1、Designation:D 1224 92(Reapproved 2001)An American National StandardStandard Test Methods forZinc and Cadmium in Paper1This standard is issued under the fixed designation D 1224;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year
2、 of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon(e)indicates an editorial change since the last revision or reapproval.1.Scope1.1 These test methods cover the determination of cadmiumand zinc either in paper or in highly opaque pigments.1.2The test
3、 methods appear as follows:SectionMethod APolarographic5Method BGravimetric and Volumetric6Method CAtomic Absorption71.3 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 s
4、afety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:C 322 Practice for Sampling Ceramic Whiteware Clays2D 585 Practice for Sampling and Accepting a Single Lot ofPaper,Paperboard,Fiberboard,or Related Products3D 6
5、44 Test Method for Moisture Content of Paper andPaperboard by Oven Drying33.Summary of Test Methods3.1 Three test methods for each element are described:polarographic,either gravimetric or volumetric,and atomicabsorption.The gravimetric procedure is suitable if a po-larograph is not available.For th
6、e determination of zinc in azinc-bearing pigment,the volumetric procedure is recom-mended,because the polarographic procedure is insensitiveover 25%in levels.The polarographic procedure can be usedfor the determination of zinc and cadmium in paper and forcadmium in cadmium-bearing pigments.The prefe
7、rred methodfor each material is based on its concentration and on theavailability of equipment.3.2 When zinc is to be determined volumetrically(cadmiumabsent)one precipitation of heavy metals with washing issufficient.3.3 In the atomic absorption procedure sensitivities for 1%absorption are 0.02 mg/
8、cm3Zn and 0.03 mg/cm3Cd,respec-tively.The repeatability of this method is questionable atpresent for zinc and cadmium concentrations of greater than5%.4.Significance and Use4.1 Zinc is usually present as zinc oxide,zinc sulfide,or aslithopone(a combination of zinc sulfide and barium sulfate),which i
9、s occasionally used in filled paper,paper coatings,andhigh pressure laminates and wallpaper.Some forms of zincoxide have photoelectric properties and are found in certainpapers used for photoreproduction.Zinc or cadmium pigmentsare sometimes added to papers to cause fluorescence,and zincoxide has be
10、en used to enhance the cohesive strength of sometypes of paper coatings.5.Test Method APolarographic5.1 Apparatus:5.1.1 Polarograph,of the manually operated type.Arecord-ing polarograph may be used,although this method is writtenspecifically for a manually operated instrument.5.1.2 Electrolysis Equi
11、pment,including a cell,a droppingmercury electrode,an arrangement for maintaining a constanthead of mercury above the capillary,and a constant-temperature bath.The cell may be of simple design(forexample,a test tube 15 by 85 mm).This cell is fitted with athree-hole notched rubber stopper that will h
12、old the droppingmercury electrode,the contact electrode for the anode(a poolof mercury),and a tube for flushing the solution with nitrogen.5.1.3 Nitrogen Cylinder and Tubing.5.1.4 Other ApparatusPipets,5,15,20,and 50-cm3;volumetric flasks,three 200 cm3.5.2 Reagents:5.2.1 Ammonium ChlorideCrystalline
13、 NH4Cl.5.2.2 Ammonium Hydroxide(NH4OH,14.8 N).5.2.3 Gelatin SolutionDissolve 2 g of gelatin in boilingwater and dilute the clear solution to 1000 cm3.5.2.4 Hydrochloric Acid(HCl,12 N).5.2.5 Nitrogen(with minimum oxygen content).5.2.6 Standard Cadmium Solution(1 cm3=0.0010 g Cd)Dissolve 1.631 g of an
14、hydrous cadmium chloride(CdCl2)in100 cm3of hot water.Cool,dilute to 1000 cm3in a volumetricflask,and mix.1These test methods are under the jurisdiction of ASTM Committee D06 onPaper and Paper Products and are the direct responsibility of Subcommittee D06.92on Test Methods.Current edition approved Se
15、pt.15,1992.Published December 1992.Originallypublished as D 1224 52.Last previous edition D 1224 87(1992)e1.2Annual Book of ASTM Standards,Vol 15.02.3Annual Book of ASTM Standards,Vol 15.09.1Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959,United States.
16、5.2.7 Standard Zinc Solution(1 cm3=0.0010 g Zn)Dissolve 1.245 g of freshly ignited zinc oxide(ZnO)in 50 cm3of hot HCl(1+10).Cool,dilute with water to 1000 cm3in avolumetric flask,and mix.5.3 Sampling and Test Specimen:5.3.1 From each test unit obtained in accordance withMethod D 585(for paper)or Practice C 322(for pigments),prepare a specimen sufficient to contain at least 10 mg of zincor 10 mg of cadmium if present.5.3.2 Normally about 1 g or less of dry paper is sufficient fora single determin