Hexaammonium wolframate

Particle size distribution (Granulometry)

Link to relevant study record(s)

Reference

Endpoint:

particle size distribution (granulometry)

Type of information:

read-across based on grouping of substances (category approach)

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Remarks:

Data from peer-reviewed handbook or collection of data.

Justification for type of information:

1. HYPOTHESIS FOR THE CATEGORY APPROACH: The hypothesis is that properties are likely to be similar or follow a similar pattern because of the presence of a common metal ion, in this case tungstate.
2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES):
Source: Ammonium paratungstate
Target: Ammonium metatungstate
3. CATEGORY APPROACH JUSTIFICATION: See Annex 3 in CSR
4. DATA MATRIX: See Annex 3 in CSR

Reason / purpose for cross-reference:

read-across: supporting information

Principles of method if other than guideline:

Data in this peer-reviewed publication were taken from many sources, including both compilations and primary literature. Where conflicts were found, the value deemed most reliable was chosen for inclusion in the handbook. Reference sources were not provided for this parameter, nor was the experimental method.

GLP compliance:

no

Type of distribution:

counted distribution

Percentile:

D50

Remarks on result:

other: Migrated from fields under 'Mass median diameter' as D50 percentile. No source field for Standard deviation.

Percentile:

other: average crystal size of commercial products

Mean:

> 30 - < 100 µm

St. dev.:

0

The average crystal size of ammonium paratungstate (commercial products) was noted as 30 -100 um. No standard deviation was provided.

Ammonium paratungstate grain size distribution was shown graphically to range from approximately 25 um to 130 um with a peak occurring at approximately 45 um.

Conclusions:

Ammonium paratungstate grain size distribution was shown graphically to range from approximately 25 um to 130 um with a peak occurring at approximately 45 um.

Executive summary:

Due to the similar chemical constituency and structure between the source substance (ammonium paratungstate) and the target substance (ammonium metatungstate), the physico-chemical properties would be expected to be the same or sufficiently similar such that application of read-across is appropriate for this endpoint. For more details, refer to the read-across category approach description in the Category section of this IUCLID submission or Annex 3 of the CSR.

Description of key information

No particle size data are available for ammonium metatungstate (target substance). However, data are available for ammonium paratungstate (source substance), which were used for read-across.

The particle size of ammonium metatungstate (AMT) is estimated based on read-across to ammonium paratungstate (APT). The average crystal size of commercial APT products was noted to be 30-100 um and APT grain size distribution was shown graphically to range from approximately 25 um to 130 um with a peak occurring at approximately 45 um (Lassner and Schubert, 1999). Approximate Average Particle Size (Fisher Sub-Sieve Size): 21-50 um (Osram Sylvania, 2010). Therefore, weight of evidence indicates that the average particle size of APT is in the range of 30-50 um. Based on read-across to APT, the particle size of

ammonium metatungstate is estimated to be near the range of 30-50 um.

Additional information

Due to the similar chemical constituency and structure between the source substance (ammonium paratungstate) and the target substance (ammonium metatungstate), the physico-chemical properties would be expected to be the same or sufficiently similar such that application of read-across is appropriate for this endpoint. For more details, refer to the read-across category approach description in the Category section of this IUCLID submission or Annex 3 of the CSR.