N-glycylglycine

Water solubility

Administrative data

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

None

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Remarks:

Although the study has not been performed in accordance with any guideline, its results are very comparable with other literary sources

Data source

Reference

Reference Type:

publication

Title:

Densities and solubilities of glycylglycine and glycyl-l-alanine in aqueous electrolyte solutions

Author:

Breil MP, Mollerup JM, Rudolph ESJ, Ottens M, van der Wielen LAM

Year:

2004

Bibliographic source:

Fluid Phase Equilibria 215: 221–225

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

Glycylglycine was added in abundance to ensure saturation, followed by a defined time of stirring in a thermostated water bath and subsequent filtration to separate excess test material.

GLP compliance:

no

Type of method:

flask method

Test material

Test material information

Constituent 1

Reference substance name:

N-glycylglycine

EC Number:

209-127-8

EC Name:

N-glycylglycine

Cas Number:

556-50-3

Molecular formula:

C4H8N2O3

IUPAC Name:

N-glycylglycine

Test material form:

solid

Details on test material:

Purchased from Bachem A.G. (Bubendorf, Switzerland)

Results and discussion

Water solubility

Key result

Water solubility:

1.74 other: mol/kg water

Conc. based on:

test mat. (dissolved fraction)

Incubation duration:

>= 18 - <= 24 h

Temp.:

298.15 K

pH:

5.65

Remarks on result:

other: The pH was calculated based on theoretical considerations.

Details on results:

The densitiy of this saturated glycylglycine-water solution indicated as key result was determined to be 1.0776 g cm-3.

Any other information on results incl. tables

Solubility and density of saturated glycylglycine solutions in the presence of different NaCl concentrations:

NaCl (mol/kg H2O)	density(sat.sol.) (g/cm3)	Solubility (mol/kg H2O)
0.1003	1.0807	1.73
	1.0825	1.76
0.2012	1.0841	1.74
	1.0869	1.80
0.4041	1.0856	1.80
	1.0943	1.83
0.5071	1.0984	1.85
	1.0985	1.84
0.6082	1.1024	1.87
	1.1021	1.85
0.8151	1.1098	1.87
	1.1095	1.89
0.9182	1.1130	1.88
	1.1129	1.88
1.0217	1.1163	2.10
	1.1162	1.89
2.0436		1.98
3.0061		1.97
3.9870		2.01
4.9859		2.07
5.5928		2.10
5.6093		2.12
5.6202		2.08
5.6300		2.10
6.0279 (saturation)		2.12
6.0503 (saturation)		2.16

Solubility and density of saturated glycylglycine solutions in the presence of different Na2SO4 concentrations:

Na2SO4 (mol/kg H2O)	density(sat.sol.) (g/cm3)	Solubility (mol/kg H2O)
0.1003	1.0920	1.84
	1.0914	1.82
0.1735	1.1042	1.89
	1.1042	1.85
0.2012	1.1213	1.91
	1.1201	1.88
0.3524	1.1005	2.01
	1.0996	1.94
0.5054	1.1376	2.11
	1.1376	1.97
0.6078	1.1478	2.09
	1.1469	2.00
0.8146	1.1669	2.03
	1.1665	2.00
1.0241	1.1860	2.07
	1.1850	2.03

Solubility and density of saturated glycylglycine solutions in the presence of different (NH4)2SO4 concentrations:

(NH4)2SO4 (mol/kg H2O)	density(sat.sol.) (g/cm3)	Solubility (mol/kg H2O)
0.1012	1.0878	1.82
	1.0868	1.81
0.2028	1.0958	1.89
	1.0951	1.87
0.4095	1.1102	2.00
	1.1093	1.98
0.5150	1.1169	2.05
	1.1155	2.01
0.6217	1.1237	2.07
	1.1223	2.05
0.8411	1.1344	2.12
	1.1331	2.07
0.9524	1.1401	2.12
	1.1389	2.08
1.0652	1.1452	2.14
	1.1439	2.10

Applicant's summary and conclusion

Conclusions:

In this study, the water solubility of glycylglycine was determined to be 1.74 mol/kg water at 298.15 K and pH 5.65. In the presence of increasing salt concentrations of NaCl, Na2SO4 and (NH4)2SO4, the solubility of glycylglycine increases moderately.

Executive summary:

Breil et al. (2004) determined the water solubility of glycylglycine in pure water as well as in aqueous electrolyte solutions at various salt concentrations of NaCl, Na2SO4 and (NH4)2SO4.

To this end, glycylglycine was added in abundance to the solutions consisting either of pure water or different salt concentrations dissolved in water to ensure saturation. These solutions were subsequently stirred for 18 to 24 hours at 298.15 K . After equilibration, samples were taken and filtered to separate excess test item. The concentration of test item was subsequently determined by spectrophotometry.

The water solubility of glycylglycine was determined to be 1.74 mol/kg water at 298.15 K and pH 5.65. In the presence of increasing salt concentrations of NaCl, Na2SO4 and (NH4)2SO4, the solubility of glycylglycine increases moderately.