both acid and alkaline formulas drifted towards neutrality. A six hospital study of potentiated acid glutaraldehyde in the Cidematic disinfecting machine showed that under a wide range of operating conditions it would take approximately four weeks of continuous daily use to reduce by half the concentration of active di-aldehyde.