ASTM E1945-21

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Designation: E1945 − 02 (Reapproved 2016) E1945 − 21
Standard Test Method for
Percent Dispersibility
This standard is issued under the fixed designation E1945; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This test method is used to determine the percent dispersibility of dry pesticide formulations.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use. For specific precautionary statements see Section 7.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
D1126 Test Method for Hardness in Water
D1193 Specification for Reagent Water
3. Summary of Test Method
3.1 A known amount of dry pesticide formulation is added to a 250-mL250 mL mixing cylinder that has been filled to volume with
standard water. The mixing cylinder is then stoppered and inverted 30 times in 2 min. The mixing cylinder is allowed to stand for
1 min. After 1 min, the top 225 mL is drawn off and the remaining suspension is dried. The residue weight will determine percent
dispersibility.
4. Significance and Use
4.1 This test method is designed specifically for dry formulations.
4.2 This test method may not be applicable to all dry formulations such as those containing either liquid technicalswater soluble
or liquid technicals/pesticides or ingredients that rise to the top upon separation.
This test method is under the jurisdiction of ASTM Committee E35 on Pesticides, Antimicrobials, and Alternative Control Agents and is direct responsibility of
Subcommittee E35.22 on Pesticide Formulations and Delivery Systems
Current edition approved Nov. 1, 2016Oct. 1, 2021. Published November 2016November 2021. Originally approved in 1998. Last previous edition approved in 20082016
as E1945 – 02(2008).(2016). DOI: 10.1520/E1945-02R16.10.1520/E1945-21.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
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E1945 − 21
4.3 This test method may not be applicable to those technicals that decompose below the drying temperature.
4.4 This test method should be run in duplicate.
4.5 Products containing water soluble or volatile components may result in errors.
5. Apparatus
5.1 Balance, top loading, with an accuracy of 60.01 g or better.
5.2 Gravity Oven.
5.3 Weighing Dish, 150 mL capacity or greater.
5.4 Vacuum Apparatus, see Fig. 1, equipped with a vented stopper.
5.5 Mixing Cylinder, stoppered, 250-mL,250 mL, flat bottom.
5.6 Timer, adjustable, with an accuracy of 61 s.
5.7 Weighing Dish, aluminum (57 × 18 mm) or petri dish or equivalent.
FIG. 1 Vacuum Apparatus
E1945 − 21
5.8 Filtering Flask, heavy wall, 500 mL.
6. Reagents (Test Water)
6.1 Purity of Reagents—Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all
reagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society where
such specifications are available.
6.2 Purity of Water—Unless otherwise indicated, reference to water shall be understood to mean reagent water, Type IV, as defined
by Specification D1193.
NOTE 1—Type IV grade reagent water may be prepared by distillation, ion exchange, reverse osmosis, electrodialysis, or a combination thereof.
6.3 Synthetic Hard Water Stock, transfer 12.14 g of anhydrous calcium chloride (CaCl ) and 5.55 g of magnesium chloride
hexahydrate (MgCl •6H O) to a 1000-mL1000 mL volumetric flask. Dissolve the reagents with approximately 750 mL of water
2 2
and equilibrate to 20°C.20 °C. Dilute the solution to 1000 mL total volume with water at 20°C,20 °C, stopper the flask, and mix
the solution thoroughly. This mixture is equivalent to 13 680 ppm as calcium carbonate (CaCO ) and is based on a compositional
ratio of 4:1 calcium carbonate to magnesium carbonate.
6.3.1 Soft Water, equivalent to a total hardness of 34.2 ppm as calcium carbonate (CaCO ). Transfer 2.50 mL of synthetic hard
water stock by pipet to a 1000-mL volumetric flask and dilute to volume 1000 mL volumetric flask. Dilute to the 1000 mL mark
with water at 20°C.20 °C. Mix solution thoroughly.
NOTE 2—It is recommended that total hardness be checked in accordance with Test Method MT-73, CIPAC 1, EDTA titration. An alternate method is
provided in Test MethodsMethod D1126 where the value is represented as CaCO . A value within 65 % of the nominal hardness value is acceptable.
6.3.2 Hard Water, equivalent to a total hardness of 342 ppm as calcium carbonate (CaCO ). Transfer 25.0 mL of synthetic hard
water stock by
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