Zinc diricinoleate

Water solubility

Administrative data

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2012

Report date:

2012

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

other: OECD Series on Testing and Assessment Number 29, 2001

Deviations:

no

GLP compliance:

yes

Type of method:

other: Transformation/dissolution protocoll

Test material

Test material information

Constituent 1

Reference substance name:

Zinc diricinoleate

EC Number:

235-911-4

EC Name:

Zinc diricinoleate

Cas Number:

13040-19-2

Molecular formula:

C18H34O3.1/2Zn

IUPAC Name:

zinc bis(12-hydroxyoctadec-9-enoate)

Constituent 2

Reference substance name:

Zinc ricinoleate

IUPAC Name:

Zinc ricinoleate

Results and discussion

Water solubility

Water solubility 1

Water solubility:

70.8 other: Transformation/dissolution test, µg/L dissolved zinc

Temp.:

21.4 °C

pH:

6

Remarks on result:

other: at 1 mg/L loading, after 672 hours; 70.8 µg dissolved zinc/L correspond to 727.7 µg dissolved test item/L based on an analytically determined zinc content of 9.73 %.

Water solubility 2

Water solubility:

418 other: Transformation/dissolution test, µg/L dissolved zinc

Temp.:

21.5 °C

pH:

6

Remarks on result:

other: at 10 mg loading after 168 hours; 418 µg dissolved zinc/L correspond to 4296 µg dissolved test item/L based on an analytically determined zinc content of 9.73 %.

Water solubility 3

Water solubility:

1 578 other: Transformation/dissolution test, µg/L dissolved zinc

Temp.:

21.5 °C

pH:

6

Remarks on result:

other: at 100 mg loading after 168 hours; 1578 µg dissolved zinc/L correspond to 16218 µg dissolved test item/L based on an analytically determined zinc content of 9.73 %.

Any other information on results incl. tables

Results test conditions

 

Temperature:

The mean temperatures thermostatically controlled room were 21.4 ± 0.3 °C for screening test, 21.0 ± 0.4 °C for 1 mg/L and 21.5 ± 0.4 °C for 10 mg/L and 100 mg/L test, respectively. Therefore the mean temperatures are in agreement with the OECD guidance document 29.

 

Solution pH

The solution pHs of test vessels remained relatively constant during the 28 days for both pH treatments:

1 mg test item/L pH 7.5 – 8.0

method blanks pH 5.8 – 6.2

 

10 mg test item/L: over the 7 days, solution pHs in vessels loaded with 10 mg/L of the test item increased from 7.3 to 8.1 (target pH 8) and from 5.5 to 5.9 (target pH 6), respectively.

method blanks: pH remained relatively constant (8.0 ± 0.2 and 6.0 ± 0.2).

100 mg test item and method blanks at pH 6 and 8, the pHs ranged from 7.1 – 8.2 and 5.1 – 6.1, respectively.

 

Oxygen levels

Oxygen levels in all test vessels (all loadings) were in the range recommended by the OECD Test Guidance 29 during the test: above 70 % of oxygen saturation at 8.5 mg/L (70 % of 8.5 mg/L = 6 mg/L).

Results Zn measurements

In the following tables and figures (Table1-Table4andFigure1-Figure3) measured dissolved Zn concentrations are compiled for all loadings and pH treatments in the screening and full test.

Table 3:Screening test: Measured dissolved Zn concentrations for the loading of 100 mg/L

(target pH 8: 1, 2, 3; target pH 6: 4, 5, 6 – triplicate vessels per pH, duplicate samples per vessel).

sample	target pH	mean V conc. per vessel ± range [µg/L]	mean V conc. all vessels ± SD [µg/L] #
1 24h	8	1152 ± 5	1164 ± 35
2 24h	8	1207 ± 4
3 24h	8	1133 ± 9
4 24h	6	1213 ± 25	1267± 199
5 24h	6	1078 ± 15
6 24h	6	1511 ± 31

