1、Designation: D 6258 04An American National StandardStandard Test Method forDetermination of Solvent Red 164 Dye Concentration inDiesel Fuels1This standard is issued under the fixed designation D 6258; the number immediately following the designation indicates the year oforiginal adoption or, in the
2、case of revision, the year 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. Scope*1.1 This test method covers the procedure for determiningthe concentration of dye Solvent
3、Red 164 in commerciallyavailable diesel and burner fuels using visible spectroscopy.NOTE 1This test method is suitable for all No. 1 and No. 2 grades inSpecifications D 396 and D 975 and for grades DMA and DMB inSpecification D 2069.1.2 The concentration ranges specified for the calibrationstandards
4、 are established in response to the Internal RevenueService dyeing requirements which state that tax-exempt dieselfuel satisfies the dyeing requirement only if it contains the dyeSolvent Red 164 (and no other dye) at a concentrationspectrally equivalent to 3.9 lb of the solid dye standard SolventRed
5、 26 per thousand bbl (11.1 mg/L) of diesel fuel.1.3 The values stated in SI units are to be regarded as thestandard.1.4 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
6、 safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 396 Specification for Fuel OilsD 975 Specification for Diesel Fuel OilsD 2069 Specification for Marine Fuels3D 3699 Specification for KerosineD 4057 Pract
7、ice for Manual Sampling of Petroleum andPetroleum ProductsE 131 Terminology Relating to Molecular SpectroscopyE 169 Practices for General Techniques of Ultraviolet-Visible Quantitative AnalysisE 275 Practice for Describing and Measuring Performanceof Ultraviolet, Visible, and Near-Infrared Spectroph
8、otom-etersE 288 Specification for Laboratory Glass Volumetric FlasksE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE 969 Specification for Glass Volumetric (Transfer) Pipettes2.2 Other Document:26 CFR 48.4082-1(b) Federal Excise Tax Regulation3. Term
9、inology3.1 Definitions:3.1.1 For definitions of terms used in this test method, referto Terminology E 131.4. Summary of Test Method4.1 The absorbance of each sample is recorded over aspecified wavelength range, and the scan is analyzed usingderivative analysis software to determine the dye concentra
10、-tion.4.2 Derivative analysis methodology is employed to mini-mize interferences caused by variations in the color andcomposition of the fuel samples regularly tested using this testmethod.4.2.1 Naturally occurring diesel test fuels range in colorfrom water white to nearly black, and many of the sam
11、plestested using this test method have also had used oils and otherproducts blended with them. These variations in color andcomposition have a significant effect upon absorbance charac-teristics of the samples in the region of the visible spectrumwhere azo dyes absorb. Standard operating procedures
12、tocorrect for these background variations would involve runninga neat (undyed) sample and subtracting out the backgroundabsorbance. In most situations involved with the application ofthis test method, however, neat material is not available, so nobackground corrections can be made.4.2.2 The second d
13、erivative of the absorbance of these dyesin the visible region is a function of the fine structure of thedyes absorbance peak (versus its height or area) and isrelatively unaffected by changes in background absorbance.1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Prod
14、ucts and Lubricants and is the direct responsibility of SubcommitteeD02.05 on Properties of Fuels, Petroleum Coke and Carbon Material.Current edition approved Nov. 1, 2004. Published November 2004. Originallyapproved in 1998. Last previous edition approved in 2003 as D 625898(2003)e1.2For referenced
15、 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.3Withdrawn.1*A Summary of Changes section appears at the end of this standar
16、d.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.Further, the specific sections (maxima and minima) of thesecond derivative spectra employed for this analysis are afunction of the fine structure of the top of the absorbance curvewhic
17、h has been found to be unique to the azo dyes.5. Significance and Use5.1 This test method was developed to provide for theenforcement of 26 CFR 48.4082-1(b), which mandates that alltax-exempt diesel fuels be dyed with an amount of Solvent Red164 at a concentration that is spectrally equivalent to 3.
