Naphthenic acids, nickel salts

Water solubility

Link to relevant study record(s)

Reference

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2018-04-03 to 2018-05-08

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Version / remarks:

1995

Deviations:

yes

Remarks:

Two vessels were set up in a parallel design, each vessel was sampled several times instead of sampling one vessel at every point in time/ exclusion of O2 and CO2, under inert gas (argon)

Qualifier:

according to guideline

Guideline:

EU Method A.6 (Water Solubility)

Version / remarks:

2008

Deviations:

yes

Remarks:

Two vessels were set up in a parallel design, each vessel was sampled several times instead of sampling one vessel at every point in time/ exclusion of O2 and CO2, under inert gas (argon)

GLP compliance:

yes (incl. QA statement)

Remarks:

signed 2016-05-31

Type of method:

flask method

Specific details on test material used for the study:

Storage conditions: Room temperature tightly closed

Key result

Water solubility:

486 mg/L

Conc. based on:

test mat. (dissolved fraction)

Loading of aqueous phase:

1 g/L

Incubation duration:

>= 34 - <= 35 d

Temp.:

20 °C

pH:

>= 6.7 - <= 7.5

Remarks on result:

other: S.D.: ± 74.6 mg/L

Remarks:

calculated based on a ni content of 10.55 % and a purity of 90 % (w/w)

Water solubility:

56.9 mg/L

Conc. based on:

element (dissolved fraction)

Remarks:

Ni

Loading of aqueous phase:

1 g/L

Incubation duration:

>= 34 - <= 35 d

Temp.:

20 °C

pH:

>= 6.7 - <= 7.5

Remarks on result:

other: S.D.± 8.75 mg/L

Details on results:

- Temperatire: 20.0 ± 0.2 °C
- pH values:
solutions containing test item: from 6.7 – 6.9 (day 1) to 7.3 – 7.5 (day 34); 7.1 – 7.2 (day 35)
method blanks: from 5.9 – 6.4 (day 1) to 5.6 – 6.2 (day 35)
- The turbidity in samples from test was always <1 NTU indicating that filtered solutions did not contain any undissolved material.

ICP-OES

ICP-OES measurement with corresponding LOD/LOQ, correlation coefficient and sum of quality assurance samples and recovery

date	Chosen wavelength [nm]	LOD (µg/L)	LOQ (µg/L)	correlation coefficient	Sum of quality assurance samples	Recovery / validity of quality assurance samples [%]
April 26, 2018; measurement of test samples (21d and 22d) and method blanks	Ni: 231.604	Ni: 1.11	Ni: 3.33	Ni: 0.99996	Ni: 10	Ni: 100

Recovery/validation data nickel of measurement April 26, 2018

	Recovery [%]	SD [%]	n (total)	n (valid)
TMDA-70.2 (dilution factor 2), nominal value Ni: 333 µg/L – diluted 167 µg/L	105	0.6	3	3
Quality control standard (Roth) 300 µg/L	105	0.3	3	3
Recalibration standard 100 µg/L	101	0.7	3	3

 

Fortification of measurement series April 26, 2018

Sample	element	measured concentration [µg/L]	calculated level after addition [µg/L]	recovery [µg/L] / [%]
Vessel 1 sample a 21d – 1 mL sample 4 mL 400 µg/L standard	Ni	410	402	405 / 101

ICP-MS

ICP-MS measurement with corresponding LOD/LOQ, correlation coefficient and sum of quality assurance samples and recovery

Chosen isotope and gas mode	LOD (µg/L)	LOQ (µg/L)	correlation coefficient	Sum of quality assurance samples	Recovery / validity of quality assurance samples [%]
April 10, 2018; measurement of samples of the main test 1, 2 and 3 d
Ni:^60Ni [Helium mode]	Ni: 0.006	Ni: 0.019	Ni: 0.9999	Ni: 13	Ni: 100
April 19, 2018; measurement of samples of the main test 13 d and 14 d
Ni:^60Ni [noGas mode]	Ni: 0.015	Ni: 0.046	Ni: 1.0000	Ni: 10	Ni: 100
May 07, 2018; measurement of samples of the main test 34 d
Ni:^60Ni [HiHelium mode]	Ni: 0.006	Ni: 0.017	Ni: 0.9995	Ni: 7	Ni: 100
May 08, 2018; measurement of samples of the main test 35 d and remeasurement of 34 d –only test item samples
Ni:^60Ni [Helium mode]	Ni: 0.005	Ni: 0.016	Ni: 1.0000	Ni: 14	Ni: 100

