Extract of Boswellia serrata (Burseraceae) obtained from exudate by solvent extraction

Surface tension

Link to relevant study record(s)

Reference

Endpoint:

surface tension

Type of information:

experimental study

Adequacy of study:

key study

Study period:

11-18 June 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

The study was conducted according to an internationally recognised method, and under GLP. The substance is considered to be adequately characterised. Therefore full validation applies.

Qualifier:

according to guideline

Guideline:

OECD Guideline 115 (Surface Tension of Aqueous Solutions)

Version / remarks:

dated 27. July 1995

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method A.5 (Surface Tension)

Version / remarks:

dated 31 May 2008

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

GLP certificate (inspected on 15 to 16 November 2017 / signed on 15 May 2018)

Type of method:

plate method

Surface tension:

66.39 mN/m

Temp.:

20.5 °C

Conc.:

49.32 mg/L

Remarks on result:

other:

Remarks:

Result obtained from a 90% saturated solution prepared with a loading rate of 1g/L of test item and a shaking time to saturate the solution of 72h. Concentration of the test solution : 49.32 mg of test item/L (estimated based on analysis of dissolved organic carbon in the test solution).

Surface tension:

68.28 mN/m

Temp.:

20.3 °C

Conc.:

14.7 mg/L

Remarks on result:

other:

Remarks:

Result obatined from a 90% saturated solution prepared with a loading rate of 1g/L of test item and a shaking time to saturate the solution of 7 days. Concentration of the test solution : 15.49 mg of test item/L (first determination) and 14.7 mg of test item/L (second determination) (estimated based on analysis of dissolved organic carbon in the test solution).

Key result

Surface tension:

67.33 mN/m

Temp.:

20.4 °C

Remarks on result:

other: Mean of results obtained from two 90% saturated solutions (loading rate of 1g/L and shaking times to saturate the solution of 72h and 7 days respectively. Concentration of test solutions: 15.49 - 49.32 mg of test item/L (estimated based on DOC analysis).

Table 4.10.1: Results obtained on replicate one (after shaking 72h to saturate the solution used)

Test	Mass (g)	Surface tension, Mean ± SD (mN/m)	Temperature (°C)
Negative control	0.2975 -0.2986	72.67 ± 0.07	20.4
Test substance: First series	0.2717 -0.2739	66.39 ± 0.16	20.5
Test substance: Second series (verification)	0.2767 -0.2792	67.71 ± 0.17	20.1

Table 4.10.2: Results obtained on replicate two (after shaking 7 days to saturate the solution used)

Test	Mass (g)	Surface tension, Mean ± SD (mN/m)	Temperature (°C)
Negative control	0.2975 -0.2983	72.64 ± 0.05	20.6
Test substance: First series	0.2783 -0.2822	68.28 ± 0.26	20.3
Test substance: Second series (verification)	0.2788 -0.2813	68.17 ± 0.18	19.9 -20.0

The surface tension of the negative control was determined with 72.67 mN/m at 20.4°C and 72.64 mN/m at 20.6°C, therefore showing a difference of 0.01% from the stated literature value, calculated from the equation cited in the « online calculation of the Surface Tension of Ordinary Water Substance » page (http://twt.mpei.ru/MCS/Worksheets/iapws/Surf-H2O.xmcd): 72.68 mN/m at 20.4°C and 72.64 mN/m at 20.3°C. The difference lies within the accepted range of 1% deviation from literature value.

For both replicates, detailed findings of each step are provided in the study report. Values ranging from 66.28 mN/m to 68.11 mN/m (replicate one) and from 67.89 mN/m to 68.84 mN/m (replicate two) were recorded showing no significant variations. The values of the single determinations show no significant difference, i.e. the difference between the mean values obtained in both measurement series was 1.99 % for replicate one and 0.16% for replicate two. Also the difference between the mean values obtained with the two replicates was 2.85% laying within the criterion validity of 5%.

Therefore,no significant dependence on time was observed.

