Cobalt chromite blue green spinel

Water solubility

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

transformation / dissolution of metals and inorganic metal compounds

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2012-03-23 to 2012-09-18

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

(a) the 28-day test with a loading of 1 mg/L was conducted at pH 6 and 8 instead of 5.5 and 8.5. (b) `mass balance (%) after completion of the transformation test´ is missing (c) The within-vessel variation was not always less than 10 % (d) The LOD should be lower

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:

yes

Remarks:

please refer to the field "Rationale for reliability incl. deficiencies" above

GLP compliance:

yes

Type of method:

flask method

Type of test:

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

Mean dissolved conc.:

1.4 µg/L

Element analysed:

Al

Loading of aqueous phase:

1 mg/L

Incubation duration:

24 h

Test conditions:

pH 6, 21.1 °C

Remarks on result:

other: S.D.: 0.2 µg Al/L

Type of test:

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

Mean dissolved conc.:

< 0.5 µg/L

Element analysed:

Co, Cr

Loading of aqueous phase:

1 mg/L

Incubation duration:

24 h

Test conditions:

pH 6, 21.1 °C

Remarks on result:

other: < LOD

Key result

Type of test:

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

Mean dissolved conc.:

3 µg/L

Element analysed:

Al

Loading of aqueous phase:

1 mg/L

Incubation duration:

7 d

Test conditions:

pH 6, 20.0 °C

Remarks on result:

other: S.D.: 0.3 µg Al/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:

Co, Cr

Loading of aqueous phase:

1 mg/L

Incubation duration:

7 d

Test conditions:

pH 6, 20 °C

Remarks on result:

other: < LOD

Key result

Type of test:

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

Mean dissolved conc.:

1.9 µg/L

Element analysed:

Al

Loading of aqueous phase:

1 mg/L

Incubation duration:

28 d

Test conditions:

pH 6, 21.4 °C

Remarks on result:

other: S.D.: 0.1 µg Al/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:

Co, Cr

Loading of aqueous phase:

1 mg/L

Incubation duration:

28 d

Test conditions:

pH 6, 21.4 °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:

Co, Cr, Al

Loading of aqueous phase:

1 mg/L

Incubation duration:

24 h

Test conditions:

pH 8, 21.1 °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:

Co, Cr, Al

Loading of aqueous phase:

1 mg/L

Incubation duration:

7 d

Test conditions:

pH 8, 20.0 °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:

Co, Cr, Al

Loading of aqueous phase:

1 mg/L

Incubation duration:

28 d

Test conditions:

pH 8, 21.3 °C

Remarks on result:

other: < LOD

Details on results:

The analytical method was shown to be suitable for low content determination of cobalt, chromium and aluminium in aqueous samples due to the technique ICP-MS.
The analyzed range, from 0.1 to 200 µg/L, was found to be linear for cobalt, chromium and aluminium (correlation coefficient > 0.99).
The instrumental limit of detection (IDL) defined as the lowest calibration level, was 0.1 µg/L for cobalt, chromium and aluminium.
The limit of quantification (LOQ) of the method was 1 µg/L for cobalt and chromium, 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 cobalt, chromium and aluminium.
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 cobalt and chromium.
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.

Analytical results of the 28d full test at pH 6

Full test 28 days at 1 mg/L		Co (µg/L)	Cr (µg/L)	Al (µg/L)
Solution pH 6 T0h	Mean	n.d.	<1	<1
	SD	-	-	-
	RSD (%)	-	-	-
Solution pH 6 T2h	Mean	n.d.	n.d.	n.d.
	SD	-	-	-
	RSD (%)	-	-	-
Solution pH 6 T6h	Mean	n.d.	n.d.	2.6
	SD	-	-	0.3
	RSD (%)	-	-	13.4
Solution pH 6 T1d	Mean	n.d.	n.d.	1.4
	SD	-	-	0.2
	RSD (%)	-	-	14.1
Solution pH 6 T4d	Mean	n.d.	n.d.	3.4
	SD	-	-	0.5
	RSD (%)	-	-	13.8
Solution pH 6 T7d	Mean	n.d.	n.d.	3.0
	SD	-	-	0.3
	RSD (%)	-	-	10.0
Solution pH 6T15 d	Mean	n.d.	n.d.	5.8
	SD	-	-	1.1
	RSD (%)	-	-	18.1
Solution pH 6T21d	Mean	n.d.	n.d.	3.7
	SD	-	-	0.2
	RSD (%)	-	-	4.4
Solution pH 6 T28d	Mean	n.d.	n.d.	1.9
	SD	-	-	0.1
	RSD (%)	-	-	4.6

Abbreviations:

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

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

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

Analytical results of the 28d full test at pH 8

Full test 28 days at 1 mg/L		Co (µg/L)	Cr (µg/L)	Al (µg/L)
Solution pH 8 T0h	Mean	n.d.	<1	1.8
	SD	-	-	0.4
	RSD (%)	-	-	21.7
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 T15d	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 Co, Cr and Al).

