Zirconium iron pink zircon

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:

2012-03-09 to 2012-06-21

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

deviations from the guideline, which do not effect the validity of the study: (a) the 28-day test with a loading of 1 mg/L was conducted at a pH 8 instead of 8.5. (b) `mass balance (%) after completion of the transformation test´ is missing (c) the between-vessel variation in the 7 d-test, loading of 100 mg/L, at pH 6 after 6 h and after 1 d was not less than the 20 %.

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:

2001

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

Remarks:

transformation / dissolution

Type of test:

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

Mean dissolved conc.:

< 0.5 µg/L

Element analysed:

Fe, Zr

Loading of aqueous phase:

100 mg/L

Incubation duration:

7 d

Test conditions:

pH: 6, Temp.: 19.9 °C

Remarks on result:

other: < LOD (0.5 µg/L)

Key result

Type of test:

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

Mean dissolved conc.:

2.4 µg/L

Element analysed:

Fe

Loading of aqueous phase:

100 mg/L

Incubation duration:

7 d

Test conditions:

pH: 8, Temp.: 20 °C

Remarks on result:

other: S.D.: +/- 0.37 µg/L

Key result

Type of test:

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

Mean dissolved conc.:

2.17 µg/L

Element analysed:

Zr

Loading of aqueous phase:

100 mg/L

Incubation duration:

7 d

Test conditions:

pH 8, Temp.: 20 °C

Remarks on result:

other: S.D.: +/- 0.34 µg/L

Type of test:

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

Mean dissolved conc.:

3.5 µg/L

Element analysed:

Fe

Loading of aqueous phase:

1 mg/L

Incubation duration:

24 h

Test conditions:

pH 8, Temp.: 20.0 °C

Remarks on result:

other: S.D.: +/- 0.4 µg/L

Type of test:

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

Mean dissolved conc.:

< 0.5 µg/L

Element analysed:

Zr

Loading of aqueous phase:

1 mg/L

Incubation duration:

24 h

Test conditions:

pH 8, Temp.: 20.0 °C

Remarks on result:

other: < LOD (0.5 µg/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:

Fe, Zr

Loading of aqueous phase:

1 mg/L

Incubation duration:

7 d

Test conditions:

pH: 8, Temp.: 21.1 °C

Remarks on result:

other: < LOD (0.5 µg/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:

Fe, Zr

Loading of aqueous phase:

1 mg/L

Incubation duration:

28 d

Test conditions:

pH. 8, Temp.: 21.2 °C

Remarks on result:

other: < LOD (0.5 µg/L)

Details on results:

The analytical method was shown to be suitable for low content determination of zirconium and iron 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 zirconium and iron (correlation coefficient > 0.99).
The instrumental limit of detection (IDL) defined as the lowest calibration level, was 0.1 µg/L for zirconium and iron.
The limit of quantification (LOQ) of the method was 1 µg/L for zirconium and iron, 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 zirconium and iron.
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 zirconium and iron.
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 7d-full test at pH 6

Full test 7 days at 100 mg/L		Fe (µg/L)	Zr (µg/L)
Solution pH 6 T0h	Mean	6.93	n.d.
	SD	0.33	-
	RSD (%)	4.8	-
Solution pH 6 T2h	Mean	n.d.	2.93
	SD	-	0.16
	RSD (%)	-	5.3
Solution pH 6 T6h	Mean	n.d.	1.34
	SD	-	0.34
	RSD (%)	-	25.3(*)
Solution pH 6 T1d	Mean	n.d.	<1
	SD	-	-
	RSD (%)	-	-
Solution pH 6 T4d	Mean	n.d.	n.d.
	SD	-	-
	RSD (%)	-	-
Solution pH 6 T7d	Mean	n.d.	n.d.
	SD	-	-
	RSD (%)	-	-

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

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

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

(*)The between-vessel variation after 6 hours was not less than the 20 % recommended by OECD Series No. 29.

