Chromium tin calcium silicon sphene

Water solubility

Link to relevant study record(s)

Reference

Endpoint:

transformation / dissolution of metals and inorganic metal compounds

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2011-08-23 to 2012-02-14

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

deviations do not effect the validity of the study

Qualifier:

according to guideline

Guideline:

OECD Series on Testing and Assessment No. 29 (23-Jul-2001): Guidance document on transformation/dissolution of metals and metal compounds in aqueous media

Version / remarks:

(ENV/JM/MONO(2001)9): Guidance Document on Transformation / Dissolution of Metals and Metal Compounds in Aqueous Media

Deviations:

yes

Remarks:

please refer to the field " Principles of method if other than guideline"

Qualifier:

according to guideline

Guideline:

other: EEC guideline SANCO/3029/99 rev. 4 dated 11/07/00: Working document “Guidance for generating and reporting methods of analysis in support of residue data requirements for Annex II (part A, Section 4) and Annex III (part A, Section 5)

Deviations:

yes

Remarks:

please refer to the field " Principles of method if other than guideline"

Principles of method if other than guideline:

- As per sponsor request, the 7d-full test was performed with two aqueous solutions at pH 6 and pH 8.
- According to the guideline OECD No. 29, temperature of the reaction vessel should be controlled to +/- 2 °C in the range 20 - 25 °C.
Using a data-logger into the mechanical shaker, the measured temperatures were outside the required range as temperatures ranged:
from 22.4 °C to 32.7 °C with a mean value 28.9 °C in the screening test,
from 23.6 °C to 26.6 °C with a mean value of 24.9 °C in the 7-d test, and
from 18.5 °C to 24.8 °C with a mean of 21.1 °C in the 28-d test.
- The between-vessel variation for the solution with pH 6 after 4 days and 7 days in the 7d-full test and for the solution after 7 days and 14 days in the 28d-full test were not less than the 20 % recommended by OECD Series No. 29.
- The 28-day test with a loading of 1 mg/L was conducted at pH 8 instead of 8.5
- `mass balance (%) after completion of the transformation test´ is missing

GLP compliance:

yes

Type of method:

flask method

Type of test:

screening transformation/dissolution test - sparingly soluble metal compounds

Mean dissolved conc.:

11.5 µg/L

Element analysed:

Sn

Loading of aqueous phase:

100 mg/L

Incubation duration:

24 h

Test conditions:

pH8

Type of test:

screening transformation/dissolution test - sparingly soluble metal compounds

Mean dissolved conc.:

< 0.5 µg/L

Element analysed:

Cr

Loading of aqueous phase:

100 mg/L

Incubation duration:

24 h

Test conditions:

pH8

Type of test:

screening transformation/dissolution test - sparingly soluble metal compounds

Mean dissolved conc.:

5.4 µg/L

Element analysed:

Sn

Loading of aqueous phase:

100 mg/L

Incubation duration:

24 h

Test conditions:

pH 6

Type of test:

screening transformation/dissolution test - sparingly soluble metal compounds

Mean dissolved conc.:

< 0.5 µg/L

Element analysed:

Cr

Loading of aqueous phase:

100 mg/L

Incubation duration:

24 h

Test conditions:

pH6

Type of test:

full transformation/dissolution test - metals and sparingly soluble metal compounds

Mean dissolved conc.:

1.6 µg/L

Element analysed:

Sn

Loading of aqueous phase:

100 mg/L

Incubation duration:

7 d

Test conditions:

pH 6, 22.1 °C

Remarks on result:

other: S.D.: 0.5 µg Sn/L

Type of test:

full transformation/dissolution test - metals and sparingly soluble metal compounds

Mean dissolved conc.:

> 0.5 - < 1 µg/L

Element analysed:

Cr

Loading of aqueous phase:

100 mg/L

Incubation duration:

7 d

Test conditions:

pH 6, 22.1 °C

Remarks on result:

other: LOD (>0.5 µg/L)

Type of test:

full transformation/dissolution test - metals and sparingly soluble metal compounds

Mean dissolved conc.:

19.6 µg/L

Element analysed:

Sn

Loading of aqueous phase:

100 mg/L

Incubation duration:

7 d

Test conditions:

pH 8, 22.2 °C

Remarks on result:

other: S.D.: 0.7 µg Sn/L

Type of test:

full transformation/dissolution test - metals and sparingly soluble metal compounds

Mean dissolved conc.:

< 0.5 µg/L

Element analysed:

Cr

Loading of aqueous phase:

100 mg/L

Incubation duration:

7 d

Test conditions:

pH 8, 22.2 °C

Remarks on result:

other:

Type of test:

full transformation/dissolution test - metals and sparingly soluble metal compounds

Mean dissolved conc.:

< 0.5 µg/L

Element analysed:

Cr, Sn

Loading of aqueous phase:

1 mg/L

Incubation duration:

24 h

Test conditions:

pH: 8, Temp.: 20.0 °C

Remarks on result:

other: < LOD (0.05 µg/L)

Key result

Type of test:

full transformation/dissolution test - metals and sparingly soluble metal compounds

Mean dissolved conc.:

2.2 µg/L

Element analysed:

Sn

Loading of aqueous phase:

1 mg/L

Incubation duration:

7 d

Test conditions:

pH 8, 20.4 °C

Remarks on result:

other: S.D.: 0.5 µg Sn/L

Key result

Type of test:

full transformation/dissolution test - metals and sparingly soluble metal compounds

Mean dissolved conc.:

< 0.5 µg/L

Element analysed:

Cr

Loading of aqueous phase:

1 mg/L

Incubation duration:

7 d

Test conditions:

pH 8, 20.4 °C

Remarks on result:

other:

Key result

Type of test:

full transformation/dissolution test - metals and sparingly soluble metal compounds

Mean dissolved conc.:

3.8 µg/L

Element analysed:

Sn

Loading of aqueous phase:

1 mg/L

Incubation duration:

28 d

Test conditions:

pH 8, 20.0 °C

Remarks on result:

other: S.D.: 0.7 µg Sn/L

Key result

Type of test:

full transformation/dissolution test - metals and sparingly soluble metal compounds

Mean dissolved conc.:

< 0.5 µg/L

Element analysed:

Cr

Loading of aqueous phase:

1 mg/L

Incubation duration:

28 d

Test conditions:

pH 8, 20.0 °C

Remarks on result:

other: < LOD (0.5 µg/L)

Details on results:

For the 7 d and 28 d full tests, the increased between-vessel variation may be due to a particle size distribution of the test item (D10 = 1.7 µm, D50 = 3.8 µm and D90 = 7.4 µm, as per test item Certificate of Analysis) and the corresponding total surface area range that are not as narrow as requested in the OECD Series No. 29 and may result in higher variation.

The precision and the accuracy of the analytical method are in accordance with SANCO/3029/99 rev. 4.
The analytical method was suitable for the determination of chromium and tin in aqueous samples applying ICP-MS.
The analysed range, from 0.1 to 200 µg/L, was found to be linear for chromium and tin, respectively (correlation coefficient > 0.99).
The instrumental limit of detection (IDL) defined as the lowest calibration level, was 0.1 µg/L for chromium and tin, respectively.
The limit of quantification (LOQ) of the method was 1 µg/L for chromium and tin, respectively, defined as the lowest fortification level.
The limit of detection (LOD) of the method, defined as 50 % of the lowest fortification level, was 0.5 µg/L for chromium and tin, respectively.
Concentrations lower than the LOD were classified as not detected (n.d.).
Concentrations higher than the LOD but lower than the LOQ were designated as <1 µg/L for chromium and tin, respectively.
From the results of the accuracy test it can be concluded that there was not a matrix effect and contamination (e.g. by the filter procedure) did not occur during sample processing.

Summary results for the 24h-screening test

Screening Test at 100 mg/L		Cr (µg/L)	Sn (µg/L)
Solution pH 6 T24h	Mean	n.d.	5.4
	SD	-	0.2
	RSD (%)	-	3.8
Solution pH 8 T24h	Mean	n.d.	11.5
	SD	-	0.8
	RSD (%)	-	6.6

Abbreviations:

SD: Standard Deviation; RSD (%): Relative Standard Deviation %

n.d.: lower than the method Limit of Detection (LOD) (0.5 µg/L for Cr).