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

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

Specificity

Cobalt, chromium and aluminium concentrations of blanks from each test medium were analyzed. Cobalt concentrations in blanks of the respective media were below the method LOD, while chromium and aluminium concentrations in blanks of the respective media were higher than the method LOD

 

Linearity and System Precision

The analysed range of Co, Cr and Al 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 Co analysis:

m (slope): 1.1959

q (intercept): 0.0012

R²(correlation): 0.9994

Parameters of linear calibration for Cr analysis:

m (slope): 0.8527

q (intercept): 0.0195

R²(correlation): 0.9992

Parameters of linear calibration for Al analysis:

m (slope): 0.0260

q (intercept): 0.0662

R²(correlation): 0.9992

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	Co (µg/L) (1)	Co Recovery (%)	Cr (µg/L) (1)	Cr Recovery (%)	Al (µg/L) (1)	Al Recovery (%)
Solution blank	n.d.	-	n.d.	-	n.d.	-
Spike L1	0.92	92.29	0.94	93.61	1.11	111.15
Spike L2	0.94	94.14	0.96	95.80	1.07	107.35
Spike L3	0.93	93.42	0.92	92.45	1.03	103.29
Mean value:	0.9	93.3	0.9	94.0	1.1	107.3
Standard deviation (SD):	0.01	0.93	0.02	1.70	0.04	3.93
Relative Standard deviation (RSD (%)):	1.0	1.0	1.8	1.8	3.7	3.7
Elution medium pH 6	Co (µg/L) (1)	Co Recovery (%)	Cr (µg/L) (1)	Cr Recovery (%)	Al (µg/L) (1)	Al Recovery (%)
Solution blank	n.d.	-	n.d.	-	n.d.	-
Spike H1	9.12	91.22	9.36	93.62	10.61	106.10
Spike H2	9.28	92.81	9.54	95.43	11.03	110.32
Spike H3	9.15	91.51	9.41	94.07	11.04	110.40
Mean value:	9.2	91.8	9.4	94.4	10.9	108.9
Standard deviation (SD):	0.08	0.85	0.09	0.94	0.25	2.46
Relative Standard deviation (RSD (%)):	0.9	0.9	1.0	1.0	2.3	2.3

(1) Mean of two determinations.

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

Repeatability and Recovery test: Test medium at pH 8

Elution medium pH 8	Co (µg/L) (1)	Co Recovery (%)	Cr (µg/L) (1)	Cr Recovery (%)	Al (µg/L) (1)	Al Recovery (%)
Solution blank	n.d.	-	n.d.	-	n.d.	-
Spike L1	0.91	91.47	0.93	92.97	1.04	103.51
Spike L2	0.91	91.05	0.95	95.00	1.01	100.56
Spike L3	0.88	88.25	0.93	93.42	1.04	103.79
Mean value:	0.9	90.3	0.9	93.8	1.0	102.6
Standard deviation (SD):	0.02	1.75	0.01	1.06	0.02	1.79
Relative Standard deviation (RSD (%)):	1.9	1.9	1.1	1.1	1.7	1.7
Elution medium pH 8	Co (µg/L) (1)	Co Recovery (%)	Cr (µg/L) (1)	Cr Recovery (%)	Al (µg/L) (1)	Al Recovery (%)
Solution blank	n.d.	-	n.d.	-	n.d.	-
Spike H1	8.74	87.39	9.14	91.43	11.23	112.32
Spike H2	9.05	90.46	9.49	94.85	11.52	115.24
Spike H3	8.95	89.47	9.34	93.43	11.78	117.83
Mean value:	8.9	89.1	9.3	93.2	11.5	115.1(*)
Standard deviation (SD):	0.16	1.57	0.17	1.72	0.28	2.75
Relative Standard deviation (RSD (%)):	1.8	1.8	1.8	1.8	2.4	2.4

(1) Mean of two determinations.

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

(*) Out value from the range of acceptability following guideline SANCO/3029/99 rev. 4 but considering the precision of the analytical method fixed at 10 % it can be acceptable.