 Summary results for the 7d-full test at pH 8

Full test 7 days at 100 mg/L		Fe (µg/L)	Zr (µg/L)
Solution pH 8 T0h	Mean	5.67	n.d.
	SD	0.48	-
	RSD (%)	8.4	-
Solution pH 8 T2h	Mean	1.46	4.12
	SD	0.23	0.36
	RSD (%)	15.6	8.7
Solution pH 8 T6h	Mean	1.85	3.72
	SD	0.36	0.24
	RSD (%)	19.4	6.4
Solution pH 8 T1d	Mean	2.05	3.73
	SD	0.64	0.30
	RSD (%)	31.4(*)	7.9
Solution pH 8 T4d	Mean	2.84	2.80
	SD	0.25	0.21
	RSD (%)	9.0	7.4
Solution pH 8 T7d	Mean	2.40	2.17
	SD	0.37	0.34
	RSD (%)	15.6	15.9

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

(*)The between-vessel variation after 1 day was not less than the 20 % recommended by OECD Series No. 29.

  

 

Summary results for the 28d-full test at pH 8

Full test 28 days at 1 mg/L		Fe (µg/L)	Zr (µg/L)
Solution pH 8 T0h	Mean	n.d.	n.d.
	SD	-	-
	RSD (%)	-	-
Solution pH 8 T2h	Mean	n.d.	n.d.
	SD	-	-
	RSD (%)	-	-
Solution pH 8 T6h	Mean	1.7	n.d.
	SD	0.1	-
	RSD (%)	6.7	-
Solution pH 8 T1d	Mean	3.5	n.d.
	SD	0.4	-
	RSD (%)	11.8	-
Solution pH 8 T4d	Mean	n.d.	n.d.
	SD	-	-
	RSD (%)	-	-
Solution pH 8 T7d	Mean	n.d.	n.d.
	SD	-	-
	RSD (%)	-	-
Solution pH 8 T14d	Mean	n.d.	n.d.
	SD	-	-
	RSD (%)	-	-
Solution pH 8 T21d	Mean	n.d.	n.d.
	SD	-	-
	RSD (%)	-	-
Solution pH 8 T28d	Mean	n.d.	n.d.
	SD	-	-
	RSD (%)	-	-

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

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

m (slope): 0.6670

q (intercept): 0.5729

R²(correlation): 0.9999

Parameters of linear calibration for Zr analysis of solutions fromthe 28d-full test:

m (slope): 0.0890

q (intercept): 0.0062

R²(correlation): 0.9999

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

 

Specificity

Zirconium and iron concentrations of blanks from each test medium were analyzed. Zirconium concentrations in blanks of the respective media were below the method LOD, while iron concentrations in blanks of the respective media were higher than the method LOQ.

 

Linearity and System Precision

The analysed range of Zr and Fe concentrations, from 0.1µg/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): 0.6400

q (intercept): 0.4255

R²(correlation): 0.9990

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

m (slope): 0.0850

q (intercept): 0.0029

R²(correlation): 0.9993

 

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	6.2	82.7 %
	10 µg/L	8.8 µg/L	1.6	87.6%
pH 8	1 µg/L	0.7 µg/L	3.7	74.4 %
	10 µg/L	8.9 µg/L	1.0	88.8 %

Recovery (Zr)

Test Medium	Spike add	Mean Found	RSD (%)	Recovery  Mean
pH 6	1 µg/L	0.7 µg/L	5.6	74.9 %
	10 µg/L	8.1 µg/L	3.4	81.2 %
pH 8	1 µg/L	0.7 µg/L	2.2	71.7 %
	10 µg/L	8.5 µg/L	1.7	84.8 %