18、9 lb/103bbl (11.1 mg/L) of Solvent Red 26. It is employed to verify thatthe correct amount of Solvent Red 164 is being added totax-exempt product at terminals or refineries prior to sale, andto detect the presence of Solvent Red 164 in taxed productintended for on-road use.5.1.1 Solvent Red 26 is th
19、e azo dye shown in Fig. 1.Itisthestandard against which the concentration of Solvent Red 164 ismeasured because it is available in a certified pure form.Solvent Red 164 is identical in structure to Solvent Red 26except that it has hydrocarbon (alkyl) chains incorporated toincrease its solubility in
20、diesel and burner fuels. The exactcomposition of Solvent Red 164 will vary from manufacturerto manufacturer and lot to lot depending upon the extent ofalkylation that occurs during production; however, its visiblespectrum is virtually identical to the spectrum of Solvent Red26. Solvent Red 164 is em
21、ployed in the field (instead ofSolvent Red 26) to dye tax-exempt diesel and burner fuelsbecause of its higher solubility and relatively low cost.6. Apparatus6.1 Spectrophotometer, equipped with automated scanning,background correction, and electronic data storage capabilities,and the ability to auto
22、matically record absorbance or transmit-tance of solutions in the spectral region from 400 to 800nanometers (nm) with a spectral slit width of 1.0 nm or less(Note 2). Wavelength measurements shall be repeatable andknown to be accurate to within 60.2 nm or less at deuteriumpeak 656.1 nm. In the absor
23、bance range from 0.01 to 1.0,absorbance measurements shall have a photometric accuracy of60.005 or less and a photometric repeatability of 60.002 orless.NOTE 2Instruments having different specifications, for example,minimum slit width 2 to 4 nm, no data storage, diode array spectropho-tometers, and
24、so forth, may be used if they provide demonstrablyequivalent results. Equivalence can be demonstrated by successful (withinreproducibility limits) participation in inter- or intra-laboratory studiesusing this test method.6.1.1 For applicable general techniques and methods oftesting spectrophotometer
25、s to be used in this test method, referto Practices E 169 and E 275.6.2 Sample Cells (Cuvettes), one or more fused silica orglass cells having sample path length of 1.0 cm.6.3 Analytical Balance, 0.1 mg sensitivity, 60.05 mg pre-cision.6.4 Volumetric Pipettes, 1, 2, 3, 4, and 5 mL, Class A,according
26、 to Specification E 969.6.5 Volumetric Flasks, 100 mL and 250 mL, Class A,borosilicate glass, according to Specification E 288.7. Reagents7.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specific
27、ations of the Commit-tee on Analytical Reagents of the American Chemical Societywhere such specifications are available.4Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.7.2 S
28、olvent Red 26 (Dye Standard)Dye, Color IndexSolvent Red 26, 1-2,5-dimethyl-4-(2-methylphenyl)azophenylazo-2-naphthol, Chemical Abstract Services Reg-istry No. 4477-79-6, dry powder with certified purity, andmaximum absorbance at 512 6 20 nm.7.3 Kerosine1-K, water-white, conforming to Specifica-tion
29、D 3699, and having a maximum absorbance against air of0.08 absorbance units over the wavelength range 450 to 750nm (1.0 cm cell, 120 nm/min scan rate, slit width 1.0 nm).(WarningFlammable; harmful if swallowed, inhaled, orbrought into contact with skin or eyes.)7.4 Xylene(WarningExtremely flammable;
30、 harmful ifswallowed, inhaled, or brought into contact with skin or eyes.)8. Sampling8.1 Use the principles of Practice D 4057 in acquisition oftest sample(s).8.2 Precautions must be taken to shield the samples fromsunlight prior to analysis.NOTE 3Studies have shown that exposure to direct sunlight
31、will showa decrease in dye concentration over time.9. Calibration and Standardization9.1 Preparation of Stock Standard:9.1.1 Solvent Red 26Weigh approximately 0.0750 g of thedye standard to the nearest 0.1 mg on an analytical balance,quantitatively transfer the dye to a 250 mL volumetric flask,and d
32、ilute to mark with xylene. Mix the prepared solutionthoroughly.4Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemicals,
33、BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.FIG. 1 Structure of Solvent Red 26D62580429.1.2 Determine the exact concentration of dye in the stockstandard using the following equation:C 5M! P! 1000!0
34、.250(1)where:C = concentration of active dye ingredient in the stockstandard, mg/L,M = mass of certified dye standard used in preparing thestock standard, g, andP = purity of certified dye standard used in preparing thestock standard, purity %/100, for example, for a 99.0% Solvent Red 26 material, P