Repeatability and Recovery test: Certified Reference Material analysis  

	Ratio Co/Ge	Co (µg/L)	Ratio Cr/Ge	Cr (µg/L)	Ratio Al/Ge	Al (µg/L)
Certified Reference Material A	18.7878	15.71	14.2271	16.66	0.9601	34.38
Certified Reference Material B	17.9231	14.99	13.7172	16.06	0.9314	33.28
Mean value(µg/L):	15.35		16.36		33.83
Standard deviation (SD):	0.51		0.42		0.78
Relative Standard deviation (RSD (%)):	3.3		2.6		2.3

Conclusions:

Transformation/dissolution of cobalt chromite blue green spinel was investigated 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:

28d-full test at pH 6 and 8
Full test 7 days at 1 mg/L and pH 6: <0.5 µg Co/L, <0.5 µg Cr/L and 3.0 ± 0.3 µg Al/L
Full test 7 days at 1 mg/L and pH 8: <0.5 µg Co/L, <0.5 µg Cr/L and <0.5 µg Al/L
Full test 28 days at 1 mg/L and pH 6: <0.5 µg Co/L, <0.5 µg Cr/L and 1.9 ± 0.1 µg Al/L
Full test 28 days at 1 mg/L and pH 8: <0.5 µg Co/L, <0.5 µg Cr/L and <0.5 µg Al/LL

The dissolved Co, Al, Cr concentrations were below 3 µg/L after 28 days at a loading of 1 mg/L, referring to a total solubility of < 0.3 %.
Thus, the extent to which the pigment can produce soluble available ionic and other metal-bearing species in aqueous media is limited.

Reference 2

Endpoint:

transformation / dissolution of metals and inorganic metal compounds

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2015-03-05 to 2015-04-14

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

The 28-day test with a loading of 1 mg/L was conducted at pH 6 and 8 instead of 5.5 and 8.5. / mass balance (%) after completion of the transformation test´ is missing / The within-vessel variation was not always < 10 % / The LOD should be lower

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:

yes

Remarks:

please refer to the field "Rationale for reliability incl. deficiencies" above

GLP compliance:

yes (incl. QA statement)

Remarks:

signed 2014-10-22

Type of method:

flask method

Type of test:

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

Mean dissolved conc.:

> 0.5 - < 1 µg/L

Element analysed:

Zn

Loading of aqueous phase:

1 mg/L

Incubation duration:

24 h

Test conditions:

pH 6.06, 21.2 °C

Remarks on result:

other: > LOD, < LOQ

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:

Zn

Loading of aqueous phase:

1 mg/L

Incubation duration:

7 d

Test conditions:

pH 6.06, 21.3 °C

Remarks on result:

other: > LOD, < LOQ

Key result

Type of test:

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

Mean dissolved conc.:

> 0.5 - < 1 mg/L

Element analysed:

Zn

Loading of aqueous phase:

1 mg/L

Incubation duration:

28 d

Test conditions:

pH 5.94, 21.1 °C

Remarks on result:

other: > LOD, < LOQ

Type of test:

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

Mean dissolved conc.:

> 0.5 - < 1 µg/L

Element analysed:

Zn

Loading of aqueous phase:

1 mg/L

Incubation duration:

24 h

Test conditions:

pH 7.91, 21.9 °C

Remarks on result:

other: > LOD, < LOQ

Key result

Type of test:

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

Mean dissolved conc.:

1.04 µg/L

Element analysed:

Zn

Loading of aqueous phase:

1 mg/L

Incubation duration:

7 d

Test conditions:

pH 7.94, 21.5 °C

Remarks on result:

other: S.D.:0.03 µg Zn/L

Key result

Type of test:

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

Mean dissolved conc.:

1.36 µg/L

Element analysed:

Zn

Loading of aqueous phase:

1 mg/L

Incubation duration:

28 d

Test conditions:

pH 7.96, 21.7 °C

Remarks on result:

other: S.D.: 0.03 µg Zn/L

Details on results:

Linearity:
- Correlation coefficient < 0.99; the range of zinc concentrations from 0.5 µg/L to 200 µg/L was found to be linear
- IDL: 0.5 µg/L (instrumental limit of detection (IDL) defined as the lowest calibration level)
- LOQ: 1 µg/L (limit of quantification (LOQ) of the method was defined as the lowest fortification level)
- LOD: 0.5 µg/L (limit of detection (LOD) of the method was defined as 50 % of the lowest fortification level)
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 cobalt and chromium.

Precision (Repeatability):
- RSD for all test media and fortification levels is < 20 %
Accuracy (Recovery):
- Individual recovery values are in the range from 70 % to 110 % with a mean between 80 % and 100 % for all tested media and fortification levels
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.

