Guanidinium chloride

Hydrolysis

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

28 September 1998 to 2 December 1998

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 111 (Hydrolysis as a Function of pH)

Deviations:

yes

Remarks:

- The pre-test observation period for the hydrolysis was 7 days instead of 5 days. As also in 7 days no significant hydrolysis occurred, it can be assumed that also in 5 days no hydrolysis occurred.

Qualifier:

according to guideline

Guideline:

EU Method C.7 (Degradation: Abiotic Degradation: Hydrolysis as a Function of pH)

Deviations:

yes

Remarks:

- The pre-test observation period for the hydrolysis was 7 days instead of 5 days. As also in 7 days no significant hydrolysis occurred, it can be assumed that also in 5 days no hydrolysis occurred.)

GLP compliance:

yes

Remarks:

according to “The OECD-Principles of Good Laboratory Practice”, OECD Environment Health and Safety Publications. Series on Principles of Good Laboratory Practice and Compliance Monitoring No. 1, Paris 1998

Radiolabelling:

no

Analytical monitoring:

yes

Details on sampling:

- Sampling intervals for the parent products: 0, 1.0, 2.0, 3.0, 46.0, 167.5, 171.5 and 171.75 h
- Sampling method: 1 mL solution was taken from the incubation flask and diluted 1 : 10 with deionized water.
- Sampling intervals/times for pH measurements: 0 and 171.5 or 171.75 h

Buffers:

- pH: Nominal 4, 7 and 9; actual at 24 °C 4.10, 7.00 and 8.95; actual at 50 °C 4.06, 6.97 and 8.77
Buffer pH 4: 500 mL 0.1 mol/L potassium hydrogenphthalate (E. Merck, Darmstadt, Germany, Art: 1.04874, purity: >99.9 %) and 4 mL 0.1 mol/L sodium hydroxide (E. Merck, Art: 6498, purity: >99.0 %) filled up to 1000 mL with deionized water.
Buffer pH 7: 500 mL 0.1 mol/L potassium dihydrogenphosphate (E.Merck, Art: 4873, purity: >99.5 %) and 296.3 mL 0.1 mol/L sodium hydroxide filled up to 1000 mL with deionized water.
Buffer pH 9: 500 mL 0.1 mol/L boric acid (E. Merck, Art: 165, purity: >99.8 %) in 0.1 mol/L potassium chloride (E. Merck, Art: 4936, purity: >99.5 %) and 213 mL 0.1 mol/L sodium hydroxide filled up to 1000 mL with deionized water.
Each buffer solution was degassed with helium for ten minutes and kept one hour at the test temperature 50 "C before use. The deionized water was boiled for 15 minutes and kept in a refrigerator before use.

Details on test conditions:

TEST MEDIUM
- Volume used/treatment: 100 mL (in the solely performed) pre-test
- Lighting: The Solutions were kept in the dark.
- Kind and purity of water: Deionised water, boiled for 15 minutes and kept in a refrigerator before use
- Preparation of test medium: In the (solely performed) pre-test portions of 180 mg of the test substance were weighed in flasks and dissolved in about 100 mL of the appropriate buffer to give solutions of 0.01 mol/L as requested by the guidelines.
OTHER TEST CONDITIONS
- Adjustment of pH: The actual pH of the samples (buffer plus test substance) at the begin of the hydrolysis were 4.9, 7.3 and 9.0 instead of the required values of 4.0, 7.0 and 9.0. This shifts were assumed to be caused by the test substance. No corrections were made

Duration:

171.5 h

pH:

4.9

Temp.:

50 °C

Initial conc. measured:

1.77 g/L

Duration:

171.5 h

pH:

7.3

Temp.:

50 °C

Initial conc. measured:

1.79 g/L

Duration:

171.5 h

pH:

9

Temp.:

50 °C

Initial conc. measured:

1.62 g/L

Number of replicates:

One replicate per pH was used in the pre-test and no main test was required.

Positive controls:

no

Negative controls:

no

Preliminary study:

In none of the buffer solutions at pH 4, 7 and 9 at 50 °C more than 10 % of the test substance hydrolysed within 5 days.

Transformation products:

no

Key result

pH:

4.06

Temp.:

25 °C

DT50:

> 1 yr

Type:

(pseudo-)first order (= half-life)

Remarks on result:

hydrolytically stable based on preliminary test

Key result

pH:

6.97

Temp.:

25 °C

DT50:

> 1 yr

Type:

(pseudo-)first order (= half-life)

Remarks on result:

hydrolytically stable based on preliminary test

Key result

pH:

8.77

Temp.:

25 °C

DT50:

> 1 yr

Type:

(pseudo-)first order (= half-life)

Remarks on result:

hydrolytically stable based on preliminary test

Details on results:

On the basis of the pre-test results and in accordance with the guidances no main test has been performed.

