Pepper (Piper), P. nigrum, ext.

Surface tension

Link to relevant study record(s)

Reference

Endpoint:

surface tension

Type of information:

experimental study

Adequacy of study:

key study

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)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method A.5 (Surface Tension)

Deviations:

no

Principles of method if other than guideline:

Not applicable

GLP compliance:

yes (incl. QA statement)

Remarks:

inspected on 13 and 14 October 2014 / signed on 08 April 2015

Type of method:

plate method

Key result

Surface tension:

61.13 mN/m

Temp.:

19.9 °C

Conc.:

12.64 mg/L

Remarks on result:

other: The concentration of the test item in the 90% saturated test solution was determined with 12.64 mg test item/L (based on analysis of dissolved organic carbon in the test solution).

Findings - Main Test

The test item solution was held at constant temperature (20.0 ± 0.5 °C). 59 minutes after conclusion of the first measurement series, a second measurement series was performed for verification purposes.

Table 1: Measured Values Test Item First Series

Measurement	Time	Mass	Surface Tension	Temperature
No	s	g	mN/m	°C
1	2.9	0.2458	59.96	19.9
2	5.9	0.2514	61.33	19.9
3	8.9	0.2513	61.30	19.9
4	11.9	0.2511	61.25	19.9
5	14.9	0.2513	61.30	19.9
6	17.9	0.2511	61.25	19.9
7	20.9	0.2510	61.23	19.9
8	23.9	0.2512	61.28	19.9
9	26.9	0.2507	61.16	19.9
10	29.9	0.2508	61.18	19.9
Mean			61.13
Standard Deviation			0.41

Table 2: Measured Values Test Item Second Series

Measurement	Time	Mass	Surface Tension	Temperature
No	s	g	mN/m	°C
1	2.9	0.2484	60.60	20.1
2	5.8	0.2528	61.67	20.2
3	8.9	0.2526	61.62	20.2
4	11.8	0.2526	61.62	20.1
5	14.9	0.2519	61.45	20.1
6	17.8	0.2523	61.55	20.2
7	20.9	0.2524	61.57	20.2
8	23.8	0.2521	61.50	20.2
9	26.9	0.2523	61.55	20.2
10	29.8	0.2525	61.60	20.2
Mean			61.47
Standard Deviation			0.31

After the first and the second measurement series, the difference between mean values was less than 5%. Therefore no additional measurement series was required.

Analytical Determinations   

TOC analysis of the filtrated test solution was performed using the carbon analyser TOC multi N/C 2100S, Analytik Jena. The test solution was measured in triplicate. The carbon analyser was calibrated with freshly prepared reference solutions containing potassium hydrogen phthalate (TC), sodium hydrogen carbonate and sodium carbonate (IC) every month.After every start, quality control samples were measured.

A value of 10.88 mg org. carbon/L was obtained, and the concentration of the test item was calculated from the measured DOC and the stated carbon content.The calibration data is presented in chapter15page18.

The carbon content in the test item had been determined under non-GLP-conditions in the laboratory Mikroanalytisches Labor Pascher (D-53424 Remagen) with 86.05 %w/w.

The concentration was therefore determined with 12.64 mg test item/L.

Results

During the specified period of time, no relevant changes in the surface tension were detected. Values ranging from 59.96 mN/m to 61.67 mN/m were recorded showing no significant variations. The values of the single determinations show no significant difference (less than 5 % between mean values of the two measurement series).

Only one value of twenty values was just below 60 mN/m. Therefore, the determined surface tension of the test item can be classified as not surface active.

Validity

Literature value for the surface tension of H₂O at 19.0 °C: 72.90 mN/m (taken from Vargaftik et al., “International Tables of the Surface Tension of Water”, J. Phys. Chem. Ref. Data 12, 817, 1983).

The surface tension of the negative control was determined with 73.01 mN/m at 18.9 °C, therefore showing a difference of 0.15% from the stated literature value. The difference lies within the accepted range of 1% deviation from literature value.

The values of the single determinations show no relevant difference (0.56% between mean values of the two measurement series). Only one measured value lay just below the threshold for surface tension which is stated in the guidelines. All other values lay above the threshold for surface tension which is stated in the guidelines.

The surface tension of the negative control was determined with a difference of 0.15 % from the stated literature value.

Therefore, the result of the test is considered valid and the test item is classified as “not surface active” in a concentration of 12.64 mg/L(i.e. in a solution at 90% saturation obtained from an aqueous solution prepared with 1g/L of test item slow-stirred for 72h).

Conclusions:

The surface tension of an aqueous solution of the test item was determined as 61.13 ± 0.41 mN/m at 19.9 °C. As all measured values were higher than 60 mN/m, the test item is classified as not surface active.

Executive summary:

The surface tension of test item was determined according to EU method A.5 and OECD 115.

The concentration of the test item in the 90% saturated test solution was determined to be 12.64 mg/L (based on analysis of dissolved organic carbon in the test solution). The saturated solution was obtained from an aqueous solution prepared with 1 g/L of test item slow-stirred for 72 h.

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

 

The surface tension of an aqueous solution of the test item was determined as 61.13 ± 0.41 mN/m at 19.9 °C. One measurement series was performed for verification (after 62 minutes). No significant changes and thus no significant dependence on time were observed.

As all measured values were higher than 60 mN/m, the test item is classified as not surface active.

Description of key information

Surface tension = 61.13 mN/m, at 90% saturation expected (12.64 mg/L)
Since the measured result is above the threshold value of 60 mN/m, according to EU A5 criteria, the substance is NOT considered as surface-active under the experimental conditions

Key value for chemical safety assessment

Surface tension:

61.13

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

12.64

Additional information

A fully reliable experimental study, conducted according to a recognized OECD/EU/ISO method and under GLP, is available. It is considered as a key study, and the result is retained as key value.

The concentration of the test item in the 90 % saturated test solution was determined to be 12.64 mg/L (based on analysis of dissolved organic carbon in the test solution).