#      Internal calculations were performed with more digits, values were rounded

Table 4:Full test: Measured dissolved Zn concentrations for theloading of 1 mg/L

(1, 2, 3 – triplicate vessels, duplicate samples per vessel), within- and between-vessel variations and variations of mean Zn concentrations between sampling intervals

sample	target pH	mean V conc. per vessel ± range [µg/L]	within vessel variation [%] #	mean V conc. all vessels ± SD [µg/L] #	between vessel variation [%] #	variations of mean Zn conc. between sampling intervals [%] #
1 2h	6	<LOQ (10.1)$	-	-	-	-
2 2h	6	<LOQ (9.9)$	-
3 2h	6	<LOQ (9.8)$	-
1 6h	6	16.2 ± 0.1	0.8	15.8 ± 0.8	5.4	-
2 6h	6	16.4 ± 0.1	0.3
3 6h	6	14.7 ± 0.4	2.7
1 24h	6	32.2 ± 0.7	2.2	33.9 ± 1.8	5.3	115
2 24h	6	36.1 ± 0.2	0.6
3 24h	6	33.4 ± 0.1	0.2
1- 96h	6	61.9 ± 0.1	0.1	60.4 ± 7.3	12.2	78.1
2- 96h	6	51.5± 0.7	1.5
3 -96h	6	67.8± 0.1	0.1
1 -168h	6	73.6 ± 0.4	0.5	71.3 ± 12.0	16.8	18.0
2 -168h	6	56.8 ±0.2	0.4
3 -168h	6	83.4 ±0.5	0.6
1 -336h	6	75.8 ± 0.4	0.6	74.1 ± 10.7	14.4	4.0
2 -336h	6	61.4 ± 0.5	0.9
3 -336h	6	85.1 ± <0.1	<0.1
1 -504h	6	72.6 ± 0.4	0.6	72.6 ± 8.0	11.1	- 2.0
2 -504h	6	63.6± 0.2	0.3
3 -504h	6	81.6± <0.1	0.1
1 -672h	6	70.9 ± 0.1	0.1	70.8 ± 7.2	10.2	- 2.5
2 -672h	6	62.7± 0.2	0.3
3 -672h	6	78.8± 0.2	0.2

#      Internal calculations were performed with more digits, values were rounded

$      LOQ (Limitofquantification) = 14 µg/L

Table 5:  Full test: Measured dissolved Zn concentrations for theloading of 10 mg/L

(1, 2, 3 – triplicate vessels, duplicate samples per vessel), within- and between-vessel variations and variations of mean Zn concentrations between sampling intervals

sample	target pH	mean V conc. per vessel ± range [µg/L]	within vessel variation [%] #	mean V conc. all vessels ± SD [µg/L] #	between vessel variation [%] #	variations of mean Zn conc.between sampling intervals [%] #
1 -2h	6	31.3 ± 0.3	0.9	32.2 ± 2.4	7.4	-
2 -2h	6	33.8 ± 0.4	1.3
3 -2h	6	31.5 ± 4.4	14.1
1 -6h	6	65.2 ± 0.7	1.1	67.0 ± 6.8	10.2	108
2 -6h	6	75.4± 0.2	0.3
3 -6h	6	60.5 ± 0.1	0.1
1 -24h	6	178 ± 1	0.3	184 ± 12	6.3	174
2 -24h	6	198 ± <1	0.2
3 -24h	6	174± 1	0.5
1 -96h	6	343± 3	0.8	329 ± 48	14.6	79.1
2 -96h	6	374± 2	0.5
3 -96h	6	270± 1	0.5
1 -168h	6	471 ± 2	0.5	418 ± 75	18.0	27.1
2 -168h	6	462± 5	1.0
3 -168h	6	321± 1	0.4

Table 6:    Full test: Measured dissolved Zn concentrations for theloading of 100 mg/L

(1, 2, 3 – triplicate vessels, duplicate samples per vessel), within- and between-vessel variations and variations of mean Zn concentrations between sampling intervals

sample	target pH	mean V conc. per vessel ± range [µg/L]	within vessel variation [%] #	mean V conc. all vessels ± SD [µg/L] #	between vessel variation [%] #	variations of mean Zn conc.between sampling intervals [%] #
1 -2h	6	150 ± 1.4	0.9	120 ± 24.2	20.3	-
2 -2h	6	97.4 ± 2.9	3.0
3 -2h	6	112 ± < 0.1	< 0.1
1 -6h	6	349 ± 7.6	2.2	275± 59.5	21.6	130
2 -6h	6	222± 1.5	0.7
3 -6h	6	254 ± 0.5	0.2
1 -24h	6	980 ± 10.7	1.1	776± 161	20.7	182
2 -24h	6	643 ± 4.8	0.7
3 -24h	6	705± 1.7	0.2
1 -96h	6	1300± 9.2	0.7	1379± 257	18.6	77.7
2 -96h	6	1698± 14.8	0.9
3 -96h	6	1140± 12.7	1.1
1 -168h	6	1343 ± 1.4	0.1	1578± 400	25.3	14.4
2 -168h	6	2093± 39.6	1.9
3 -168h	6	1299± 23.3	1.8

#      Internal calculations were performed with more digits, values were rounded

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information): insoluble (< 0.1 mg/L)
At a loading of 1 mg/L the equilibrium for dissolution of zinc from zinc ricinoletae at pH 6 had been reached after 627 h (28 d). Zinc concentrations were 70.8 ± 7.2 µg/L at equilibrium after 28 days.
At a loading of 10 mg test item/L dissolved zinc concentrations after 7 days were at 418 ± 75 µg/L at pH 6.
At a loading of 100 mg/L dissolved zinc concentrations after 7 days were at 1578 ± 400 µg/L at pH 6.