Table 1: Hydrolysis at 50 °C, pH = 4

Duration [h]	pH	Temperature [°C]	Concentration [g/L]	Derivation [%] from concentration at 0 h
0	4.88	50.0	1.77	0
1.0		50.0	1.76	-0.4
2.0		50.0	1.56	-11.4
3.0		50.0	1.66	-5.8
46.0		50.0	1.72	-2.6
167.75		49.9	1.69	-4.0
165.75		49.9	1.81	+2.8
171.50	5.00	49.9	1.75	-1.1

At pH 4 the measured concentration after 2 h was 11.4 % lower than the initial concentration. This was however likely to be caused by the deviation of the analytical method and was not a real decrease as can be seen by the concentration values at later times.

Table 2: Hydrolysis at 50 °C, pH = 7

Duration [h]	pH	Temperature [°C]	Concentration [g/L]	Derivation [%] from concentration at 0 h
0	4.88	50.0	1.77	0
1.0		50.0	1.76	-0.4
2.0		50.0	1.56	-11.4
3.0		50.0	1.66	-5.8
46.0		50.0	1.72	-2.6
167.75		49.9	1.69	-4.0
165.75		49.9	1.81	+2.8
171.50	5.00	49.9	1.75	-1.1

Table 3: Hydrolysis at 50 °C, pH = 9

Duration [h]	pH	Temperature [°C]	Concentration [g/L]	Derivation [%] from concentration at 0 h
0	8.95	50.0	1.62	0
1.0		50.0	1.56	-3.7
2.0		50.0	1.64	+1.1
3.0		50.0	1.58	-2.5
46.0		50.0	1.71	+5.9
171.5		49.9	1.68	+3.8
171.75	9.00	49.9	1.71	+5.8

Validity criteria fulfilled:

not applicable

Conclusions:

Guanidine carbonate is hydrolytically stable as evidenced in the pre-test.

Executive summary:

Oberascher (1999) investigated the hydrolytic stability of the test item Guanidine carbonate (CAS 593-85-1) study according to the OECD TG 111 protocol. The GLP-study is considered reliable and conclusive for chemical safety assessment and classification purposes.

The pre-test indicated a half-life at 25 °C of more than one year.

Thus no DT50 was determined and the guanidine kation is considered hydrolytically stable under environmental conditions.

Reference 2

Endpoint:

hydrolysis

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reason / purpose for cross-reference:

read-across source

Preliminary study:

In none of the buffer solutions at pH 4, 7 and 9 at 50 °C more than 10 % of the test substance hydrolysed within 5 days.

Transformation products:

no

Key result

pH:

4.06

Temp.:

25 °C

DT50:

> 1 yr

Type:

(pseudo-)first order (= half-life)

Remarks on result:

hydrolytically stable based on preliminary test

Key result

pH:

6.97

Temp.:

25 °C

DT50:

> 1 yr

Type:

(pseudo-)first order (= half-life)

Remarks on result:

hydrolytically stable based on preliminary test

Key result

pH:

8.77

Temp.:

25 °C

DT50:

> 1 yr

Type:

(pseudo-)first order (= half-life)

Remarks on result:

hydrolytically stable based on preliminary test

Details on results:

On the basis of the pre-test results and in accordance with the guidances no main test has been performed.

Conclusions:

Available data from Guanidine carbonate were used to evaluate the hydrolytic stability of Guanidine hydrochloride.
The hydrolytic stability of Guanidine carbonate (CAS 593-85-1) was invetigated in a study according to the OECD TG 111 protocol.
The GLP-study is considered reliable and conclusive for chemical safety assessment and classification purposes.
The pre-test indicated a half-life at 25 °C of more than one year.
Thus no DT50 was determined and the guanidine kation is considered hydrolytically stable under environmental conditions.

Description of key information

A GLP-Study accoridng to OECD Guideline 111 was Performed with Guanidine carbonate.

According to the the read-across justification only the gunidinium kation is relevant for the hydrolytical properties of guanidine salts.

Therefore the the study performed with Guanidine carbonate was taken as read-across source to fulfill the information requirements for guanidine hydrochloride.

The pre-test indicated a half-life at 25 °C of more than one year.

Thus no DT50 was determined and the guanidine kation is considered hydrolytically stable under environmental conditions.

Key value for chemical safety assessment

Half-life for hydrolysis:

1 yr

at the temperature of:

25 °C