Designation:D1209–05
Standard Test Method for
Color of Clear Liquids(Platinum-Cobalt Scale)1
This standard is issued under thefixed designation D1209;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(e)indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
1.Scope*
1.1This test method describes a procedure for the visual measurement of the color of essentially light colored liquids (Note1).It is applicable only to materials in which the color-producing bodies present have light absorption charac-teristics nearly identical with those of the platinum-cobalt color standards used.
N OTE1—A procedure for estimating color of darker liquids,described for soluble nitrocellulose base solutions,is given in Guide D365.
1.2The values stated in SI units are to be regarded as standard.No other units of measurement are included in this standard.
1.3For purposes of determining conformance of an ob-served or a calculated value using this test method to relevant specifications,test result(s)shall be rounded off“to the nearest unit”in the last right-hand digit used in expressing the specification limit,in accordance with the rounding-off method of Practice E29.
1.4This 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 appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.For specific hazard statements see Section6.
1.5For specific hazard information,see the Material Safety Data Sheet.
2.Referenced Documents
2.1ASTM Standards:2
D156Test Method for Saybolt Color of Petroleum Prod-ucts(Saybolt Chromometer Method)
D365Guide for Soluble Nitrocellulose Base Solutions
D1193Specification for Reagent Water
E29Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications
E202Test Methods for Analysis of Ethylene Glycols and Propylene Glycols
E346Test Methods for Analysis of Methanol
3.Significance and Use
3.1The property of color of a solvent varies in importance with the application for which it is intended,the amount of color that can be tolerated being dependent on the color characteristics of the material in which it is used.The paint, varnish,and lacquer solvents,or diluents commercially avail-able on today’s market normally have little or no color.The presence or absence of color in such material is an indication of the degree of refinement to which the solvent has been subjected or of the cleanliness of the shipping or storage container in which it is handled,or both.
3.2For a number of years the term“water-white”was considered sufficient as a measurement of solvent color. Several expressions for defining“water-white”gradually ap-peared and it became evident that a more precise color standard was needed.This was accomplished in1952with the adoption of Test Method D1209using the platinum-cobalt scale.This test method is similar to the description given in Standard Methods for the Examination of Water and Waste Water3and is referred to by many as“APHA Color.”The preparation of these platinum-cobalt color standards was originally described by A. Hazen in the American Chemical Journal4in which he assigned the number5(parts per ten thousand)to his platinum-cobalt stock solution.Subsequently,in theirfirst edition(1905) of Standard Methods for the Examination of Water,the American Public Health Association,using exactly the same
concentration of reagents,assigned the color designation500 (parts per million)which is the same ratio.The parts per million nomenclature is not used since color is not referred directly to a weight relationship.It is therefore recommended that the incorrect term“Hazen Color”should not be used.Also, because it refers primarily to water,the term“APHA Color”is
1This test method is under the jurisdiction of ASTM Committee D01on Paint and Related Coatings,Materials,and Applications and is the direct responsibility of Subcommittee D01.35on Solvents,Plasticizers,and Chemical Intermediates.
Current edition approved May15,2005.Published May2005.Originally approved in1952.Last previous edition approved in2000as D1209–00.
2For referenced ASTM standards,visit the ASTM website,,or contact ASTM Customer Service at For Annual Book of ASTM Standards volume information,refer to the standard’s Document Summary page on the ASTM website.
3Standard Methods for the Examination of Water and Waste Water,M.Franson, Ed.,American Public Health Assoc.,14th ed.,1975,p.65.
4Hazen,A.,“New Color Standard for Natural Waters,”American Chemical Journal,V ol XIV,1892,p.300–310.
*A Summary of Changes section appears at the end of this standard. Copyright©ASTM International,100Barr Harbor Drive,PO Box C700,West Conshohocken,PA19428-2959,United States.
undesirable.The recommended nomenclature for referring to the color of organic liquids is “Platinum-Cobalt Color,Test Method D 1209.”
3.3The petroleum industry uses the Saybolt colorimeter Test Method D 156for measuring and defining the color of hydrocarbon solvents;however,this system of color measure-ment is not commonly employed outside of the petroleum industry.It has been reported by various sources that a Saybolt color of +25is equivalent to 25in the platinum-cobalt system or to colors produced by masses of potassium dichromate ranging between
4.8and
5.6mg dissolved in 1L of distilled water.Because of the differences in the spectral characteristics of the several color systems being compared and the subjective manner in which the measurements are made,exact equivalen-cies are difficult to obtain.
