1、Designation: D7622 10Standard Test Method forTotal Mercury in Crude Oil Using Combustion and DirectCold Vapor Atomic Absorption Method with ZeemanBackground Correction1This standard is issued under the fixed designation D7622; the number immediately following the designation indicates the year ofori
2、ginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the procedure to determine thetotal me
3、rcury content in a sample of crude oil. This test methodcan be used for total mercury determination in natural andprocessed liquid and oil products (gasoline, naphtha, etc.).1.2 This test method may be applied to samples containingbetween 5.0 to 350 ng/mL of mercury. The results may beconverted to m
4、ass basis.1.3 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.4 WARNINGMercury has been designated by manyregulatory agencies as a hazardous material that can causecentral nervous system, kidney and liver damage. Mercury, orit
5、s vapor, may be hazardous to health and corrosive tomaterials. Caution should be taken when handling mercury andmercury containing products. See the applicable product Ma-terial Safety Data Sheet (MSDS) for details and EPAswebsitehttp:/www.epa.gov/mercury/faq.htmfor addi-tional information. Users sh
6、ould be aware that selling mercuryand/or mercury containing products into your state or countrymay be prohibited by law.1.5 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-pr
7、iate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D1193 Specification for Reagent WaterD4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD4175 Terminology Relating to Petroleum, Petro
8、leumProducts, and LubricantsD4177 Practice for Automatic Sampling of Petroleum andPetroleum ProductsD6299 Practice for Applying Statistical Quality Assuranceand Control Charting Techniques to Evaluate AnalyticalMeasurement System PerformanceD6300 Practice for Determination of Precision and BiasData
9、for Use in Test Methods for Petroleum Products andLubricantsD6792 Practice for Quality System in Petroleum Productsand Lubricants Testing LaboratoriesD7482 Practice for Sampling, Storage, and Handling ofHydrocarbons for Mercury AnalysisD7623 Test Method for Total Mercury in Crude Oil UsingCombustion
10、-Gold Amalgamation and Cold Vapor AtomicAbsorption Method3. Terminology3.1 For definitions of terms used in this test method, refer toTerminology D4175.4. Summary of Test Method4.1 Controlled heating following thermal decomposition ofthe analysis sample in air is used to liberate mercury. Thesample
11、is placed into the sample boat, which is inserted in thefirst chamber of the atomizer, where the sample is heated atcontrolled temperature at 300 to 500C (depending on theselected operation mode). The mercury compounds are evapo-rated and partially dissociated forming elemental mercuryvapor. Mercury
12、 and all decomposition products are carried tothe second chamber of the atomizer heated to about 700 to750C (mercury reduction takes place on the surface of heatingNiCr coil, thus no catalyst is required). Mercury compoundsare totally dissociated, and the organic matrix of the sample isburnt out. Co
13、ntinuously flowing air carries mercury and othercombustion products through absorbance analytical cell heatedup to 750C positioned in the light path of double-wave cold1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibili
14、ty of SubcommitteeD02.03 on Elemental Analysis.Current edition approved May 1, 2010. Published July 2010.2For 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 standar
15、ds Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.vapor Zeeman atomic absorption spectrophotometer. The mer-cury resonance line 253.65 nm is split to several components,one of those falling w
16、ithin the mercury absorbance line(analytical line) profile and another one lying outside (refer-ence line). Difference between the intensities of these com-pounds is proportional to number of mercury atoms in theanalytical cell. Absorbance peak area or peak height is afunction of the mercury concent
17、ration.NOTE 1Mercury and mercury salts can be volatized at low tempera-tures. Precautions against inadvertent mercury loss should be taken whenusing this test method.5. Significance and Use5.1 The emission of mercury during crude oil refining is anenvironmental concern. The emission of mercury may a
18、lsocontaminate refined products and form amalgams with metals,such as aluminum.5.2 When representative test portions are analyzed accord-ing to this procedure, the total mercury is representative ofconcentrations in the sample.6. Apparatus6.1 General configuration of the instrument shall have thefol
