Spinels, chromium iron manganese brown

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:

2012-06-21 to 2012-07-30

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

`mass balance (%) after completion of the transformation test´ is missing; The 28d-test was performed at pH 6 and 8, according to OECD 29 a range from pH 5.5 to 8.5 should be covered.

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 "Rationale for reliability incl. deficiencies" above

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:

no

GLP compliance:

yes

Type of method:

flask method

Type of test:

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

Mean dissolved conc.:

< 0.5 µg/L

Element analysed:

Fe, Cr

Loading of aqueous phase:

1 mg/L

Incubation duration:

24 h

Test conditions:

pH 6, 22.1 °C

Remarks on result:

other:

Type of test:

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

Mean dissolved conc.:

> 0.5 - < 1 µg/L

Element analysed:

Mn

Loading of aqueous phase:

1 mg/L

Incubation duration:

24 h

Test conditions:

pH 6, 22.1 °C

Remarks on result:

other: >LOD,

Key result

Type of test:

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

Mean dissolved conc.:

< 0.5 µg/L

Element analysed:

Fe, Cr

Loading of aqueous phase:

1 mg/L

Incubation duration:

7 d

Test conditions:

pH 6, 22.1 °C

Remarks on result:

other:

Key result

Type of test:

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

Mean dissolved conc.:

> 0.5 - < 1 µg/L

Element analysed:

Mn

Loading of aqueous phase:

1 mg/L

Incubation duration:

7 d

Test conditions:

pH 6, 22.1 °C

Remarks on result:

other: >LOD,

Key result

Type of test:

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

Mean dissolved conc.:

< 0.5 µg/L

Element analysed:

Fe, Cr

Loading of aqueous phase:

1 mg/L

Incubation duration:

28 d

Test conditions:

pH 6, 22.1 °C

Remarks on result:

other:

Key result

Type of test:

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

Mean dissolved conc.:

> 0.5 - < 1 µg/L

Element analysed:

Mn

Loading of aqueous phase:

1 mg/L

Incubation duration:

28 d

Test conditions:

pH 6, 22.1 °C

Remarks on result:

other: >LOD,

Type of test:

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

Mean dissolved conc.:

< 0.5 µg/L

Element analysed:

Fe, Cr, Mn

Loading of aqueous phase:

1 mg/L

Incubation duration:

24 h

Test conditions:

pH 8, 22.1 °C

Remarks on result:

other:

Key result

Type of test:

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

Mean dissolved conc.:

< 0.5 µg/L

Element analysed:

Fe, Cr, Mn

Loading of aqueous phase:

1 mg/L

Incubation duration:

7 d

Test conditions:

pH 8, 22.0 °C

Remarks on result:

other:

Key result

Type of test:

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

Mean dissolved conc.:

< 0.5 µg/L

Element analysed:

Fe, Cr, Mn

Loading of aqueous phase:

1 mg/L

Incubation duration:

28 d

Test conditions:

pH 8, 22.2 °C

Remarks on result:

other:

Details on results:

The analytical method was shown to be suitable for low content determination of iron, chromium and manganese in aqueous samples applying ICP-MS.
The analyzed range, from 0.1 to 200 µg/L, was found to be linear for iron, chromium and manganese (correlation coefficient > 0.99).
The instrumental limit of detection (IDL) defined as the lowest calibration level, was 0.1 µg/L for iron, chromium and manganese, respectively.
The limit of quantification (LOQ) of the method was 1 µg/L for iron, chromium and manganese, 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 iron, chromium and manganese, respectively.
Metal concentrations lower than the LOD were classified as not detected (n.d.).
Metal concentrations higher than the LOD but lower than the LOQ were designated as <1 µg/L for iron, chromium and manganese, respectively.
The precision and the accuracy of the analytical method are in accordance with SANCO/3029/99 rev. 4.
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 28d-full test with a loading of 1 mg/L at pH 6

