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Physical & Chemical properties

Additional physico-chemical information

Administrative data

Endpoint:
additional physico-chemical information
Type of information:
experimental study
Adequacy of study:
other information
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Study meets generally accepted scientific principles

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1998
Report Date:
1998

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
In a cryostatic bath, a reactor is stirred and the temperature is measured with a probe. The temperatures are recorded continously on a tracing table.
GLP compliance:
not specified
Endpoint investigated:
other: crystallisation point

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material: liquid sample, hyposphosphite de sodium 810 g/L
- Lot/batch No.: 4 samples have been tested at different concentrations in the same conditions
- concentrations tested between 810 g/L and 850 g/L
commercial concentration is at 810 g/L and correspond to an oversaturated solution. But this solution seems to be stable at 20°C
For details see table 1 in Results freetext.

Results and discussion

Results:
Without spiking, at a concentration of 810 g/L a mass crystallisation is observed, followed by a rapid increase in temperature. Redissolution is low.
At higher concentrations crystallisation start slowly without mass crystallisation nor increase in temperature.
Spiking does not accelerate significantively the crystallisation.

Any other information on results incl. tables

Table 1: summary of the measured crystallisation points for the the 4 samples tested

Name

Sample designation

Number of lot

Concentration (g/L)

Crystallisation point (°C)

Sodium hypophosphite

L1

97-51

810

-25

H3PO2

L11

nd

50%

-27 *;

Sodium hypophosphite

L12

nd

855

17 *; 19 **

Sodium hypophosphite

L13

nd

820

-5 *; -1 **

* without spiking

** with spiking

nd: no data

Applicant's summary and conclusion

Conclusions:
In the test conditions, the crystallisation of saturated solutions of sodium hypophosphite is very low and occur at: -25°C at 810 g/L (commercial concentration). Only one particularity is observed at this concentration: the phenomenon occurs in mass and is followed with a rapid increase in temperature. However at the same concentration the solution is stable at 20°C.
Spiking does not accelerate crystallisation.
Executive summary:

The crystallisation point of saturated solutions of sodium hypophosphite was measured under stirring in a cryostatic bath at 4 concentrations.

Without spiking, at a concentration of 810 g/L a mass crystallisation is observed at -25°C, followed by a rapid increase in temperature. Redissolution is low. At higher concentrations (820 g/L and 850 g/L) crystallisation start slowly and occurs at -5°C and 17°C respectively. No mass crystallisation nor increase in temperature was observed in those cases.

Spiking does not accelerate significatively the crystallisation.

As the study meets generally scientific principles the study is considered as reliable with restrictions