ASTM E1910/E1910M-21

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Designation: E1910/E1910M − 15 E1910/E1910M − 21
Standard Test Method for
Agricultural pH Control Agents, Measurement of pH Change
and Buffering Capacity
This standard is issued under the fixed designation E1910/E1910M; 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 These test methods cover determining if an adjuvant meets the definitions of an acidifier, a basic blend, alkalinity agent, or
buffer in Terminology E1519.
1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each
system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the
two systems may result in non-conformance with the 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.
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
E70 Test Method for pH of Aqueous Solutions With the Glass Electrode
E200 Practice for Preparation, Standardization, and Storage of Standard and Reagent Solutions for Chemical Analysis
E1519 Terminology Relating to Agricultural Tank Mix Adjuvants
3. Summary of Test Method
3.1 Test Method A measures the change in pH of a sample on the addition of an acidifier or a basic blend. alkalinity agent. Test
Method B measures the buffer capacity of the adjuvant by titration.
4. Significance and Use
4.1 This test method is intended for products sold as tank mix adjuvants for use with agricultural products.
These test methods are under the jurisdiction of ASTM Committee E35 on Pesticides, Antimicrobials, and Alternative Control Agentsand are the direct responsibility
of Subcommittee E35.22 on Pesticide Formulations and Delivery Systems.
Current edition approved Oct. 1, 2015April 1, 2021. Published November 2015May 2021. Originally approved in 1997. Last previous edition approved in 20092015 as
E1910/E1910M – 04E1910/E1910M – 15.(2009). DOI: 10.1520/E1910_E191M-15.10.1520/E1910_E191M-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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E1910/E1910M − 21
4.2 Part A provides a determination of whether the pH modification characteristics of the adjuvant tested meet the definition of
an acidifier, alkalinity agent, or a basic blend in Terminology E1519. Part B provides a measure of the buffer capacity of the
adjuvant. This can be used to estimate the amount of a buffer that will be required to keep a spray solution at the desired pH.
4.3 Other pH standards can be used (see Test Method E70) as long as the pHs measured are not outside the range of the standards
used.
4.4 If samples of the material to be used in a particular application are available, the first method can be used to determine what
adjuvant rate is required to obtain the desired pH. The ability of an adjuvant to adjust the pH of a particular system will depend
on the initial pH before addition.
4.5 The second method can be used to determine the amount of an adjuvant required to change the pH of a quantity of spray
solution to the required value (see Note 1).
NOTE 1—Many acidifiers and basic blends also are buffers, so the pH change does not provide a useful measure of buffer capacity.
5. Apparatus
5.1 pH Meter, accurate to 0.01 unit.
5.2 Combination Glass/Calomel Electrode, or separate glass and calomel electrodes or other suitable pH electrode system.
5.3 Beakers, 250 mL.
5.4 Magnetic Stirrer, 120 to 1200 rpm, or equivalent.
5.5 Magnetic Stir Bar, 1 in. (2.5 cm) in length and ⁄8 in. (0.95 cm) in diameter.
5.6 Burette, 50 mL, Class A.
6. Reagents
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 (see Note 2).
NOTE 2—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 12.14 g of anhydrous calcium chloride (CaCl ) and 5.55 g 5.55 g of magnesium
chloride hexahydrate (MgCl ·6H O) to a 1000–mL1000 mL volumetric flask. Dissolve the reagents with approximately 750 mL
2 2
of water and equilibrate to 20°C.20 °C. Dilute the solution to 1000 mL total volume with water at 20°C, stopper the flask and mix
the solution thoroughly. This mixture has a hardness equivalent to 13680 ppm of calcium carbonate (CaCO ) and is based on a
compositional ratio of 4:1 calcium to magnesium.
6.4 Standard Hard Water, equivalent to a total hardness of 342 ppm 342 ppm of calcium carbonate (CaCO ). Transfer 25 mL
Dilute 25 mL of synthetic hard water stock by pipette to a 1000 mL 1000 mL volumetric flask and dilute to 1000 mL volume with
water at 20°C.20 °C. Mix the solution thoroughly (see Note 3).
E1910/E1910M − 21
NOTE 3—It is recommended that the total hardness be checked in accordance with Test Method MT-73, CIPAC 1, EDTA titration. An alternate method
is provided in Test Method D1126, where the value is represented as CaCO . A value within 6 5 % of the nominal hardness value is acceptable.
6.5 pH Reference Solution, pH 4.00.
6.6 pH Reference So
...