Full test 28 days at 1 mg/L		Fe (µg/L)	Cr (µg/L)	Mn (µg/L)
Solution pH 6 T0h	Mean	n.d.	n.d.	n.d.
	SD	-	-	-
	RSD (%)	-	-	-
Solution pH 6 T2h	Mean	n.d.	n.d.	n.d.
	SD	-	-	-
	RSD (%)	-	-	-
Solution pH 6 T6h	Mean	n.d.	n.d.	n.d.
	SD	-	-	-
	RSD (%)	-	-	-
Solution pH 6 T1d	Mean	n.d.	n.d.	<1
	SD	-	-	-
	RSD (%)	-	-	-
Solution pH 6 T4d	Mean	n.d.	n.d.	<1
	SD	-	-	-
	RSD (%)	-	-	-
Solution pH 6 T7d	Mean	n.d.	n.d.	<1
	SD	-	-	-
	RSD (%)	-	-	-
Solution pH 6 T14d	Mean	n.d.	n.d.	<1
	SD	-	-	-
	RSD (%)	-	-	-
Solution pH 6 T21d	Mean	n.d.	n.d.	<1
	SD	-	-	-
	RSD (%)	-	-	-
Solution pH 6 T28d	Mean	n.d.	n.d.	<1
	SD	-	-	-
	RSD (%)	-	-	-

Abbreviations: S.D.: Standard Deviation; RSD %: Relative Standard Deviation %

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

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

Summary results for the 28d-full test with a loading of 1 mg/L at pH 8

Full test 28 days at 1 mg/L		Fe (µg/L)	Cr (µg/L)	Mn (µg/L)
Solution pH 8 T0h	Mean	n.d.	n.d.	n.d.
	SD	-	-	-
	RSD (%)	-	-	-
Solution pH 8 T2h	Mean	n.d.	n.d.	n.d.
	SD	-	-	-
	RSD (%)	-	-	-
Solution pH 8 T6h	Mean	n.d.	n.d.	n.d.
	SD	-	-	-
	RSD (%)	-	-	-
Solution pH 8 T1d	Mean	n.d.	n.d.	n.d.
	SD	-	-	-
	RSD (%)	-	-	-
Solution pH 8 T4d	Mean	n.d.	n.d.	n.d.
	SD	-	-	-
	RSD (%)	-	-	-
Solution pH 8 T7d	Mean	n.d.	n.d.	n.d.
	SD	-	-	-
	RSD (%)	-	-	-
Solution pH 8 T14d	Mean	n.d.	n.d.	n.d.
	SD	-	-	-
	RSD (%)	-	-	-
Solution pH 8 T21d	Mean	n.d.	n.d.	n.d.
	SD	-	-	-
	RSD (%)	-	-	-
Solution pH 8 T28d	Mean	n.d.	n.d.	n.d.
	SD	-	-	-
	RSD (%)	-	-	-

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

Parameters of linear calibration for Fe analysis of solutions from the 28d-full test:

m (slope): 0.6978

q (intercept): 0.3878

R²(correlation): 1.0000

Parameters of linear calibration for Cr analysis of solutions from the 28d-full test:

m (slope): 0.8162

q (intercept): 0.0236

R²(correlation): 0.9999

Parameters of linear calibration for Mn analysis of solutions from the 28d-full test:

m (slope): 0.4749

q (intercept): 0.0064

R²(correlation): 0.9999

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

 

Specificity

Iron, chromium and manganese concentrations of blanks from each test medium were analyzed. Iron, chromium and manganese concentrations in blanks of the respective media were below the method LOQ.

 

Linearity and System Precision

The analysed range of iron, chromium and manganese concentrations, from 0.1 µg/L to 200 µg/L,was found to be linear (correlation coefficient > 0.99 for metal).

