Trisodium hydrogen ethylenediaminetetraacetate

Water solubility

Link to relevant study record(s)

Reference

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

09 May - 14 Aug 2018

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Qualifier:

according to guideline

Guideline:

EU Method A.6 (Water Solubility)

GLP compliance:

yes (incl. QA statement)

Remarks:

Hess. Ministerium für Umwelt, Klimaschutz, Landwirtschaft und Verbraucherschutz, Wiesbaden, Germany

Type of method:

flask method

Specific details on test material used for the study:

Storage conditions: room temperature

Water solubility:

>= 201.3 - <= 212.9 g/L

Conc. based on:

test mat. (dissolved fraction)

Remarks:

result estimated from second preliminary test

pH:

>= 7.2 - <= 8.7

Remarks on result:

other: Temp = 24.6 to 28.4 °C

Results
Preliminary test
The first preliminary test at room temperature showed, that the water solubility of the test item was between 65.1 g/L and 173.5 g/L. The observations of the preliminary test are summarized in 3.

Table 3: First preliminary test for the water solubility

Amount of test item [mg]	Total volume of added water [mL]	Ultrasonic bath [min]	Remark
104.11	0.1	--	not dissolved
	0.6	--	not dissolved
	1.6	3	dissolved

The solubility of the test item in water at room temperature was estimated to be > 65.1 g/L and < 173.5 g/L. Therefore, the flask method was performed.

The first preliminary test is not very exact, because of the small volumes of water. It is sufficient for the decision, which method has to be used in the main test.

Due to the analytical problems, a further preliminary test with higher amounts of water and test item was performed:

Table4: Second preliminary test for the water solubility

Total amount of added test item [g]	Volume of water [mL]	Stirring time at 30 °C [h]	Remark
8.01	45.0	73	dissolved
8.53		24	dissolved
9.06		26	dissolved
9.58		74	not dissolved

The solubility of the dried solid test item in water could be estimated from this preliminary test to be between 201.3 and 212.9 g/L

 

Main Test (flask method)

For the main test three flasks were prepared with an amount of test item and water, and one flask only with water. After stirring and centrifugation the aqueous phases were measured by means of HPLC. The pH value of the aqueous phases was between 8.5 and 8.7.

The measurements of the flasks showed modified chromatograms of the test item. During the calibration and the validation of the analytical method with the dried solid test item, the chromatogram showed a monomodal signal of the test item at a retention time of 1.5 – 2.2 min. The measurements of the flasks showed bimodal signals at a retention time of 2.3 – 2.8 min. Furthermore, the integration of the signals of the flasks resulted in much to low water solubility values.

For a verification of the analytical method, different freshly prepared standards (test item in double distilled water) were measured. Here, the concentrations of the solutions could not be found in the HPLC (approx. 70 mg/L instead of 418 mg/L). The signals were monomodal at a retention time of 2 – 2.6 min.

After that, a HPLC-measurement of the original liquid test item (20% -ETA-solution, pH 7.2) was performed, which showed a very broad signal at a retention time of 1.8 – 5.2 min.

In a next step we checked the HPLC-apparatus with a standard substance (caffeine). These measurements showed, that the apparatus worked correctly.

Nevertheless, we changed the HPLC-column and also the deuterium lamp and measured the test item samples again, which resulted in the same chromatograms. Thus, general problems with the HPLC-apparatus can be excluded.

Since, the substance EDTA has different dissociation constants, it can be assumed, that the test item in water with a pH-value of approx. 8 exists in different dissociation levels, which results in a bad recovery of the test item.

In summary, the HPLC (with UV-detection) is no suitable analytical method for the determination of the concentration of the test item in water.

Thus, the water solubility can only be estimated based on the second preliminary test to 201.3 – 212.9 g/L.

 

Conclusion:
According toOECD Test Guideline 105 (1995) and Regulation EC No. 440/2008 Method A.6. the water solubility at ambient temperature (24.6 to 28.4 °C) and a pH value of 7.2 to 8.7 of the dried solid test item ETALösung 181 / TRISODIUM EDTA SOLUTION 20% can be estimated to: 201.3 – 212.9 g/L

 

Description of key information

201.3 - 212.9 g/L at ambient temperature at pH value of 7.2 to 8.7 (OECD 105, Estimation based on preliminary test method)

Key value for chemical safety assessment

Water solubility:

212.9 g/L

at the temperature of:

20 °C

Additional information

According to OECD Test Guideline 105 (1995) and Regulation EC No. 440/2008 Method A.6. the water solubility at ambient temperature (24.6 to 28.4 °C) and a pH value of 7.2 to 8.7 of the test item can be estimated to 201.3 – 212.9 g/L

Based on analytical problems within the main test the final result was derived from the pretest.