1、Designation: E1910/E1910M 15Standard Test Method forAgricultural pH Control Agents, Measurement of pH Changeand Buffering Capacity1This standard is issued under the fixed designation E1910/E1910M; the number immediately following the designation indicates the yearof original adoption or, in the case
2、 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. Scope1.1 These test methods cover determining if an adjuvantmeets the definitions of an acidifier, a
3、basic blend, alkalinityagent, or buffer in Terminology E1519.1.2 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. The values stated ineach system may not be exact equivalents; therefore, eachsystem shall be used independently of the other. Combiningv
4、alues from the two systems may result in non-conformancewith the standard.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine
5、 the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D1126 Test Method for Hardness in WaterD1193 Specification for Reagent WaterE70 Test Method for pH of Aqueous Solutions With theGlass ElectrodeE200 Practice for Preparation, Standardization, and Sto
6、rageof Standard and Reagent Solutions for Chemical AnalysisE1519 Terminology Relating to Agricultural Tank Mix Ad-juvants3. Summary of Test Method3.1 Test Method A measures the change in pH of a sampleon the addition of an acidifier or a basic blend. Test Method Bmeasures the buffer capacity of the
7、adjuvant by titration.4. Significance and Use4.1 This test method is intended for products sold as tankmix adjuvants for use with agricultural products.4.2 Part A provides a determination of whether the pHmodification characteristics of the adjuvant tested meet thedefinition of an acidifier, alkalin
8、ity agent, or a basic blend inTerminology E1519. Part B provides a measure of the buffercapacity of the adjuvant. This can be used to estimate theamount of a buffer that will be required to keep a spray solutionat the desired pH.4.3 Other pH standards can be used (see Test Method E70)as long as the
9、pHs measured are not outside the range of thestandards used.4.4 If samples of the material to be used in a particularapplication are available, the first method can be used todetermine what adjuvant rate is required to obtain the desiredpH. The ability of an adjuvant to adjust the pH of a particular
10、system will depend on the initial pH before addition.4.5 The second method can be used to determine the amountof an adjuvant required to change the pH of a quantity of spraysolution to the required value (see Note 1).NOTE 1Many acidifiers and basic blends also are buffers, so the pHchange does not p
11、rovide a useful measure of buffer capacity.5. Apparatus5.1 pH Meter, accurate to 0.01 unit.5.2 Combination Glass/Calomel Electrode, or separate glassand 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
12、 Bar, 1 in. (2.5 cm) in length and38 in.(0.95 cm) in diameter.5.6 Burette, 50 mL, Class A.6. Reagents6.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended that1These test methods are under the jurisdiction of ASTM Committee E35 onPesticid
13、es, Antimicrobials, and Alternative Control Agentsand are the directresponsibility of Subcommittee E35.22 on Pesticide Formulations and DeliverySystems.Current edition approved Oct. 1, 2015. Published November 2015. Originallyapproved in 1997. Last previous edition approved in 2009 as E1910/E1910M 0
14、4(2009). DOI: 10.1520/E1910_E191M-15.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM Internati
15、onal, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1all reagents shall conform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Societywhere such specifications are available.6.2 Purity of Water Unless otherwise indicated,
16、referenceto water shall be understood to mean reagent water, Type IV, asdefined by Specification D1193 (see Note 2).NOTE 2Type 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 12.1
17、4 g of anhy-drous calcium chloride (CaCl2) and 5.55 g of magnesiumchloride hexahydrate (MgCl26H2O) to a 1000mL volumetricflask. Dissolve the reagents with approximately 750 mL ofwater and equilibrate to 20C. Dilute the solution to 1000 mLtotal volume with water at 20C, stopper the flask and mix thes
18、olution thoroughly. This mixture has a hardness equivalent to13680 ppm of calcium carbonate (CaCO3) and is based on acompositional ratio of 4:1 calcium to magnesium.6.4 Standard Hard Water, equivalent to a total hardness of342 ppm of calcium carbonate (CaCO3). Transfer 25 mL ofsynthetic hard water s
19、tock by pipette to a 1000 mL volumetricflask and dilute to volume with water at 20C. Mix the solutionthoroughly (see Note 3).NOTE 3It is recommended that the total hardness be checked inaccordance with Test Method MT-73, CIPAC 1, EDTA titration.3Analternate method is provided in Test Method D1126, w
20、here the value isrepresented as CaCO3. A value within 6 5 % of the nominal hardnessvalue is acceptable.6.5 pH Reference Solution, pH 4.00.6.6 pH Reference Solution, pH 7.00.6.7 pH Reference Solution, pH 10.00.6.8 0.05 N Sodium Hydroxide, prepared according to Prac-tice E200, or the equivalent.6.9 0.
