Sodium phosphinate

Additional physico-chemical information

Administrative data

Endpoint:

other: crystallisation point

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

Test material

Test material information

Constituent 1

Reference substance name:

Sodium phosphinate

EC Number:

231-669-9

EC Name:

Sodium phosphinate

Cas Number:

7681-53-0

Molecular formula:

H3O2P.Na

IUPAC Name:

sodium phosphinate

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