Soybean meal, protein extn. residue

Surface tension

Link to relevant study record(s)

Reference

Endpoint:

surface tension

Type of information:

experimental study

Adequacy of study:

key study

Study period:

04 January 2018 to 30 March 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 115 (Surface Tension of Aqueous Solutions)

Version / remarks:

1995

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method A.5 (Surface Tension)

Version / remarks:

2008

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

ring method

Key result

Surface tension:

53.3 mN/m

Temp.:

20 °C

Conc.:

1 g/L

Table 2: Readings, Times and Temperatures for the Sample Solutions

Age of Solution (min)	Reading (mN/m)	Temperature (°C)
Sample 1
80	53.0	20.0
89	54.5	20.0
98	53.0	20.0
107	53.5	20.0
116	53.5	20.0
124	53.0	20.0
134	53.5	20.0
Sample 2
146	55.5	20.0
153	54.0	20.0
161	53.0	20.0
169	53.0	20.0
177	53.5	20.0
185	53.5	20.0
194	53.5	20.0

 

Mean Sample 1 result: 53.3 mN/m (last 5 readings)

pH of Sample 1: 5.7

Mean Sample 2 result: 53.3 mN/m (last 5 readings)

pH of Sample 2: 5.7

Mean result : 53.3 mN/m

Overall temperature: 20.0 ± 0.5 °C

 

Discussion

- On removal from the 20 °C equilibration, the samples were assessed as cloudy solutions. After filtration, the samples were clear, pale yellow solutions, which exhibited no Tyndall beam effect.

- According to criteria stated in EC Method A.5, substances showing a surface tension lower than 60 mN/m under the conditions of this method should be regarded as being surface-active.

- As the test material showed loading rate dependency in the water solubility endpoint test, it was considered appropriate to prepare solutions of test material in water at a loading rate of 1.1 g/L and then dilute to 90 %, to give a “nominal” test material concentration of 1.0 g/L. However, as only 41 % of the loaded test material would have dissolved at a loading rate of 1.1 g/L, the test material concentration in the (90 % diluted) test solutions would be closer to 0.4 gTOC/L than 1.0 g/L.

- That said, the surface tension results indicate that the test material is surface-active, and as such, a higher test material concentration of 1.0 g/L would also indicate surface-activity.

Conclusions:

Under the conditions of this study, the surface tension of the test material was 53.3 mN/m at 20 °C and was therefore considered to be surface-active.

Executive summary:

The surface tension of the test material was investigated in accordance with the standardised guidelines OECD 115 and EU Method A.5, under GLP conditions.

The balance and ring assembly used to measure the surface tension of the test material give a direct reading of surface tension that is within the required accuracy (± 0.5 mN/m).

On removal from the 20 °C equilibration, the samples were assessed as cloudy solutions. After filtration, the samples were clear, pale yellow solutions, which exhibited no Tyndall beam effect.

According to criteria stated in EC Method A.5, substances showing a surface tension lower than 60 mN/m under the conditions of this method should be regarded as being surface-active. The mean result for the test material surface tension was 53.3 mN/m. It is likely that only 41 % of the loaded test material would have dissolved at a loading rate of 1.1 g/L and so the test material concentration in the (90 % diluted) test solutions would be closer to 0.4 gTOC/L than 1.0 g/L, however a higher test material concentration of 1.0 g/L would still indicate surface-activity

Under the conditions of this study, the surface tension of the test material was 53.3 mN/m at 20 °C and was therefore considered to be surface-active.

Description of key information

Under the conditions of this study, the test material was considered to be surface-active.

Key value for chemical safety assessment

Surface tension:

53.3

in mN/m at 20°C and concentration in mg/L:

1 000

Additional information

The surface tension of the test material was investigated in accordance with the standardised guidelines OECD 115 and EU Method A.5, under GLP conditions. The study was awarded a reliability score of 1 in accordance with the criteria set forth by Klimisch et al. (1997).

The balance and ring assembly used to measure the surface tension of the test material give a direct reading of surface tension that is within the required accuracy (± 0.5 mN/m).

On removal from the 20 °C equilibration, the samples were assessed as cloudy solutions. After filtration, the samples were clear, pale yellow solutions, which exhibited no Tyndall beam effect.

According to criteria stated in EC Method A.5, substances showing a surface tension lower than 60 mN/m under the conditions of this method should be regarded as being surface-active. The mean result for the test material surface tension was 53.3 mN/m. It is likely that only 41 % of the loaded test material would have dissolved at a loading rate of 1.1 g/L and so the test material concentration in the (90 % diluted) test solutions would be closer to 0.4 gTOC/L than 1.0 g/L, however a higher test material concentration of 1.0 g/L would still indicate surface-activity

Under the conditions of this study, the surface tension of the test material was 53.3 mN/m at 20 °C and was therefore considered to be surface-active.