Analytical results of the 28d full test at pH 6

Full test 28 days at 1 mg/L		^64Zn (µg/L)
Solution pH 6 T0h	Mean	n.d.
	SD	-
	RSD (%)	-
Solution pH 6 T2h	Mean	n.d.
	SD	-
	RSD (%)	-
Solution pH 6 T6h	Mean	< 1
	SD	-
	RSD (%)	-
Solution pH 6 T24h	Mean	< 1
	SD	-
	RSD (%)	-
Solution pH 6 T4d	Mean	< 1
	SD	-
	RSD (%)	-
Solution pH 6 T7d	Mean	< 1
	SD	-
	RSD (%)	-
Solution pH 6T15 d	Mean	< 1
	SD	-
	RSD (%)	-
Solution pH 6T21d	Mean	< 1
	SD	-
	RSD (%)	-
Solution pH 6 T28d	Mean	< 1
	SD	-
	RSD (%)	-

SD: standard deviation

RSD (%): relative standard deviation %

n.d.: lower than the limit of detection (LOD) (0.5 µg Zn/L)

<1: lower than the limit of quantification (LOQ) (1 µg Zn/L) but higher than the limit of detection (LOD) (0.5 µg Zn/L)

Analytical results of the 28d full test at pH 8

Full test 28 days at 1 mg/L		^64Zn (µg/L)
Solution pH 8 T0h	Mean	n.d.
	SD	-
	RSD (%)	-
Solution pH 8 T2h	Mean	< 1
	SD	-
	RSD (%)	-
Solution pH 8 T6h	Mean	< 1
	SD	-
	RSD (%)	-
Solution pH 8 T24h	Mean	< 1
	SD	-
	RSD (%)	-
Solution pH 8 T4d	Mean	< 1
	SD	-
	RSD (%)	-
Solution pH 8 T7d	Mean	1.04
	SD	0.03
	RSD (%)	2.8
Solution pH 8 T15d	Mean	1.17
	SD	0.02
	RSD (%)	1.5
Solution pH 8 T21d	Mean	1.28
	SD	0.04
	RSD (%)	3.0
Solution pH 8 T28d	Mean	1.36
	SD	0.03
	RSD (%)	2.2

SD: standard deviation

RSD (%): relative standard deviation %

n.d.: lower than the limit of detection (LOD) (0.5 µg Zn/L)

<1: lower than the limit of quantification (LOQ) (1 µg Zn/L) but higher than the limit of detection (LOD) (0.5 µg Zn/L)

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

 

Linearity and System Precision

The analysed range of Zn concentrations, from 0.5 µg/L to 200 µg/L, was found to be linear (correlation coefficient > 0.99). 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 0.0 - 5.0 µg/L, from 1 - µg/l and from 0.0 to 200 µg/L.

Parameters of linear calibration from 0.0 - 5.0 µg Zn/L:

m (slope): 0.2951

q (intercept): 0.3599

R²(correlation): 0.9983

Parameters of linear calibration for Cr analysis:

m (slope): 0.8527

q (intercept): 0.0195

R²(correlation): 0.9992

Parameters of linear calibration for Al analysis:

m (slope): 0.0260

q (intercept): 0.0662

R²(correlation): 0.9992

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: Spike Low and High, buffer pH 6

Buffer at pH 6	^64Zn in control (µg/L)	^64Zn in sample (µg/L)	^64Zn (µg/L)*	^64Zn fortification level (µg/L)	Recovery (%)	Mean Recovery (%)
Spike Low A1	0.41	1.40	0.99	1.00	99.35	99.52
Spike Low A2	0.37	1.37	1.00	1.00	99.70
Spike Low B1	0.35	1.34	0.99	1.00	99.24	99.29
Spike Low B2	0.39	1.38	0.99	1.00	99.34
Spike Low C1	0.36	1.34	0.99	1.00	98.72	98.91
Spike Low C2	0.38	1.38	0.99	1.00	99.10
Mean value					99.24	99.24
Standard deviation (SD)					0.32	0.31
Relative Standard deviation (RSD (%))					0.33	0.31
Spike High A1	0.41	10.28	9.87	10.00	98.73	97.65
Spike High A2	0.37	10.03	9.66	10.00	96.56
Spike High B1	0.35	10.18	9.83	10.00	98.25	98.21
Spike High B2	0.39	10.20	9.82	10.00	98.17
Spike High C1	0.36	10.14	9.79	10.00	97.85	97.48
Spike High C2	0.38	10.09	9.71	10.00	97.10
Mean value					97.78	97.78
Standard deviation (SD)					0.80	0.38
Relative Standard deviation (RSD (%))					0.82	0.39