35、 = 0.99.9.1.3 Store the stock standard in tightly capped/sealedbrown glass bottles and store in a dark place when not in useto prevent deterioration.9.2 Preparation of Working Calibration Standards:9.2.1 Pipet the volumes of the stock standard specifiedbelow into separate 100 mL volumetric flasks an
36、d dilute tovolume with kerosine.Volume of Stock Approximate ConcentrationStandard/100 mL of Working Standards0.0 mL 0 mg/L1.0 mL 3 mg/L2.0 mL 6 mg/L3.0 mL 9 mg/L4.0 mL 12 mg/L5.0 mL 15 mg/L9.2.2 Determine the exact concentration of dye in eachworking standard using the following equation:Cs 5V!Cm!10
37、0(2)where:Cs = concentration of each working standard, mg/L,V = volume of stock standard, mL, andCm = concentration of active dye in stock standard, mg/L.9.2.3 Store the working calibration standards in tightlycapped/sealed brown glass bottles and store in a dark placewhen not in use to prevent dete
38、rioration.9.3 Using a clean 1.0 cm sample cell, scan each of theworking standards against air (empty reference sample com-partment) from 450 nm to 750 nm, recording the absorbancefor each using a scan rate of 120 nm/min, maximum datarecording interval of 0.11 nm, and a maximum slit width of 1.0nm.NO
39、TE 4Other instrument conditions may be used if they can bedemonstrated to give equivalent results to this test method (see Note 2).9.4 Using derivative analysis software, calculate and plotthe second derivative spectra for each standard over thiswavelength range using an instrument noise level dampe
40、ningsetting of sufficient level to provide a smooth second derivativecurve.9.5 Measure the amplitude difference for the maximum andminimum listed below:Solvent Red 26: 538 6 20 nm (peak max, Fig. 2)561 6 20 nm (peak min, Fig. 2)NOTE 5Specific amplitude units employed will vary, depending oninstrumen
41、tation or software used, or both.10. Procedure10.1 Using a clean 1.0 cm sample cell, scan the sampleagainst air (empty reference sample compartment) from 450nm to 750 nm using the same instrument settings employed forthe working standards and record the absorbance.10.2 Using derivative analysis soft
42、ware and the same noiselevel dampening settings used in 9.4, calculate and plot thesecond derivative spectrum of the sample.10.3 Measure the amplitude difference between the deriva-tive maximum and minimum specified in 9.5 (see Note 5).10.3.1 The wavelengths of the derivative minima andmaxima for th
43、e dye in actual diesel fuel samples normally varyfrom those observed for the working standards due to varia-tions in the composition of the Solvent Red 164 dye used andsample matrix effects. On instruments that automaticallyrecord amplitudes at preset wavelengths, adjustments must beFIG. 2 Second De
44、rivative Scans of Solvent Red 26 Dye in KerosineD6258043made to compensate for this shift to ensure that actualminimum and maximum amplitudes are used in determiningamplitude differences.11. Calculation11.1 Prepare a calibration curve, plotting the amplitudedifference for each working calibration st
45、andard on the y axisversus the dye concentration on the x axis.11.2 Determine the concentration of dye in the sample bycomparing the amplitude difference measured in 10.3 for thesample against the calibration curve.11.2.1 Computer systems/software having appropriate mul-tipoint calibration program c
46、apabilities may be used instead ofa manual interpolation from calibration curves.11.3 Report the dye concentration results for the sample inmg/L to one decimal place, for example, 11.1 mg/L.12. Precision and Bias512.1 PrecisionThe precision of the test method, as ob-tained by statistical examination
47、 of inter- and intra-laboratorytest results obtained in accordance with the requirements ofPractice E 691, is as follows:12.1.1 RepeatabilityWithin-laboratory precision, a quan-titative expression of the random error associated with a singleoperator in a given laboratory obtaining repetitive results
48、 withthe same apparatus under constant operating conditions onidentical test material. It is defined as the difference betweentwo such results at the 95 % confidence level. The repeatabilityexpression is valid for the concentration range covered by theinterlaboratory study samples (1.20 to 18.2 mg/L
49、).5Repeatability r! 5 0.1847 x!0.5(3)where:x = mean dye concentration (mg/L) of two results from thesame laboratory.12.1.2 ReproducibilityBetween-laboratory precision, aquantitative expression of the random error associated withdifferent operators using different test apparatus in differentlaboratories and obtaining test results when applying the samemethod. It is defined as the 95 % confidence limit for thedifference between two such single and independent results.The reproducibility expression is valid for the concentrationrange covered by the interlabor