Repeatability and Recovery test: Test medium at pH 6 

Elution medium pH 6	Fe (µg/L) (1)	Fe Recovery (%)	Zr (µg/L) (1)	Zr Recovery (%)
Buffer blank	n.d.	-	n.d.	-
Spike L1	0.79	79.31	0.71	70.79
Spike L2	0.89	88.61	0.79	79.24
Spike L3	0.80	80.31	0.75	74.57
Mean value:	0.8	82.7	0.7	74.9
Standard deviation (SD):	0.05	5.10	0.04	4.23
Relative Standard deviation (RSD (%)):	6.2	6.2	5.6	5.6
Elution medium pH 6	Fe (µg/L) (1)	Fe Recovery (%)	Zr (µg/L) (1)	Zr Recovery (%)
Buffer blank	n.d.	-	n.d.	-
Spike H1	8.85	88.48	8.38	83.81
Spike H2	8.83	88.31	8.13	81.32
Spike H3	8.60	86.00	7.83	78.34
Mean value:	8.8	87.6	8.1	81.2
Standard deviation (SD):	0.14	1.38	0.27	2.74
Relative Standard deviation (RSD (%)):	1.6	1.6	3.4	3.4

(1) Mean of two determinations.

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

Repeatability and Recovery test: Test medium at pH 8 

Elution medium pH 8	Fe (µg/L) (1)	Fe Recovery (%)	Zr (µg/L) (1)	Zr Recovery (%)
Buffer blank	n.d.	-	n.d.	-
Spike L1	0.78	77.59	0.71	70.54
Spike L2	0.72	72.36	0.73	73.41
Spike L3	0.73	73.31	0.71	71.00
Mean value:	0.7	74.4	0.7	71.7
Standard deviation (SD):	0.03	2.79	0.02	1.54
Relative Standard deviation (RSD (%)):	3.7	3.7	2.2	2.2
Elution medium pH 8	Fe (µg/L) (1)	Fe Recovery (%)	Zr (µg/L) (1)	Zr Recovery (%)
Buffer blank	n.d.	-	n.d.	-
Spike H1	8.81	88.10	8.31	83.15
Spike H2	8.84	88.44	8.55	85.46
Spike H3	8.97	89.72	8.57	85.74
Mean value:	8.9	88.8	8.5	84.8
Standard deviation (SD):	0.09	0.85	0.14	1.42
Relative Standard deviation (RSD (%)):	1.0	1.0	1.7	1.7

(1) Mean of two determinations.

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

Repeatability and Recovery test: Certified Reference Material analysis

	Ratio Fe/Ge	Fe (µg/L)	Ratio(*) Zr/In	Zr(*) (µg/L)
Certified Reference Material A	16.0269	24.38	-	-
Certified Reference Material B	16.1946	24.64	-	-
Certified Reference Material C	16.3613	24.90	-	-
Mean value (µg/L):	24.64		-
Standard deviation (SD):	0.26		-
Relative Standard deviation (RSD (%)):	1.1		-

(*) Note: The Certified Reference Material does not report a certified value for zirconium.

 

Conclusions:

The transformation/dissolution of zirconium iron pink zircon 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 pH 6: < 0.5 µg Fe and Zr/L
Full test 7 days at 100 mg/L and pH 8: 2.4 µg Fe/L ± 0.37 and 2.17 µg Zr/L ± 0.34

Full test 28 days at 1 mg/L and pH 8: < 0.5 µg Fe and Zr/L

The dissolved Fe and Zr concentrations were below 2.5 µg/L respectively, even at the highest loading of 100 mg/L, referring to a solubility of < 0.005 %. Thus, the extent to which " zirconium iron pink zircon" can produce soluble available ionic and other metal-bearing species in aqueous media is limited.

Description of key information

The solubility of Zirconium zircon with encapsulated hematite is < 0.005 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 Zr and Fe concentration at pH8 after 7 days were 2.17 mircog/L and 2.4 microg/L, respectively. Transformation/dissolution at a loading of 1 mg/L at pH8 over 28 days resulted in dissolved Zr and Fe concentrations below < LOD (0.5 mircog/L) after 7 and 28 days (Pardo Martinez, 2013). The particle size of the tested sample (BET surface area 1.3 m2/g) is representative for the particle size on the market. Thus, the extent to which " Zirconium zircon with encapsulated hematite" can produce soluble available ionic and other metal-bearing species in aqueous media is limited.