 

Recovery/validation data nickel of measurement

	Recovery [%]	SD [%]	n (total)	n (valid)
April 10, 2018
TMDA-70.2 (dilution factor 2), nominal value Ni: 333 µg/L – diluted 167 µg/L	101	2.4	4	4
Quality control standard (Roth) 250 µg/L	107	1.9	4	4
Recalibration standard 100 µg/L	97.8	1.8	4	4
April 19, 2018
TMDA-70.2 (dilution factor 4), nominal value Ni: 333 µg/L – diluted 83.3 µg/L	99.6	1.43	3	3
Quality control standard (Roth) 250 µg/L	104	4.7	3	3
Recalibration standard 100 µg/L	96.6	0.9	3	3
May 07, 2018
TMDA-70.2 (dilution factor 2), nominal value Ni: 333 µg/L – diluted 167 µg/L	100	0.5	2	2
Quality control standard (Roth) 400 µg/L	101	0.4	2	2
Recalibration standard 100 µg/L	102	2.2	3	3
May 08, 2018
TMDA-70.2 (dilution factor 2), nominal value Ni: 333 µg/L – diluted 167 µg/L	101	2.6	4	4
Quality control standard (Roth) 400 µg/L	98.0	2.5	4	4
Recalibration standard 100 µg/L	96.7	1.6	4	4

 

 

Ni fortification

sample	Element	measured concentration [µg/L]	calculated level after addition [µg/L]	recovery [µg/L] / [%]
April 10, 2018
Vessel 1 sample a 2 d sampling time (dilution factor 100) - 1 mL sample + 4 mL of standard 100 µg/L	Ni	149	110	108 / 98.4
April 19, 2018.
Vessel 1 sample a 14 d sampling time (dilution factor 100) - 1 mL sample + 4 mL of standard 300 µg/L	Ni	290	298	293 / 98.2
May 08, 2018.
Vessel 1 sample a 34 d sampling time (dilution factor 200) - 1 mL sample + 4 mL of standard 300 µg/L	Ni	326	305	307 / 101
Vessel 1 sample a 35 d sampling time (dilution factor 200) - 1 mL sample + 4 mL of standard 300 µg/L	Ni	308	302	299 / 99.1

 

Conclusions:

Under the conditions of this test (under exclusion of CO2 and O2, under inert gas; flask method; loadings of 1.003 g and 1.002 g/L test substance in vessel 1 and 2, respectively), a solubility equilibrium was reached at day 34, 35 of testing. The mean measured amount of dissolved nickel on day 34 and 35 at 20 ± 1°C is 56.9 ± 8.75 mg/L (determined as dissolved nickel, separated by filtration from undissolved test item). This corresponds to a water solubility of dissolved naphthenic acids, nickel salts of 486 ± 74.6 mg/L, calculated based on a nickel content of 10.55 % and a test substance purity of 90% (w/w). Solution pH in samples containing the test item remained at 6.7 – 7.5 while the pH in method blanks ranged from 5.6 – 6.4.

Description of key information

According to OECD Guideline 105 (1995) and EU Method 440/2008 A.6, the test item naphthenic acids, nickel salts has a water solubility of 486 mg/L at 20 °C.

Key value for chemical safety assessment

Water solubility:

486 mg/L

at the temperature of:

20 °C

Additional information

Under the conditions of this test (under exclusion of CO₂and O₂, under inert gas; flask method; loadings of 1.003 g and 1.002 g/L test substance in vessel 1 and 2, respectively), a solubility equilibrium was reached at day 34, 35 of testing. The mean measured amount of dissolved nickel on day 34 and 35 at 20 ± 1 °C is 56.9 ± 8.75 mg/L (determined as dissolved nickel, separated by filtration from undissolved test item). This corresponds to a water solubility of dissolved naphthenic acids, nickel salts of 486 ± 74.6 mg/L, calculated based on a nickel content of 10.55 % and a test substance purity of 90 % (w/w). Solution pH in samples containing the test item remained at 6.7 – 7.5 while the pH in method blanks ranged from 5.6 – 6.4.