Results of TOC analysis of the filtrated test solutions 90%:

TOC analysis of the filtrated test solutions was performed using the carbon analyser TOC after monthly calibration and quality control after every start.

Table 4.10.3 Estimation of the concentration of the test item in the 90% saturated test solution (based on analysis of dissolved organic carbon in the test solutions) - Results of TOC analyses

Time	TOC value in mg/L (=DOC)	C content in %w/w*	Concentration of 90% test solution in mg of test item/L (estimated)
After 72h	34.99	70.94	49.32
After 7 days	10.99	70.94	15.49
After 7 days (checking)	10.43	70.94	14.70

*determined by elemental analysis, performed under non-GLP conditions

As the DOC values of replicate one (after 72 h) and replicate two (after seven days) were significantly different an additional DOC measurement of replicate two was performed resulting in a concentration, which confirmed the first result obtained on replicate two.

Conclusions:

The surface tension of aqueous solutions of the test item was determined as 67.33 mN/m at 20.4 °C (mean of two determinations obtained from two 90% saturated solutions prepared with a loading rate of 1g/L of test item and two times of shaking to saturate the solution of 72h and 7 days respectively)
Concentration of test solutions : between 14.70 and 49.32 mg of test item/L (estimated based on analysis of dissolved organic carbon in the test solutions).
According to EU A.5 criteria, as the result is above the threshold value of 60 mN/m, the substance is considered to have NO surface active potential under the experimental conditions.

Executive summary:

The surface tension of an aqueous solution of test item was determined according to EU method A.5 and OECD 115 under GLP using the plate method.

Two 90% saturated test solutions were prepared (replicate one and replicate two). They are obtained from aqueous solutions of test item prepared with a loading rate of 1.00 g test item/L, shaked for 72h (replicate one) and for seven days (replicate two).

The determination of surface tension (and verification) was conducted on each replicate.

The first determination was determined on replicate one, as 66.39 ± 0.16 mN/m at 20.5 °C. After 61 minutes, the verification was performed. No significant changes and thus no significant dependence on time was observed.

The second determination was determined on replicate two as 68.28 ± 0.26 mN/m at 20.3 °C. After 65 minutes, the verification was performed. No significant changes and thus no significant dependence on time was observed.

The difference of surface tension between the two determinations (after 72h and after seven days), calculated as 2.85%, laid within the criterion validity of 5%. Therefore, no significant dependence on time was observed.

 

As these values were higher than 60 mN/m, the test item was classified as not surface active substance.

The surface tension of the negative control laid within the accepted range.

Note that the concentration of the test item in the 90% saturated test solutions was determined (based on analysis of dissolved organic carbon in the test solution) to be 49.32 mg test item/L for the replicate one and 15.49 mg test item/L for the replicate two. This latest value was confirmed by an additional DOC measurement resulting in a concentration of 14.70 mg test item/L.

Considering the significant difference between concentrations estimated in replicate one and two, no key value for concentration of the test solution has been retained.

Only a range of estimated concentrations can be stated : between 14.70 and 49.32 mg of test item/L .

This is considered as not critical considering that a similar surface tension was obtained for both test solutions.

 

Description of key information

The surface tension of aqueous solutions of the test item was determined as 67.33 mN/m at 20.4 °C (mean of two determinations obtained from two 90% saturated solutions prepared with a loading rate of 1g/L of test item and two shaking times to saturate the solution of 72h and 7 days respectively)

Concentration of test solutions :  between 14.70 and 49.32 mg of test item/L (estimated based on analysis of dissolved organic carbon in the test solutions).

According to EU A5 criteria, as the result is above the threshold value of 60 mN/m, the substance is considered to have NO surface-active potential under the experimental conditions.

Key value for chemical safety assessment

Surface tension:

67.33

Additional information

A fully reliable experimental study, conducted according to a recognized OECD/EU method (plate method) and under GLP, is available.

It is considered as a key study.