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

Parameters of linear calibration for Fe analysis of solutions from the recovery test:

m (slope): 0.6489

q (intercept): 0.2402

R²(correlation): 0.9992

Parameters of linear calibration for Cr analysis of solutions from the recovery test:

m (slope): 0.7453

q (intercept): 0.0099

R²(correlation): 0.9999

Parameters of linear calibration for Mn analysis of solutions from the recovery test:

m (slope): 0.4329

q (intercept): 0.0084

R²(correlation): 1.0000

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 %.

Recovery (Fe)

Test  Medium	Spike add	Mean Found	RSD (%)	Recovery Mean
pH 6	1 µg/L	0.8 µg/L	4.3	81.9 %
	10 µg/L	9.8 µg/L	2.4	98.1 %
pH 8	1 µg/L	0.7 µg/L	9.9	71.8 %
	10 µg/L	8.0 µg/L	1.9	79.6 %

Recovery (Cr)

Test Medium	Spike add	Mean Found	RSD (%)	Recovery Mean
pH 6	1 µg/L	1.0 µg/L	3.5	101.1 %
	10 µg/L	10.6 µg/L	2.4	105.8 %
pH 8	1 µg/L	1.0 µg/L	4.7	97.5 %
	10 µg/L	10.0 µg/L	1.1	99.9 %

Recovery (Mn)

Test Medium	Spike add	Mean Found	RSD (%)	Recovery Mean
pH 6	1 µg/L	1.0 µg/L	4.5	102.8 %
	10 µg/L	10.7 µg/L	2.3	107.2 %
pH 8	1 µg/L	1.1 µg/L	2.1	108.6 %
	10 µg/L	10.7 µg/L	0.3	106.9 %

Repeatability and Recovery test: Test medium at pH 6

Elution medium pH 6	Fe (µg/L) (1)	Fe Rec (%)	Cr (µg/L) (1)	Cr Rec (%)	Mn (µg/L) (1)	Mn Rec (%)
Solution blank	n.d.	-	n.d.	-	n.d.	-
Spike L1	0.80	80.24	1.00	100.00	1.01	100.52
Spike L2	0.86	86.01	1.05	105.04	1.08	108.12
Spike L3	0.80	79.58	0.98	98.17	1.00	99.73
Mean value:	0.8	81.9	1.0	101.1	1.0	102.8
Standard deviation (SD):	0.04	3.53	0.04	3.56	0.05	4.63
Relative Standard deviation (RSD (%)):	4.3	4.3	3.5	3.5	4.5	4.5
Elution medium pH 6	Fe (µg/L) (1)	Fe Rec (%)	Cr (µg/L) (1)	Cr Rec (%)	Mn (µg/L) (1)	Mn Rec (%)
Solution blank	n.d.	-	n.d.	-	n.d.	-
Spike H1	10.08	100.78	10.88	108.81	10.99	109.92
Spike H2	9.74	97.36	10.44	104.41	10.52	105.23
Spike H3	9.62	96.23	10.43	104.30	10.65	106.50
Mean value:	9.8	98.1	10.6	105.8	10.7	107.2
Standard deviation (SD):	0.24	2.37	0.26	2.58	0.24	2.43
Relative Standard deviation (RSD (%)):	2.4	2.4	2.4	2.4	2.3	2.3

(1) Mean of two determinations.