4.Apparatus
4.1Spectrophotometer ,equipped for liquid samples and for measurements in the visible region.
N OTE 2—The spectrophotometer used must be clean and in first-class operating condition.The instrument should be calibrated in accordance with the instructions given in the Standards for Checking the Calibration of Spectrophotometers (200to 1000nm).5
4.2Spectrophotometer Cells ,matched having a 10-mm light path.
4.3Color Comparison Tubes —Matched 100-mL,tall-form Nessler tubes,provided with ground-on,optically clear,glass caps.Tubes should be selected so that the height of the 100-mL graduation mark is 275to 295mm above the bottom of the tube.
4.4Color Comparator —A color comparator constructed to permit visual comparison of light transmitted through tall-form,100-mL Nessler tubes in the direction of their longitu-dinal axes.The comparator should be constructed so that white light is passed through or reflected off a white glass plate and directed with equal intensity through the tubes,and should be shielded so that no light enters the tubes from the side.6
5.Reagents
5.1Purity 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 Commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are available.7Other grades may be used,provided it is first ascertained that the reagent is of sufficiently high purity to permit its use without lessening the accuracy of the determination.
5.2Purity of Water —Unless otherwise indicated,references to water shall be understood to mean reagent water conforming to Type IV of Specification D 1193.5.3Cobalt Chloride (CoCl 2·6H 2O).
5.4Hydrochloric Acid (sp gr 1.19)—Concentrated hydro-chloric acid (HCl).
5.5Potassium Chloroplatinate (K 2PtCl 6).
6.Platinum-Cobalt Reference Standards
6.1Platinum-Cobalt Stock Solution —Dissolve 1.245g of potassium chloroplatinate (K 2PtCl 6)and    1.00g of cobalt chloride (CoCl 2·6H 2O)in water.Carefully add 100mL of hydrochloric acid (HCl,sp gr 1.19)and dilute to 1L with water.The absorbance of the 500platinum-cobalt stock solu-tion in a cell havi
ng a 10-mm light path,with reagent water in a matched cell as the reference solution,8must fall within the limits given in Table 1.
N OTE 3—This stock solution is commercially available from reputable chemical suppliers.
6.2Platinum-Cobalt Standards —From the stock solution,prepare color standards in accordance with Table 2by diluting the required volumes to 100mL with water in the Nessler
5
See NIST Letter Circular LC-1017.
6
The sole source of supply of the unit known to the committee at this time is Scientific Glass and Instruments,Inc.,P.O.Box 6,Houston,TX 77001.If you are aware of alternative suppliers,please provide this information to ASTM Interna-tional Headquarters.Your comments will receive careful consideration at a meeting of the responsible technical committee,1which you may attend.7
Reagent Chemicals,American Chemical Society Specifications ,American Chemical Society,Washingto
n,DC.For suggestions on the testing of reagents not listed by the American Chemical Society,see Analar Standards for Laboratory Chemicals ,BDH Ltd.,Poole,Dorset,U.K.,and the United States Pharmacopeia and National Formulary ,U.S.Pharmacopeial Convention,Inc.(USPC),Rockville,MD.8
See the manufacturer’s instruction manual for complete details for operating the spectrophotometer.
TABLE 1Absorbance Tolerance Limits For No.500Platinum-Cobalt Stock Solution
Wavelength,nm
Absorbance 4300.110to 0.1204550.130to 0.1454800.105to 0.120510
0.055to 0.065
TABLE 2Platinum-Cobalt Color Standards
Color Standard
Number
Stock Solution,
mL
Color Standard
Number
Stock Solution,
mL
5170141021002015315030204200402552505030630060357350704084008050104509060
12
500
100A
A
This is platinum-cobalt color No.10in Guide D 365.