 

Summary results for the 7d-full test with a loading of 100 mg/L

Full test 7 days at 100 mg/L		Cr (µg/L)	Sn (µg/L)
Solution pH 6 T1d	Mean	n.d.	3.3
	SD	-	0.7
	RSD (%)	-	22.5(*)
Solution pH 6 T4d	Mean	n.d.	2.1
	SD	-	0.3
	RSD (%)	-	16.3
Solution pH 6 T7d	Mean	<1	1.6
	SD	-	0.5
	RSD (%)	-	30.5(*)
Solution pH 8 T1d	Mean	n.d.	4.9
	SD	-	0.6
	RSD (%)	-	11.7
Solution pH 8 T4d	Mean	n.d.	12.4
	SD	-	0.4
	RSD (%)	-	3.3
Solution pH 8 T7d	Mean	n.d.	19.6
	SD	-	0.7
	RSD (%)	-	3.3

n.d.: lower than the method Limit of Detection (LOD) (0.5 µg/L for Cr and Sn, respectively).

<1: lower than the method Limit of Quantification (LOQ) (1 µg/L for Cr) but higher than the method Limit of Detection (LOD) (0.5 µg/L for Cr).

(*)The between-vessel variation for solution with pH 6 after 4 days and 7 days were not less than the 20 % recommended by OECD Series No. 29.

 

Summary results for the 28d-full test with a loading of 1 mg/L

Full test 28 days at 1 mg/L		Cr (µg/L)	Sn (µg/L)
Solution pH 8 T1d	Mean	n.d.	n.d.
	SD	-	-
	RSD (%)	-	-
Solution pH 8 T7d	Mean	n.d.	2.2
	SD	-	0.5
	RSD (%)	-	23.1(*)
Solution pH 8 T14d	Mean	n.d.	3.1
	SD	-	0.7
	RSD (%)	-	21.3(*)
Solution pH 8 T28d	Mean	n.d.	3.8
	SD	-	0.7
	RSD (%)	-	18.7

n.d.: lower than the method Limit of Detection (LOD) (0.5 µg/L for Cr and Sn, respectively).

(*)The between-vessel variation after 7 days and 14 days were not less than the 20% recommended by OECD Series No. 29.

Analytical method (Inductively-Coupled-Plasma Mass-Spectrometry ICP-MS)

 

Specificity

Chromium and tin concentrations of blanks from each test medium were analysed. Chromium and tin concentrations in blanks of the respective media were below the method LOD.

 

Linearity and System Precision

The analysed range of Cr and Sn concentrations, from 0.1 µg/L to 50 µg/L,was found to be linear (correlation coefficient > 0.99 for each metal).

Since the fortification levels for the recovery test were 1 mg/L and 10 mg/L, the linear calibration performed for recovery quantification ranged from 0.1 µg/L to 50 µg/L.

Parameters of linear calibration for Cr analysis:

m (slope): 0.9326

q (intercept): 0.0457

R²(correlation):0.9999

Parameters of linear calibration for Sn analysis:

m (slope): 0.0149

q (intercept): 0.0002

R²(correlation): 0.9999

 

Repeatability (Precision) and Accuracy (Recovery)

For precision, the SANCO/3029/99 rev. 4 guideline requires an RSD to be lower than 20 % for each fortification level.

For accuracy, the SANCO/3029/99 rev. 4 guideline requires mean recovery values for each fortification level in the range from 70 to 110 %, ideally with the mean in the range 80 to 100 %.

Repeatability and Recovery test: Test medium at pH 6

Elution medium pH 6	Cr (µg/L) (1)	Cr Recovery (%)	Sn (µg/L) (1)	Sn Recovery (%)
Solution blank	n.d.	-	n.d.	-
Spike L1	0.96	95.82	0.78	78.07
Spike L2	0.98	97.95	0.77	77.42
Spike L3	0.98	98.40	0.76	76.06
Mean value:	1.0	97.4	0.8	77.2
Standard deviation (SD):	0.01	1.38	0.01	1.03
Relative Standard deviation (RSD (%)):	1.4	1.4	1.3	1.3
Elution medium pH 6	Cr (µg/L) (1)	Cr Recovery (%)	Sn (µg/L) (1)	Sn Recovery (%)
Solution blank	n.d.	-	n.d.	-
Spike H1	9.38	93.78	8.21	82.10
Spike H2	9.30	92.96	8.33	83.26
Spike H3	9.78	97.82	7.92	79.24
Mean value:	9.5	94.9	8.2	81.5
Standard deviation (SD):	0.26	2.60	0.21	2.07
Relative Standard deviation (RSD (%)):	2.7	2.7	2.5	2.5