* These values were calculated subtracting the relevant control sample value, in order to consider the contribution of the test medium

 

Repeatability and Recovery test: Spike Low and High, buffer pH 8

Buffer at pH 6	^64Zn in control (µg/L)	^64Zn in sample (µg/L)	^64Zn (µg/L)*	^64Zn fortification level (µg/L)	Recovery (%)	Mean Recovery (%)
Spike Low A1	0.44	1.40	0.96	1.00	96.39	96.97
Spike Low A2	0.42	1.39	0.98	1.00	97.54
Spike Low B1	0.43	1.39	0.97	1.00	96.74	97.08
Spike Low B2	0.42	1.39	0.97	1.00	97.42
Spike Low C1	0.41	1.38	0.97	1.00	96.82	97.07
Spike Low C2	0.42	1.40	0.97	1.00	97.32
Mean value					97.04	97.04
Standard deviation (SD)					0.45	0.06
Relative Standard deviation (RSD (%))					0.47	0.06
Spike High A1	0.44	10.28	9.84	10.00	98.36	97.76
Spike High A2	0.42	10.13	9.72	10.00	97.16
Spike High B1	0.43	10.18	9.75	10.00	97.54	98.23
Spike High B2	0.42	10.31	9.89	10.00	98.93
Spike High C1	0.41	10.28	9.87	10.00	98.71	99.15
Spike High C2	0.42	10.38	9.96	10.00	99.58
Mean value					98.38	98.38
Standard deviation (SD)					0.90	0.70
Relative Standard deviation (RSD (%))					0.91	0.72

* These values were calculated subtracting the relevant control sample value, in order to consider the contribution of the test medium

 

Repeatability and recovery test: Certified reference material

Buffer at pH 6	Ratio^64Zn/^72Ge	^64Zn (µg/L)
Certified reference material A	9.3198	41.19
Certified reference material B	9.0728	40.00
Certified reference material C	9.3524	41.35
Mean value		40.85
Standard deviation (SD)		0.74
Relative Standard deviation (RSD (%))		1.8
Minimum accepted value (µg/L)		39.7
Maximum accepted value (µg/L)		49.3
Buffer at pH 8	Ratio^64Zn/^72Ge	^64Zn (µg/L)
Certified reference material A	9.0387	40.40
Certified reference material B	8.9846	40.14
Certified reference material C	8.9203	39.82
Mean value		40.12
Standard deviation (SD)		0.29
Relative Standard deviation (RSD (%))		0.7
Minimum accepted value (µg/L)		39.7
Maximum accepted value (µg/L)		49.3

Conclusions:

The analytical method was shown to be suitable for low content determination of zinc in aqueous samples due to the technique ICP-MS.
The analyzed range of zinc concentrations from 0.5 to 200 µg/L, was found to be linear (correlation coefficient > 0.99).
The instrumental limit of detection (IDL) defined as the lowest calibration level, was 0.5 µg/L for zinc
The limit of quantification (LOQ) of the method was 1µg/L for zinc 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 zinc.
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 zinc
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.

28d-full test at pH 6 and 8
Full test 7 days at 1 mg/L and pH 6: < 1 µg Zn/L
Full test 7 days at 1 mg/L and pH 8: 1.04 µg Zn/L
Full test 28 days at 1 mg/L and pH 6: < 1 µg Zn/L
Full test 28 days at 1 mg/L and pH 8: 1.36 µg Zn/L

Description of key information

The solubility of cobalt chromite blue green spinel is < 0.4 wt% at a 1mg/L loading and ph 6and 8. A GLP-conform transformation/dissolution test with a loading of 1 mg/L at pH6 and ph8 over 28 days, revealed higher dissolution of aluminium at pH 6 and a higher dissolution of zinc at pH8.

Transformation/dissolution at a loading of 1 mg/L at pH6 and 8 after 7 and 28 days resulted in dissolved cobalt and chromium concentrations below LOD. The dissolved aluminium concentrations at pH6 were of 3.0 µg/L and 1.09 µg/L after 7 and 28 days, respectively (Pardo Martinez, 2013). The dissolved zinc concentrations at pH8 were of 1.04 µg/L and 1.36 µg/L after 7 and 28 days, respectively (Pardo Martinez, 2015).

The particle size of the tested sample (BET surface area 1.5 m2/g) is representative for the particle size on the market. Thus, the extent to which "cobalt chromite blue green spinel" can produce soluble available ionic and other metal-bearing species in aqueous media is limited.