Gadolinium trinitrate

Water solubility

Link to relevant study record(s)

Reference

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From 22 September 2014 to 24 February 2015

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EU Method A.6 (Water Solubility)

Deviations:

no

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

other: preliminary estimate of solubility by visual judgement with an investigation of the influence of pH variations

Key result

Water solubility:

>= 1 444 - < 1 466 g/L

Conc. based on:

test mat.

Temp.:

20 °C

pH:

>= -0.42 - <= -0.35

Remarks on result:

other: The test item was completely dissolved at 1444 g/L while precipitation was observed at 1466 g/L.

Water solubility:

1 407 g/L

Conc. based on:

test mat.

Temp.:

19.3 °C

pH:

4.94

Remarks on result:

other: The test item partially precipitated and some part of the substance was dissolved at pH=ca. 5.

Temp.:

18.2 °C

pH:

7.3

Remarks on result:

other: A significant impact of pH (at 7.30) was observed on solubility; the added test item was considered entirely precipitated. No maximum solubility could be determined.

Details on results:

Due to the high solubility observed during the assay without pH adjustment (pH close to 0), no definitive test was conducted. The experiments intended to investigate the pH effect were stopped after reaching the pH of 11.32 where the added test item was entirely precipitated.

After a preliminary assay, the maximum solubility of gadolinium trinitrate in demineralised water was determined to be between 1444 and 1466 g/L at ca. 20°C. The pH of the solution was between -0.42 to -0.35. The influence of a pH increase to ca. 5 was then investigated by adding sodium hydroxide to the solution of gadolinium trinitrate of ca. 1444 g/L. After adjustment to pH = 4.94, gadolinium trinitrate was partially dissolved at a concentration of 1407 g/L, taking the volume of sodium hydroxide added into account.

The influence of pH increase was further investigated by adding sodium hydroxide to reach a pH = 7.30. The test item was considered as entirely precipitated at this pH.

After adjustment of the pH of the solution to 11.32 using sodium hydroxide, the entire test item was also precipitated.

Therefore, it can be concluded that increasing the pH will lower the water solubility, no maximum solubility could be determined at pH 7 and pH 9.

Conclusions:

The substance is concluded to be very soluble in water with a maximum solubility between 1444 and 1466 g/L (pH between -0.42 to -0.35) at 20°C. The maximum solubility did not significantly change when increasing the pH to approximately 5. At higher pH (from at least pH = 7.30), the test item was considered as entirely precipitated.

Executive summary:

The water solubility of gadolinium trinitrate was investigated in compliance with GLP and according to the preliminary test as specified in EU A.6 method and OECD test guideline 105. The influence of pH variations was also investigated. Gadolinium trinitrate was determined to be very soluble in water with a maximum solubility in the range of 1444 to 1466 g/L, at 20°C and pH 0 (between -0.35 and -0.42). The maximum solubility did not significantly change when increasing the pH to approximately 5. It is important to note that the solubility was significantly decreased when the pH was adjusted to environmentally relevant values due to precipitation of the test item (from at least pH = 7.30).

Description of key information

Gadolinium trinitrate was determined to be very soluble in water with a maximum solubility in the range of 1444 to 1466 g/L, at 20°C and pH 0 (between -0.35 and -0.42). It is important to note that the solubility was significantly decreased when the pH was adjusted to environmentally relevant values due to complete precipitation of the test item (from at least pH = 7.30).

Key value for chemical safety assessment

Water solubility:

1 455 g/L

at the temperature of:

20 °C

Additional information

An experimental study of reliability 1 according to Klimisch, performed in compliance with GLP and according to the preliminary test as specified in EU method A.6 and OECD Guideline 105, was selected as a key study.

Gadolinium trinitrate was determined to be very soluble in water with a maximum solubility in the range of 1444 to 1466 g/L, at 20°C and pH 0 (between -0.35 and -0.42). The maximum solubility did not significantly change when increasing the pH to approximately 5. It is important to note that the solubility was significantly decreased when the pH was adjusted to environmentally relevant values due to precipitation of the test item (from at least pH = 7.30).