(1) Mean of two determinations.

n.d.: lower than the method Limit of Detection (LOD) (0.5 µg/L for Cr and Sn, respectively).

Repeatability and Recovery test: Test medium at pH 8

Elution medium pH 8	Cr (µg/L) (1)	Cr Recovery (%)	Sn (µg/L) (1)	Sn Recovery (%)
Solution blank	n.d.	-	n.d.	-
Spike L1	0.99	98.95	0.77	77.20
Spike L2	1.00	99.73	0.79	79.10
Spike L3	1.00	100.30	0.78	78.15
Mean value:	1.0	99.7	0.8	78.1
Standard deviation (SD):	0.01	0.68	0.01	0.95
Relative Standard deviation (RSD (%)):	0.7	0.7	1.2	1.2
Elution medium pH 8	Cr (µg/L) (1)	Cr Recovery (%)	Sn (µg/L) (1)	Sn Recovery (%)
Solution blank	n.d.	-	n.d.	-
Spike H1	9.51	95.06	7.92	79.18
Spike H2	9.46	94.56	7.93	79.27
Spike H3	9.93	99.27	8.33	83.28
Mean value:	9.6	96.3	8.1	80.6
Standard deviation (SD):	0.26	2.58	0.23	2.34
Relative Standard deviation (RSD (%)):	2.7	2.7	2.9	2.9

(1) Mean of two determinations.

n.d.: lower than the method Limit of Detection (LOD) (0.5 µg/L for Cr and Sn, respectively).

Conclusions:

For the 7-d and 28-d full tests, the increased between-vessel variation may be due to a particle size distribution of the test item (D10 = 1.7 µm, D50 = 3.8 µm and D90 = 7.4 µm, as per test item Certificate of Analysis) and the corresponding total surface area range that are not as narrow as requested in the OECD Series No. 29 and may result in higher variation.

The transformation/dissolution of chrome tin pink sphene was measured according to the method OECD test series No. 29 (Guidance document on transformation/dissolution of metals and metal compounds in aqueous media). The transformation/dissolution of the pigment resulted in the following dissolved concentrations:

Full test 7 days at 100 mg/L and pH6: 1.6 ± 0.5 µg Sn/L and >0.5 <1.0 µg Cr/L
Full test 7 days at 100 mg/L and pH8: 19.6 ± 0.7 µg Sn/L and <0.5 µg Cr/L

Full test 7 days at 1 mg/L and pH8: 2.2 ± 0.5 µg Sn/L and <0.5 µg Cr/L
Full test 28 days at 1 mg/L and pH8: 3.8 ± 0.7 µg Sn/L and <0.5 µg Cr/L

Description of key information

The solubility of Chromium tin calcium silicon sphene is < 0.02 wt%. A GLP-conform transformation/dissolution test with a loading of 100 mg/L at pH6 and ph8 over 7 days, revealed higher dissolution at ph 8 than at pH6. Dissolved Cr and Sn concentration at pH8 after 7 days were below LOD (0.5 microg/L) and 19.6 microg/L, respectively. Transformation/dissolution at a loading of 1 mg/L at pH8 over 28 days resulted in dissolved Cr concentrations below < LOD (0.5 mircog/L) after 7 and 28 days. Whereas dissolved Sn concentrations were detected at 2.2 microg/L and 3.8 microg/L after 7 and 28 days, respectively (Pardo Martinez, 2013).

The particle size of the tested sample (BET surface area 1.9 m2/g) is representative for the particle size on the market. Thus, the extent to which "Chromium tin calcium silicon sphene" can produce soluble available ionic and other metal-bearing species in aqueous media is limited.