Glutaral

Hydrolysis

Description of key information

In contact with water glutaraldehyde will hydrolyse slowly.

Additional information

Hydrolysis of 14C-glutaraldehyde was investigated in a test performed according to US EPA Guideline subdivision N 161-1 at pH 5, 7, and 9 in sterile buffer solutions at 25°C and 70°C (CHMR 1991). The test solutions were incubated for 30 days in the dark. Because of the rapid hydrolysis of 14C-GA at 70 °C in pH 9 buffered solutions an additional experiment was conducted for 7 hours at 70 °C and at a test concentration of 142.20 ppm. At a temperature of 70 °C,the half-life times for glutaraldehyde were 53 days, 6.5 days and 0.23 days respectively at pH 5, 7 and 9. Hydrolysis relevant products were found at all tested pH values. In addition to the parent compound glutaraldehyde, the products obtained from hydrolysis were identified in the pH 9 buffered samples by means of gas chromatography/mass spectrometry (CG-MS) as delta-valerolactone and as the two glutaraldehyde condensation isomers, cycloocta 1,5- diene 1,5-dialdehyde and cycloocta 1,4-diene 2,4-dialdehyde. At a temperature of 25 °C, the half-life times for glutaraldehyde were 628 days, 394 days and 63.8 days respectively at pH 5, 7 and 9.A relevant hydrolysis product (i.e. >= 10% of applied radioactivity) was identified at pH 9 as delta-valerolactone whereas no hydrolysis products >= 10% were seen during the 30 day study at pH 5 and pH 7. Glutaraldehyde was shown to be very stable at pH 5 and 7 at 25 °C, with a half-life time > 390 days.

Hydrolysis of glutaraldehyde at pH 4, 7 and 9 was tested according to Directive 92/69/EEC, C.7 for 165 h (BASF AG 94L00263). At pH values of 4 and 7 as well as in water (pH 4.58) degradation of the test substance was less than 10 % over 5 days at a temperature of 50 °C, indicating that under these conditions the test substance was stable against hydrolysis. At pH 9 a reduction in test substance concentration was observed, the degradation of the test substance did not follow a pseudo 1 order reaction. At pH 9, oligomerized products of glutaraldehyde were reported as degradation products. However, these products were no hydrolysis products but resulted from condensation of aldehyde groups. A further study is available, which had been conducted according to the OECD TG 111 (BASF AG 0/93/9932).The amount of glutaraldehyde was determined photometrically by the thiobarbituric acid following storage at 50 °C under exclusion of oxygen during 5 days, at pH 4, pH 7 and pH 9. At pH 4 and 7, the decrease in GA concentration was < 10%, and at pH 9, the decomposition reached 76%. Thus, glutaraldehyde was hydrolytically stable at pH 4 and pH 7, and decomposed at pH 9. This was further in accordance with the results of another study (ABC Lab Inc. 32738) conducted acccording to the US EPA Guideline subdivision N 161-1, which had shown that hydrolysis of glutaraldehyde was minimal at pH 7 but significant at pH 9, with a half-life of 78 and 19 days, respectively.

In conclusion, glutaraldehyde was found to be stable against abiotic hydrolysis under relevant environmental conditions.