TABLE 3Platinum-Cobalt Color Standards for Very Light Colors
Color Standard
Number
Stock Solution,
mL
Color Standard
Number
Stock Solution,
mL
10.209  1.8020.4010  2.0030.6011  2.2040.8012  2.405  1.0013  2.606  1.2014  2.807  1.4015
3.00
8
1.60
tubes.Cap the tubes and seal the caps with shellac or a waterproof cement.When properly sealed and stored,these standards are stable for at least 1year and do not degrade markedly for 2years.9
6.2.1For a more precise measurement of light colors below 15platinum-cobalt,prepare color standards from the stock solution in accordance with Table 3by diluting the required volumes to 100mL with water in the Nessler tubes.Use a semi-microburet for measuring the required amount of stock solution.
7.Procedure
7.1Introduce 100mL of specimen into a Nessler tube,passing the specimen through a filter if it has any visible turbidity.Cap the tube,place in the comparator,and compare with the standards.
8.Report
8.1Report as the color the number of the standard that most nearly matches the specimen.In the event that the color lies midway between two standards,report the darker of the two.8.2If,owing to differences in hue between the specimen and the standards,a definite match cannot be obtained,report the range over which an apparent match is obtained,and report the material as “off-hue.”
9.Precision
9.1Color Samples with Pt-Co Color Greater than 2510:9.1.1These precision statements are based upon an inter-laboratory study in which six platinum-cobalt standards having values of 25,75,170,265,385,and 475were prepared in accordance with the instructions given in Section 6of this test method and were given coded labels.These solutions were tested by one analyst in each of ten different laboratories making a single observation on one day and then repeating the
observation on a second day.The analysts were requested to estimate the color to the nearest one unit for solutions below 40platinum-cobalt,to the nearest five units for solutions between 40and 100platinum-cobalt and to the nearest ten units for solutions above 100platinum-cobalt.Based on the results of this interlaboratory study,the following criteria,calculated according to RR-D02-1007,should be used for judging the acceptability of results at the 95%confidence level when the results are obtaine
d under optimum conditions where the hue of the sample matches exactly the hue of the standards.Poor precision will be obtained in varying degrees as the hue of the sample departs from that of the standards.
9.1.1.1Repeatability —Two results,obtained by the same analyst should be considered suspect if they differ by more than:
r =0.027(X +92)platinum-cobalt units
where X is the average of the two results.
9.1.1.2Reproducibility —Two results,obtained by analysts in different laboratories,should be considered suspect if they differ by more than:R =0.087(X +92)platinum-cobalt units where X is the average of the two results.
9.1.1.3Table 4shows precision values for samples with Pt-Co Color of greater than 25.
9.2Color Samples with Pt-Co Color Less than 2511:
9.2.1The results of two interlaboratory studies were pooled to give precision values calculated accordi
ng to RR-D02-1007.One study of glycols included 4samples and 7laboratories;the other study included 5samples and 6laboratories.Based on the pooled repeatability and reproducibility standard deviations,the following criteria should be used for judging,at the 95%confidence level,the acceptability of results obtained on samples with less than 25Pt-Co Color.
9.2.1.1Reapeatability —Two results,each the mean of du-plicates,obtained by the same operator on different days should be considered suspect if they differ by more than two platinum-colbalt units.
9.2.1.2Reproducibility —Two results,each the mean of duplicates,obtained by operators in different laboratories,should be considered suspect of they differ by more than seven platinum-cobalt units.
9.3Bias —The test procedure has no bias because the value of the test result is defined only in terms of the test method.10.Keywords
10.1clear liquids;color;platinum-cobalt color scale
9
Scharf,W.W.,Ferber,K.H.,and White,R.G.,“Stability of Platinum-Cobalt Color Standards,”Materials Research and Standards ,V ol 6,No.6,June 1966,pp.302–304.10
Supporting data are available from ASTM International Headquarters.Request RR:D01-1024and RR:D02-1007.
11
These precision statements are based on interlaboratory studies conducted by Committee E-15on Industrial Chemicals on samples of ethylene glycol and methanol as reported in Test Methods E 202,E 346,and research reports RR:E15-28,and D01-1108.
TABLE 4Precision Values for Greater than 25Pt-Co Color
Color (Pt-Co units)
Repeatability,r
Reproducibility,R
253107551516572226510313851341475
16
49
SUMMARY OF CHANGES
Committee D01.35has identified the location of selected changes to this standard since the last issue (D1209–00)that may impact the use of this standard.
(1)Added reference to Practice E29in1.3of the Scope section.(2)Added Practice E29to list of Referenced Documents.
(3)Removed self-reference in Section2.
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