19、lowing functional components: temperature controlledsample heating and decomposition furnace, measuring cu-vettes, mercury lamp placed in strong magnetic field, polariza-tion modulator to separate analytical and reference lines, anddetector. The following requirements are specified for allapproved i
20、nstruments.3NOTE 2The approval of an instrument with respect to these functionsis paramount to this test method, since such approval tacitly providesapproval of both the materials and the procedures used with the system toprovide these functions.6.1.1 Zeeman Mercury SpectrometerAtomic absorptionspec
21、trometer with Zeeman background correction, operatingwith the mercury resonance absorption wavelength of253.7 nm.6.1.2 The atomizer shall have a decomposition tube, whichshall be operated at a temperature high enough to completelydecompose the sample. The suggested operating temperature isat least 6
22、00C.6.1.3 The heated analytical cell shall be capable to preventmercury loses due to deposition to cold parts and to preventmercury recombination with chlorine. The suggested operatingtemperature of the analytical cell is at least 700C.6.1.4 The system may contain a computer for controllingthe vario
23、us operations of the apparatus, for recording data, andfor reporting results.6.2 Analytical Balance, with a sensitivity of 0.1 mg.6.3 Sample Boats, quartz, stainless steel, porcelain, or othermaterial as recommended and convenient size suitable for usein the instrument being used.6.4 Micropipetters,
24、 one or more units of variable volume tocover a range from 10 to 250 L, NIST traceable. Appropri-ately sized tips should also be available.6.5 Ultrasonic HomogenizerA bath-type ultrasonic ho-mogenizer is used to dissociate particulate mercury and thor-oughly mix the sample.6.6 Glassware, volumetric
25、flasks of various capacities andClass A pipettes of various capacities. All glassware must bethoroughly cleaned with freshly prepared, 10 % nitric acidsolution and rinsed with water. It is recommended that dedi-cated glassware be maintained to minimize cross-contamination.7. Sample7.1 Obtain the ana
26、lysis sample of crude oil in accordancewith Practice D4057 or D4177. Crude oil should be collectedin a manner that ensures a representative of the bulk containeris obtained.7.2 To prevent loss of mercury during storage and handlingof samples, follow Practice D7482. Samples should not becollected in
27、metal containers. Precleaned, glass volatile organicanalysis (VOA) vials have been found to be suitable for thispurpose.7.3 Samples should be analyzed as quickly as possible aftercollection. Sample containers should be kept tightly cappedand stored in a cool location.8. Reagents and Materials8.1 Pur
28、ity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents conform to the specifications of the Committee onAnalytical Reagents of the American Chemical Society wheresuch specifications are available.4Other grades may be used,provide
29、d it is first ascertained that the reagent is of sufficientlyhigh purity to permit use without lessening the accuracy of thedetermination.8.2 Purity of WaterUnless otherwise indicated, referenceto water shall be understood to mean reagent water conformingto Type II of Specification D1193. Water must
30、 be checked forpotential mercury contamination before use.8.3 A standard sample of mercury ions solution (concentra-tion1= 1.0 g/L).8.4 Certified Reference Materials (CRMs)Use CertifiedReference Material (CRM) crude oils with mercury values forwhich confidence limits are issued by a recognized certi
31、fyingagency such as the National Institute of Standards and Tech-nology (NIST).8.5 Nitric Acid, concentrated, Trace Metal Grade or better.8.6 Combustion Reagents, activated charcoal, 30 3 50mesh.8.7 Potassium Dichromate Solution, 4 % (mass)Place a4 g portion of potassium dichromate in a volumetric f
32、lask3The sole source of supply of the apparatus known to the committee at this timeis Lumex model RA 195 available from Ohio Lumex Company, 9263 RavennaRoad, Unit A-3, Twinsburg, OH 44087. If you are aware of alternative suppliers,please provide this information to ASTM International Headquarters. Y
33、our com-ments will receive careful consideration at a meeting of the responsible technicalcommittee,1which you may attend.4Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemi
34、cal Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.D7622 102(volume of 100 mL), dissolve in distilled water and dilute withthe distilled water up
