Chlorothalonil

Particle size distribution (Granulometry)

Link to relevant study record(s)

Reference

Endpoint:

particle size distribution (granulometry)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

31 Jan 1996

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

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

Qualifier:

no guideline followed

Principles of method if other than guideline:

METHOD
- Samples of test substance, 2787-012348 (wet milled) and Bravo 720 were applied to aluminum stubs.
- The samples were applied with an airbrush at 3 different rates: 1250 ppm, 2500 ppm and 5000 ppm active ingredient.
- The samples were coated with gold to improve conductivity.
- They were examined in the JEOL 35CX scanning electron microscope.

GLP compliance:

no

Type of method:

microscopic examination

Remarks:

scanning electron microscope

Type of particle tested:

agglomerate

Type of distribution:

volumetric distribution

Remarks on result:

other: see 'Any other information on results incl. tables'

Key result

Percentile:

other: average

Mean:

>= 2 - <= 10 µm

Remarks on result:

other: see 'Any other information on results incl. tables'

Remarks:

The small particles were easily dislodged in the microscope column disrupting the image.

Size:

>= 1 - <= 30 µm

Remarks on result:

other: The small particles were easily dislodged in the microscope column disrupting the image.

The wet milled 2787-(012348) has a very small particle size with an average about 1 µm. Many of these particles appear to agglomerate, forming larger clusters 2 - 10 µm in diameter. The significantly small particle size and the increased surface area of the clusters (2787-012348) may be important. The particles of the wet milled test substance were difficult to photograph. The small particles were easily dislodged in the microscope column disrupting the image.

Table 1 Overview

Sample	Size Range (µm)	Average (µm)	Shape
Test substance	1 - 30	2 - 10	irregular
Bravo 720	0.5 - 6	0.5 - 3	rectangular
2787 -012348 (Wet milled)	0.4 - 5	0.5 - 1	irregular

Conclusions:

The particles of the wet milled test substance were difficult to photograph, were irregularlly shaped with a size of 2 - 10 µm on average.

Executive summary:

The particle size distribution of test substance was determined by SEM. The particles of the wet milled test substance were irregularly shaped with an avarage size of 2 - 10 µm and were easily dislodged in the microscope column disrupting the image.

Description of key information

Particles were irregularly shaped with an avarage size of 2 - 10 pm, particle size analysis SEM, Krutyholowa 1996.