Orthophosphoric acid

Particle size distribution (Granulometry)

Administrative data

Endpoint:

particle size distribution (granulometry)

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

13 July 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Justification for type of information:

Study only concerns one registrant

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2017

Report date:

2017

Materials and methods

GLP compliance:

yes (incl. QA statement)

Remarks:

Date of Inspection: 13 to 15 October 2015 Date of Signature on Certificate: 13 January 2016

Other quality assurance:

other: ISO 13320:2009; CIPAC MT 187

Type of method:

Laser scattering/diffraction

Type of distribution:

volumetric distribution

Test material

Test material information

Constituent 1

Reference substance name:

Orthophosphoric acid

EC Number:

231-633-2

EC Name:

Orthophosphoric acid

Cas Number:

7664-38-2

Molecular formula:

H3O4P

IUPAC Name:

phosphoric acid

Details on test material:

- Name of test material (as cited in study report): phosphoric acid
- Molecular formula (if other than submission substance): not applicable
- Molecular weight (if other than submission substance): not applicable
- Smiles notation (if other than submission substance): not applicable
- InChl (if other than submission substance): not applicable
- Structural formula attached as image file (if other than submission substance): not applicable
- Substance type: no data
- Physical state: no data
- Analytical purity: no data
- Impurities (identity and concentrations): no data
- Composition of test material, percentage of components: no data
- Isomers composition: not applicable
- Purity test date: no data
- Lot/batch No.: no data
- Expiration date of the lot/batch: no data
- Radiochemical purity (if radiolabelling): not applicable
- Specific activity (if radiolabelling): not applicable
- Locations of the label (if radiolabelling): not applicable
- Expiration date of radiochemical substance (if radiolabelling): not applicable
- Stability under test conditions: no data
- Storage condition of test material: no data
- Other: no data

Results and discussion

Particle size

Particle size 1

Percentile:

D10

Mean:

15.639 µm

St. dev.:

0.066

Particle size 2

Percentile:

D50

Mean:

30.449 µm

St. dev.:

0.168

Particle size 3

Percentile:

D90

Mean:

187.036 µm

St. dev.:

3.841

Any other information on results incl. tables

Standard visual observation

Sample observed to be a polydispersed , colourless crystalline solid with lumps and clusters.

Observation using 3.2 objective lens

The particles appeared to be irregular shaped crystals. The smallest individual particle size was approximately 6.4 μm and the largest individual size was approximately 144.0 μm.

Observation using 40 objective lens

The sample was observed to be made up of single crystalline particles with some agglomerations present.

Laser Diffraction Particle Size Analysis

Date : 26/07/2017

Operator : G. Jordan

Preparation : Sample tested as received

SOP Reference : CTL SOP No. 417

During the method development phase of the analysis trials were conducted using the small volume (wet) module (SVM) due to the sample being hygroscopic. The results of these trials indicated that the most appropriate test and material parameters to obtain the optimum measurements were:

Module : SVM

Dispersant : Silicone Oil

Dispersion speed : 2300 rpm

Refractive index (sample) : 0.000 n

Absorption : 5e-005 AU

Analysis Model : General Purpose (Normal)

Using the identified parameters, the particle size was analysed over the range 0.02 μm to 2000 μm. The results of the formal analysis are presented in Table 9:1. In addition, a graph of volume (%) versus Particle Diameter (μm), and full particle size distribution, is provided in Graph 9.A (Average of 5 runs).

The table of results can be found below:

Table 9.1: Full Test Results

	RUN 1	RUN 2	RUN 3	RUN 4	RUN 5	Average*
Volume weighted mean	58.301	59.314	60.064	61.088	62.191	60.192
Median	30.240	30.328	30.419	30.557	30.714	30.449
Mode	27.109	29.946	26.844	26.795	26.672	26.873
d10 – 10% of material is <	15.558	15.584	15.624	15.708	15.723	15.639
d50 – 50% of material is <	30.240	30.328	30.419	30.557	30.714	30.449
d90 – 90% of material is <	181.508	184.538	189.611	189.611	192.504	187.036

All results are in µm

*Average result is calculated from the entirety of data captured in each run and is not a simple arithmetic mean.

0.69% by volume of sample was seen to be < 10.00 µm

 

Table 9.2: Standard Deviation results

Run No	1	2	3	4	5	STDVP	%STDVP
d10 – 10% of material is <	15.558	15.584	15.624	15.708	15.723	0.066	0.4
d50 – 50% of material is <	30.240	30.328	30.419	30.557	30.714	0.168	0.6
d90 – 90% of material is <	181.508	184.538	189.611	189.611	192.504	3.841	2.1
d15.78 – 15.78% of material is <	17.764	17.874	17.821	17.900	17.919	0.062	0.3
GSD	1.702	1.705	1.707	1.707	1.714	0.004	0.2

GSD = Geometric standard deviation of the lognormal particle size distribution (calculated from d50/d15.78)

STDVP = standard deviation of the population

% STDVP = percentage standard deviation of the population

 

Coefficient of variation for d50 is less than 3%; d10 and d90 are less than 5%. Thus repeatability of

the characteristic particles in the size distribution are within the acceptable limits as per the ISO

13320-1 test standard.

Applicant's summary and conclusion

Conclusions:

The average particle sizes were as follows:
d10 - 15.639 μm
d50 - 30.449 μm
d90 - 187.036 μm

Executive summary:

Laser diffraction was used to determine the particle size distribution of phosphoric acid. The sample is initially observed to determine whether sieving of the material is required. A method development for the particle size analysis on the material is then undertaken

to obtain the correct parameters for the formal analysis. The method development is employed to identify the most appropriate optical properties for the material, the correct dispersant, dispersion pressures and sample compatibility. Once these parameters are obtained the final

sample is then analysed using the Malvern Mastersizer 2000 Laser Diffraction Analyser. 5 runs are completed to ensure repeatability of results. The test is conducted in accordance with ISO 13320:2009 and CIPAC MT 187.

Due to the powder being hygroscopic, the analysis was carried out using the ‘wet’, small volume dispersion system.

The results of the laser diffraction test conducted to determine the particle size of Phosphoric Acid 99% Crystalized are summarised in the table below. The analysis was conducted using the small volume (wet) module (SVM) with silicone oil as the dispersant.

Particle Size Analysis using small volume (wet) module (SVM).	Average*
Volume weighted mean	60.192
Median	30.449
Mode	26.873
d10 – 10% of material is <	15.639
d50 – 50% of material is <	30.449
d90 – 90% of material is <	187.036
volume of sample <10.00 µm	0.69%