Iron titanium pseudobrookite

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:

2016-01-25 to 2016-03-23

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

the pH should be between 5.5 and 8.5 instead of 6 and 8, three instead of five replicates were tested twice insted of triple, the temperature differ more than 2 °C in the range of 20 - 25 °C.

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

Deviations:

yes

Remarks:

the pH should be between 5.5 and 8.5 instead of 6 and 8, three instead of five replicates were tested twice insted of triple, the temperature differ more than 2 °C in the range of 20 - 25 °C.

Qualifier:

according to guideline

Guideline:

other: EEC guideline SANCO/3029/99

Version / remarks:

rev. 4 dated 11/07/00

GLP compliance:

yes (incl. QA statement)

Remarks:

signed 2014-10-22

Type of method:

other: transformation / dissolution

Type of test:

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

Element analysed:

56Fe, 47Ti, 27Al

Loading of aqueous phase:

1 mg/L

Incubation duration:

28 d

Test conditions:

pH 6; agitation at 100 rpm; room temperature

Remarks on result:

not determinable

Remarks:

lower than the method Limit of Detection (LOD = 0.5 µg/L for Fe, Ti and Al)

Type of test:

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

Element analysed:

56 Fe, 47Ti, 27Al

Loading of aqueous phase:

1 mg/L

Incubation duration:

28 d

Test conditions:

pH 8; agitation at 100 rpm; room temperature

Remarks on result:

not determinable

Remarks:

lower than the method Limit of Detection (LOD = 0.5 µg/L for fe, Ti, Al)

Details on results:

The within-vessel variation and the between-vessel variation were less than 10% and less than 20 %, respectively, in accordance with OECD Series No. 29.
According to the SANCO/3029/99 rev. 4 guideline, the RSD are lower than 20 % for all tested media and fortification levels.
According to the SANCO/3029/99 rev. 4 guideline, the individual recovery values are in the range from 70 to 110 % with a mean between 80 to 100 % for all tested media and fortification levels.

Linearity

The nominal range of Iron, Titanium and Aluminium concentrations, from 0.50 µg/L to 200.00 µg/L, was found to be linear (correlation coefficient > 0.99).

The instrumental limit of detection (I.D.L.) defined as the lowest calibration level, was 0.5 µg/L for Iron, Titanium and Aluminium.

The limit of quantification (L.O.Q.) of the method was fixed at 1 µg/L, defined as the lowest fortification level.

The limit of detection (L.O.D.) of the method, defined as 50% of the lowest fortification level, was 0.5 µg/L.

Iron, Titanium and Aluminium concentrations lower than the L.O.D. were classified as not detected (n.d.).

Repeatability (Precision) and Accuracy (Recovery)

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 0.50 µg/L to 200.00 µg/L.

For precision, the SANCO/3029/99 rev. 4 guideline requires an RSD to be lower than 20 % for all tested media and fortification levels.

For accuracy, the SANCO/3029/99 rev. 4 guideline requires individual recovery values in the range from 70 to 110 % with a mean between 80 to 100 % for all tested media and fortification levels.

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.

From data obtained, these criteria were fulfilled and therefore precision and accuracy of the analytical method is acceptable.

For each test medium an ICP-MS sequence with working standard solutions, Control, Spike Low, Spike High solution samples and Certified Reference Material samples was performed.

Mean recovery of fortified samples in two artificial media at pH 6 and pH 8

	Artifical media pH 6	Artifical media pH 8
Fe spiked low (1 µg/L)	94.91 % ± 0.64 %	89.01 % ± 0.22 %
Fe spiked high (10 µg/L)	98.04 % ± 0.68 %	91.64 % ± 1.29 %
Ti spiked low (1 µg/L)	89.02 % ± 1.54 %	85.48 % ± 1.01 %
Ti spiked high (10 µg/L)	96.99 % ± 0.79 %	93.85 % ± 1.27 %
Al spiked low (1 µg/L)	85.63 % ± 0.25 %	84.54 % ± 0.63 %
Al spiked high (10 µg/L)	92.15 % ± 1.53 %	92.46 % ± 0.54 %

Temperature, pH and dissolved oxygen after in two artificial media at pH 6 and pH 8

Media	Temperature	pH	Dissolved oxygen
Artificial media pH 6	≥ 21.0 °C ≤ 25.1 °C	≥ 5.936 ≤ 6.22	≥ 80.1 % ≤ 82.8 %
Artificial media pH 8	≥ 20.9 °C ≤ 25.1 °C	≥ 7.842 ≤ 8.070	≥ 80.1 % ≤ 82.4 %

Conclusions:

The transformation/dissolution of pseudobrookite was determined according to OECD Series on Testing and Assessment No. 29 (ENV/JM/MONO(2001)9) and EEC guideline SANCO/3029/99 rev. 4 dated 11/07/00. A full transformation/dissolution test with a loading of 1 mg/L in two artificial media (pH 6 and pH 8) agitated at 100 rpm over 28 days at room temperature was conducted. The dissolved concentrations of iron, titanium and aluminium were lower than the LOD (0.5 µg/L) and therefore not determinable.

Description of key information

A full transformation/dissolution test with a loading of 1 mg/L in two artificial media (pH 6 and pH 8) agitated at 100 rpm over 28 days at room temperature was conducted. The dissolved concentrations of iron, titanium and aluminium were lower than the LOD (0.5 µg/L) and therefore not determinable.