35、to the mark. The solution is to be storedin a reservoir made of dark glass with a plug stopper. Storagetime is 3 months.8.8 Dilution SolutionPlace 500 to 600 mL of distilledwater in a heat-resistant glass and pour in carefully 50 mL ofconcentrated nitric acid (d = 1.37 g/mL). Stir constantly whilepo
36、uring in the acid. Transfer to a volumetric flask of 1000 mLvolume, add 5 mL of 4 % potassium dichromate solution andadd up with distilled water up to the mark. The solution is to bestored in a reservoir made of dark glass with a plug stopper.Storage time is 3 months.8.9 All CRMs, reference crude oi
37、ls, or calibrating agentsshall have precision values of less than or equal to methodrepeatability. Such CRMS, reference crude oils, or calibratingagents must be stable and must be mixed thoroughly beforeeach use.9. Preparation of Standards9.1 Working Standard SetPrepare a set of standards thatare ap
38、propriate to the range settings on the instrument in use.An example of such a set follows:9.1.1 Place 30 mL of a dilution solution in a volumetricflask (100 mL volume). Then place 2 mL of a standard sampleof mercury ions NIST or other standard reference materialissuing bodies traceable standard solu
39、tion (concentration1=1.0 g/L). Bring the contents of the volumetric flask up to themark with the dilution solution and stir thoroughly. This resultsin a mercury concentration of 20 mg/L(2). The solution may bestored in a refrigerator during 6 months.9.1.2 Place 30 mL of a dilution solution in a volu
40、metricflask (100 mLvolume). Then place 10 mLof a standard sampleof mercury solution2= 20 mg/L. Bring the contents of theretort up to the mark with the dilution solution and stirthoroughly. This makes a 2 mg/L = 2000 g/L (3). The solutionmay be stored in a refrigerator during 3 months.9.1.3 Place 30
41、mL of a dilution solution in a volumetricflask (100 mLvolume). Then place 10 mLof a standard sampleof mercury solution3= 2.0 mg/L. Bring the contents of theretort up to the mark with the dilution solution and stirthoroughly. This makes a 200 g/L (4). The solution may bestored in a refrigerator durin
42、g 3 months.9.1.4 Place 30 mL of a dilution solution in a volumetricflask (100 mLvolume). Then place 10 mLof a standard sampleof mercury solution4= 200 g/L.) Bring the contents of theretort up to the mark with the dilution solution and stirthoroughly. This makes a 20 g/L (5). The solution may bestore
43、d in a refrigerator during 1 month.NOTE 3The standard preparation procedure given in Test MethodD7623 is also acceptable.10. Instrument Preparation10.1 Assemble the instrument and check for leaks in thesystem in accordance with the manufacturers instructions.Follow the instrument manufacturers recom
44、mended procedureto optimize the performance of the instrument.10.2 Choose the proper sample heating mode based uponthe expected mercury concentration and the sample matrix.10.3 Samples boats and charcoal should also be pretreatedin the muffle furnace before initial use.10.4 A satisfactory blank shou
45、ld have stable response and asignal that corresponds to the equivalent of 3 ng/g mercury.11. Calibration Procedure11.1 Spread approximately 0.2 g of charcoal in the bottomof a cooled sample boat. Using a micropipetter and tip, transfer100 L of the dilution solution on to a charcoal media. Placethe s
46、ample boat into the furnace area and start the instrument.Repeat this step four times to obtain blank value.11.2 Spread approximately 0.2 g of charcoal over bottom ofa cooled sample boat. Using a micropipetter and tip, transfer100 L of standard solution 200 g/L on to a charcoal media.Place the sampl
47、e boat into the furnace area and start theinstrument. Repeat this step for 20 and 2000 g/L to span theeffective range of response. Create a calibration curve byassigning the appropriate mass of mercury introduced into theinstrument with the corresponding response. Follow manufac-turers recommendatio
48、ns to use available software tools thatautomate the calculations.11.3 Periodic Calibration Verification andRecalibrationIn accordance with Practice D6792, analyze acontrol sample on a periodic basis. Results obtained for thecontrol sample must be within established limits. If a controlcheck sample r
49、esult is out of control, all results obtained sincethe last successful control check must be rejected and thecalibration procedure repeated.12. Procedure12.1 Place crude oil sample containers in an ultrasonichomogenizer for approximately fifteen minutes just prior toanalysis. Keep the water in the bath at ambient temperature byadding a few ice chips as the temperature rises. The homog-enization step dissociates particulate mercury and promotes amore stable suspension.12.2 Remove sample boat and reagents (if required) frommuffle furnace and allow to c
