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Physical & Chemical properties

Water solubility

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Endpoint:
water solubility
Type of information:
experimental study
Adequacy of study:
key study
Study period:
July 2011
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study without detailed documentation
Qualifier:
according to
Guideline:
OECD Guideline 105 (Water Solubility)
Deviations:
yes
Remarks:
: pH value at which the measurements were conducted is not reported
Principles of method if other than guideline:
The water solubility von Creatine monohydrate and creatine (water-free) were compared with each other.
GLP compliance:
no
Other quality assurance:
ISO/IEC 17025 (General requirements for the competence of testing and calibration laboratories)
Type of method:
flask method
Key result
Water solubility:
15.8 g/L
Conc. based on:
test mat.
Incubation duration:
24 h
Temp.:
20 °C
Remarks on result:
other: Water solubility of Creatine monohydrate. No information available at which pH the measurement was conducted
Key result
Water solubility:
15.1 g/L
Conc. based on:
test mat.
Incubation duration:
48 h
Temp.:
20 °C
Remarks on result:
other: Water solubility of Creatine. No information available at which pH the measurement was conducted
Details on results:
After 24 h the creatine concentration does not change anymore in the Creatine monohydrate sample. The water solubility is reported as the mean of the 24 h, 48 h and 72 h value.
In the sample of water free creatine the creatine concentration does not change after 48 h anymore. The water solubility is reported as the mean of the 48 h and 72 h value.

Table 1: Creatine and Creatinine concentration

Stirring time

Analyte

Sample A (Creatine Monohydrate)

Sample B (water-free Creatine)

 

 

Concentration [g/L]

Concentration [g/L]

1 h

Creatine

14.163

13.692

 

Creatinine

2.63

12.3

24 h

Creatine

15.951

14.177

 

Creatinine

29.4

36.3

48 h

Creatine

15.527

14.912

 

Creatinine

57.4

59.2

72 h

Creatine

15.911

15.325

 

Creatinine

87.0

85.3

Besides the water solubility the rate of dissolving and the dissolution heat of creatine and creatine monohydrate was measured and compared with each other.

Rate of dissolution:

Creatine monohydrate: 12 min 41 s

Creatine (water free): 14 min, 59 s

Table 2: Dissolution heat

Time of stirring

Sample A (Creatine monohydrate)

Sample B (Creatine water-free)

0

20

20

1

20

20.5

2

21

21

3

21

21.5

4

21.5

21.5

5

21.5

22

10

21.5

22.5

15

22

23

30

22.5

23.5

45

23.5

24

60

24

24.5

Conclusions:
Based on the result of this study the water solubility of creatine and creatine monohydrate is comparable with each other. Both are very soluble (> 10000 mg/l) in water.
Executive summary:

The water solublility of Creatine and Creatine Monohydrate was determined according the OECD guideline 105. The solubility of Creatine Monohydrate in water is 15.8 g/l and 15.1 g/L for Creatine (water-free), respectively. Therefore both are very soluble (>10000 mg/l).

Besides that the rate of dissolution and dissolution heat were determined. These parameter were also comparable for Creatine and Creatine Monohydrate.

Rate of dissolution:

Creatine monohydrate: 12 min 41 s

Creatine (water free): 14 min, 59 s

Dissolution heat (see Table 2): exothermic dissolution.

Endpoint:
water solubility
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
data from handbook or collection of data
Remarks:
Value is published in Hazardous Substance Data Bank (HSDB). However, the temperature that is related to the value of the water solubility is not reported.
Qualifier:
equivalent or similar to
Guideline:
other: no guiedeline reported
Principles of method if other than guideline:
Information on the exact test method is not available. The water solubility of creatine (peer-reviewed value) from the "Handbook of aqueous solubility data" is cited in the Hazardous Substances Data Bank (HSDB).
GLP compliance:
not specified
Type of method:
other: no method reported
Water solubility:
13.3 g/L
Conc. based on:
test mat.
Remarks on result:
other: Temperature that relates to the value of the water solubility is not reported.
Details on results:
No details available (> citation in HSDB).
Conclusions:
The water solubility of creatine is reported to be 13,3 g/L.
Executive summary:

The water solubility of creatine as reported in the "Handbook of aqueous solubility" and cited in the Hazardous Substances Data Bank (HSDB) is 13,3 g/L.

Description of key information

Information for creatine is available from the "Handbook of aqueous solubility data"

(as cited in the Hazardous Substances Data Base). The 2003 Safety Data Sheet form Degussa cites a value for creatine monohydrate, from which a value for the analogue creatine can be calculated. Furthermore the water solubility of creatine and creatine monohydrate were determined in a study according the OECD guideline 105 (Stroot, 2011). It is reported to be 15.1 g/L for Creatine and 15.8 g/L for Creatine monohydrate.

Key value for chemical safety assessment

Water solubility:
15.1 g/L
at the temperature of:
20 °C

Additional information

The water solubility of creatine as reported in the "Handbook of aqueous solubility" and cited in the Hazardous Substances Data Bank (HSDB) is 13.3 g/L. However, the temperature that is related to the value of the water solubility is not reported.

The water solubility of creapure (creatine monohydrate) of 14 g/L is reported in the Degussa Safety Data Sheet (SDS) from 2003. In a read-across approach the water solubility of creatine was calculated based on the value for creatine monohydrate. The calculated water solubility of creatine is approx. 12.3 g/L.

Besides that the water solubility of Creatine and Creatine monohydrate was determined in a study according the OECD guideline 105 (Stroot, 2011). It is reported to be 15.1 g/L for Creatine and 15.8 g/L for Creatine monohydrate.

Creatine is manufactured by drying of creatine monohydrate. The only difference between creatine and creatine monohydrate is the water content of the substances. Creatine (C4H9N3O2) does not contain water molecules, whereas creatine monohydrate contains one water molecule per substance molecule (C4H9N3O2 x H2O). When dissolved in water, there is no chemical difference between creatine monohydrate and creatine. Therefore, the approach of calculating the water solubility of creatine from the water solubility of creatine monohydrate is considered to be valid.

The results of both sources are scientifically in line. As both values are above 10000 mg/l water, creatine can be classified as very soluble.