21、05 N Sulfuric Acid, prepared according to PracticeE200, or the equivalent.6.10 0.05 N Hydrochloric Acid, prepared according toPractice E200, or the equivalent.TEST METHOD AMEASUREMENT OF pHCHANGE OF STANDARD HARD WATER7. Procedure7.1 The pH meter should be turned on and allowed to warmup according t
22、o manufacturers instructions.7.2 Calibrate the pH meter according to manufacturersdirections using the pH 4.00 and pH 7.00 reference standardsfor an acidifier or the pH 7.00 and pH 10.00 referencestandards for a basic blend or alkalinity agent (see Note 4).Place the standards in a 250 mL beaker and
23、stir with themagnetic stirrer and stir bar, while the measurements are beingmade. Care should be taken to thoroughly wash the electrodeswith water between measurements.NOTE 4Other or additional reference standards may be used (see TestMethod E70) as long as the pHs measured are not outside the range
24、 of thestandards used.7.3 Place a clean stir bar and 100 mL of standard hard water(see Note 5) in a 250 mL beaker. Begin stirring with themagnetic stirrer. After carefully rinsing the electrodes, placethem in the water and measure and record the pH, whichshould be between 5.5 and 7.NOTE 5Other water
25、 samples can be used if appropriate. In this casethe initial pH may not be between 5.5 and 7. For specific applications theactual water to be used is preferred.7.4 Add 2 mL of the adjuvant to be tested to the beaker andallow to stir for 5 min. Other dilutions may be used if specifiedon the product l
26、abel.7.5 Record the new pH value.7.6 Remove the electrodes from the solution, clean them,and store them properly. Dispose of the solution properly.8. Report8.1 Report the initial and final pH values (see Note 6).NOTE 6For an acidifier the final pH should be lower than the initial.For a basic blend o
27、r alkalinity agent it should be higher.9. Precision and Bias9.1 The precision and bias of this test method has not beendetermined.TEST METHOD BBUFFER CAPACITY10. Procedure10.1 Turn on and warm up the pH meter according tomanufacturers directions.10.2 Calibrate the pH meter according to manufacturers
28、directions using the pH 4.00 and pH 7.00 reference standardsfor an acidifier or acidic buffer, or the pH 4.00 and pH 10.00reference standards for a basic blend, alkaline buffer, oralkalinity agent (see Note 7). The standards should be placed ina 250 mL beaker and stirred with the magnetic stirrer an
29、d stirbar, while the measurements are being made. Care should betaken to thoroughly wash the electrodes with water betweenmeasurements.NOTE 7Other or additional reference standards may be used (see TestMethod E70) as long as the pHs measured are not outside the range of thestandards used.10.3 Place
30、a clean stir bar and 100 mL of standard hardwater (see Note 8) in a 250 mL beaker. Begin stirring with themagnetic stirrer. After carefully rinsing the electrodes, placethem in the water and measure and record the pH, whichshould be between 5.5 and 7.NOTE 8Other water samples can be used if appropri
31、ate. In this casethe initial pH may not be between 5.5 and 7. For specific applications theactual water to be used is preferred.10.4 For an acidifier or acidic buffer fill the burette with0.05 N sodium hydroxide. For a basic blend, alkaline buffer, oralkalinity agent, fill the burette with 0.05 N hy
32、drochloric acidor 0.05 N sulfuric acid. Record the initial volume.3“Analysis of Technical and Formulated Pesticides,” CIPAC Handbook, Vol 1,compiled by Ashworth, R de B., Henriet, J., Lovett, J.F., Collaborative InternationalPesticide Analytical Council Ltd., Great Britain, 1970.E1910/E1910M 15210.5
33、 Weigh 2 6 0.1 g to the nearest 0.01 g of the adjuvantto be tested (see Note 9) into the beaker and allow to stir for 5min.NOTE 9If necessary for a particular product, the sample size should beadjusted to give a titration volume between 5 and 40 mLs.10.6 Record the pH versus volume titration curve.
34、Thecurve should be measured carefully in the region of the initialwater pH.10.7 From the titration curve determine the volume oftitratant required to return the sample pH to its initial value.11. Calculation11.1 Calculate the number of milliequivalents of acid (for anacidifier or acidic buffer) or b
35、ase (for a basic blend, alkalinebuffer, or alkalinity agent) per gram of product. Multiply thetitration volume times the concentration of the titratant solu-tion. Divide this result by the product weight.meq of acid or baseGramofA5T 0.05 meq/mL!S(1)where:meq = MilliequivalentsA = AdjuvantS = Sample
36、Weight (g)T = Titration Volume (mL)12. Report12.1 Report the number of milliequivalents of acid (for anacidifier or acidic buffer) or base (for a basic blend, alkalinebuffer, or alkalinity agent) per gram of adjuvant.13. Precision and Bias13.1 The precision and bias of this test method has not beend
37、etermined.14. Keywords14.1 acidifier; adjuvant; agricultural adjuvant; alkalinityagent; basic blend; buffer; pHASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advise
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