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

Repeatability and Recovery test: Test medium at pH 8

Elution medium pH 8	Fe (µg/L) (1)	Fe Rec (%)	Cr (µg/L) (1)	Cr Rec (%)	Mn (µg/L) (1)	Mn Rec (%)
Solution blank	n.d.	-	n.d.	-	n.d.	-
Spike L1	0.79	78.92	1.01	100.69	1.10	109.53
Spike L2	0.65	64.64	0.92	92.28	1.06	105.95
Spike L3	0.72	71.86	0.99	99.46	1.10	110.19
Mean value:	0.7	71.8	1.0	97.5	1.1	108.6
Standard deviation (SD):	0.07	7.14	0.05	4.54	0.02	2.28
Relative Standard deviation (RSD (%)):	9.9	9.9	4.7	4.7	2.1	2.1
Elution medium pH 8	Fe (µg/L) (1)	Fe Rec (%)	Cr (µg/L) (1)	Cr Rec (%)	Mn (µg/L) (1)	Mn Rec (%)
Solution blank	n.d.	-	n.d.	-	n.d.	-
Spike H1	8.11	81.12	10.08	100.78	10.69	106.95
Spike H2	7.96	79.62	10.03	100.27	10.72	107.23
Spike H3	7.81	78.13	9.87	98.69	10.67	106.66
Mean value:	8.0	79.6	10.0	99.9	10.7	106.9
Standard deviation (SD):	0.15	1.50	0.11	1.09	0.03	0.29
Relative Standard deviation (RSD (%)):	1.9	1.9	1.1	1.1	0.3	0.3

(1) Mean of two determinations.

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

Certified Reference Material analysis

	Ratio Fe/Ge	Fe (µg/L)	Ratio Cr/Ge	Cr (µg/L)	Ratio Mn/Ge	Mn (µg/L)
Certified Reference Material A	18.5018	28.10	13.4226	18.00	8.5153	19.65
Certified Reference Material B	17.6145	26.74	12.7172	17.05	8.1777	18.87
Certified Reference Material C	17.3345	26.31	12.5352	16.81	8.1190	18.74
Mean value (µg/L):	27.05		17.28		19.09
Standard deviation (SD):	0.94		0.63		0.49
Relative Standard deviation (RSD%):	3.5		3.6		2.6

Conclusions:

The analytical method was shown to be suitable for low content determination of iron, chromium and manganese in aqueous samples applying ICP-MS.
The analyzed range, from 0.1 to 200 µg/L, was found to be linear for iron, chromium and manganese (correlation coefficient > 0.99).
The instrumental limit of detection (IDL) defined as the lowest calibration level, was 0.1 µg/L for iron, chromium and manganese, respectively.
The limit of quantification (LOQ) of the method was 1 µg/L for iron, chromium and manganese, 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 iron, chromium and manganese, respectively.
Metal concentrations lower than the LOD were classified as not detected (n.d.).
Metal concentrations higher than the LOD but lower than the LOQ were designated as <1 µg/L for iron, chromium and manganese, respectively.
The precision and the accuracy of the analytical method are in accordance with SANCO/3029/99 rev. 4.
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.

The water solubility of spinels, chromium iron manganese brown 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 oft he pigment resulted in the following dissolved concentrations:

Full test 7 days at 1 mg/L and pH 6: <1 µg Mn/L but >0.5 µg Mn/L; <0.5 µg Fe and Cr/L
Full test 7days at 1 mg/L and pH 8: <0.5 µg Mn, Fe and Cr/L

Full test 28 days at 1 mg/L and pH 6: <1 µg Mn/L but >0.5 µg Mn/L; <0.5 µg Fe and Cr/L
Full test 28 days at 1 mg/L and pH 8: <0.5 µg Mn, Fe and Cr/L


The dissolved Cr, Mn, Fe concentrations were below the LoD (0.5µg/L) after 28 days at a loading of 1 mg/L, referring to a total solubility of < 0.05wt %.
Thus, the extent to which the pigment can produce soluble available ionic and other metal-bearing species in aqueous media is limited.

Description of key information

The solubility of spinels, chromium iron manganese brown is < 0.05 wt% at a 1mg/L loading at pH 6 and 8. A GLP-conform transformation/dissolution test with a loading of 1 mg/L at pH 6 and pH 8 over 28 days, resulted in dissolved Cr, Mn, Fe concentrations below LOD/LoQ (Pardo Martinez, 2013).

The particle size of the tested sample (BET surface area 1.1 m2/g) is representative for the particle size on the market. Thus, the extent to which " spinels, chromium iron manganese brown " can produce soluble available ionic and other metal-bearing species in aqueous media is limited.