Sodium 5-oxo-DL-prolinate

Vapour pressure

Description of key information

Under the conditions of the study, the vapour pressure of the test material was determined to be < 8.4 x 10^-4 kPa at 25 °C.

Key value for chemical safety assessment

Vapour pressure:

0.001 Pa

at the temperature of:

25 °C

Additional information

This endpoint is addressed with two studies, one key and one supporting. The key study (Atwal, 2009) was performed under GLP conditions and in accordance with standardised guidelines. The study was assigned a reliability score of 1 in line with the principles for assessing data quality as defined by Klimisch (1997).

The vapour pressure of the test material was determined in a study conducted under GLP conditions in line with EU Method A.4, using a vapour pressure balance. Measurements were made at several temperatures and linear regression analysis used to calculate the vapour pressure at 25 °C. A sequence of five runs was started after a sample of the test material had been under vacuum for approximately 46 ¾ hours. Temperature and pressure readings were taken between 70 and 80 °C with a one hour dwell at 70 °C between runs.

No statistical analyses were performed because the balance readings were too low and variable for a line of best fit to have any meaning. Instead it was considered more appropriate to impose a regression slope on a chosen data point to provide an estimate of the maximum value for the vapour pressure at 25 °C. Run 5 was chosen because the sample had been under vacuum for the longest period prior to this run and so degassing would have been the most complete.

The reading at 79 °C (352.15 K) was chosen because this is the data point which gives the highest estimated vapour pressure at any given temperature when a slope of -1500 K is imposed upon it. The value of -1500 K is an in-house value and is the shallowest slope observed whilst determining the vapour pressure on a wide range of samples using the vapour pressure balance method. Extrapolation to 25 °C gave a vapour pressure of 8.244 x 10^-4Pa which has been taken as a maximum for this material.

Therefore, under the conditions of the study, the vapour pressure was determined to be < 8.4 x 10^-4Pa at 25 °C.

The supporting study (Savari, 2012c) was performed using the read across substance, sodium 5-oxo-L-prolinate. Read-across is considered to be suitable based on the structural similarities between the read across substance (sodium 5-oxo-L-prolinate) and the substance to be registered (sodium 5-oxo-DL-prolinate). As such the difference in isomeric forms of the substance is unlikely to affect the physico-chemical properties. The study was conducted under GLP conditions and in accordance with standardised guidelines. The study was assigned a reliability score of 2 in line with the principles for assessing data quality as defined by Klimisch (1997). Under the conditions of the study, the vapour pressure was determined to be 0.54 kPa at 20 °C and 0.68 kPa at 25 °C.