Executive summary:

The test objective was to study the transformation & dissolution of zinc ricinoleate under environmentally relevant conditions over up to 28 days.The test was performed according to OECD guidance document 29 (2001)over 7 days with loadings of 1 mg/L, 10 mg/L and 100 mg/L. The test with a loading of 1 mg/L was prolonged to 28 days.

The OECD guidance document 29 requests the performance of the test at a pH which maximizes the dissolution. Therefore, prior to the full test a screening over 24 h (agitation at 100 rpm, 21.5 ± 1.5 °C, loadings of 100 mg/L) was conducted in test media at pH 6 and pH 8 in triplicate vessels and duplicate samples per vessel.

After 24 h the dissolved Zn concentrations were 1.267 ± 0.199 mg/L and 1.164 ± 0.035 mg/L for pH 6 and 8, respectively. Based on these results the full test was performed in test media at a target pH of 6.

Solutions in the full test weresampled after 2 h, 6 h, 24 h, 96 h (4 d), 168 h (7 d). For the test up to 28 days samples were additionally taken after 336 h (14 d), 504 h (21 d) and 672 h (28 d). Solution pHs, oxygen concentrations and total dissolved zinc concentrations were measured.The test was performed in triplicates (three replicates per pH treatment, sampled twice at each sampling point).

Final results:

Measured pHs and oxygen levelsas well as mean temperatures of all loadings werein compliance with the requirements of the OECD-Guidance document 29.

A first order kinetic modelcan be clearly correlated to the dissolution curves for the full testwith the following mathematical equation:

C(t) = A (1 -e^(-kt))

C(t): total dissolved metal concentration [µg/L] at time t

A:     limiting dissolved metal concentration [µg/L] at apparent equilibrium (test end points)

k:     first order rate constant [1/h]

t:      time [h]

 

Loading of 1 mg/L

Under the described conditions of this full test with zinc ricinoleate at pH 6, dissolved zinc concentrations were at a loading of 1 mg/L after 28 days 70.8 ± 7.2 µg/L. According to the guidance document “[…] the test can be stopped when three subsequent total dissolved metal concentration data points vary no more than 15%” [I]. Therefore, the equilibrium has been reached after 627 h (28 d) for the loading of 1 mg/L.

For the mean dissolution of zinc for the loading of 1 mg/L the following values for the modeled first order equation could be assigned:

A=70.76 µg/L;k=0.0328 / h

The OECD Series 29 requires a limit of 20 % and 10 % for the between-vessel and the within-vessel variation, respectively.The observed variations within and between the test flasksare in compliance for the loading of 1 mg/L.

 

At aloading of 10 mg/Ldissolved zinc concentrations after 7 days were at 418 ± 75 µg/L at pH 6.The observed variations within and between the test flasksare in compliance with the guidance document for the loading of 10 mg/L, except for within variation of vessel 3 after 2 h (14.1 %).

For the mean dissolution of zinc for the loading of 10 mg/Lthe following values for the modeled first order equation could be assigned:

A=418.0 µg/L;k=0.0197 / h

  

At aloading of 100 mg/Ldissolved zinc concentrations after 7 days were at 1578 ± 400 µg/L at pH 6.The observed variations between the test flasksare mostly > 20 %.One reason for the observed increased between-vessel variations might be the wider particle size distribution of the test item. Therefore, the particle size distribution of each loading replicate may differ resulting in differing overall surface areas. Furthermore, as the surface area is affecting transformation and dissolution of sparingly soluble metals, increased between-vessel variations may be observed in tests of materials with wider particle size distributions. It is only “[…] reasonable to anticipate that for a constant loading of a substance, tested in a narrow particle size (e.g., 37 - 44 µm) and total surface area range, the within-vessel variation in transformation data should be less than 10 % and the between-vessel variation should be less than 20 %" [I].

For the mean dissolution of zinc for the loading of 100 mg/Lthe following values for the modeled first order equation could be assigned:

A=1578 µg/L;k=0.0328 / h