1、Designation: D7623 10Standard Test Method forTotal Mercury in Crude Oil Using Combustion-GoldAmalgamation and Cold Vapor Atomic Absorption Method1This standard is issued under the fixed designation D7623; the number immediately following the designation indicates the year oforiginal adoption or, in
2、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 procedures to determine thetotal mercury content in a sa
3、mple of crude oil.1.2 The test method may be applied to crude oil samplescontaining between 5 to 400 ng/mL of mercury. The resultsmay be converted to mass basis, and reported as ng/g ofmercury.1.3 The values stated in SI units are to be regarded asstandard. No other units of measurement are included
4、 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, orits vapor, may be hazardous to health and corrosive tomaterials. Caution should be taken when handling mercury andmercu
5、ry 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 should be aware that selling mercuryand/or mercury containing products into your state or countrymay be prohibited by l
6、aw.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-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Reference
7、d Documents2.1 ASTM Standards:2D1193 Specification for Reagent WaterD4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD4175 Terminology Relating to Petroleum, PetroleumProducts, and LubricantsD4177 Practice for Automatic Sampling of Petroleum andPetroleum ProductsD6299 Practice fo
8、r Applying Statistical Quality Assuranceand Control Charting Techniques to Evaluate AnalyticalMeasurement System PerformanceD6300 Practice for Determination of Precision and BiasData for Use in Test Methods for Petroleum Products andLubricantsD6792 Practice for Quality System in Petroleum Productsan
9、d Lubricants Testing LaboratoriesD7482 Practice for Sampling, Storage, and Handling ofHydrocarbons for Mercury AnalysisD7622 Test Method for Total Mercury in Crude Oil UsingCombustion and Direct Cold Vapor Atomic AbsorptionMethod with Zeeman Background Correction3. Terminology3.1 For definitions of
10、terms used in this standard, refer toTerminology D4175.4. Summary of Test Method4.1 Controlled heating of the analysis sample in oxygen isused to liberate mercury. The sample is heated to dryness in theinstrument and then thermally (at about 700C) and chemicallydecomposed. The decomposition products
11、 are carried by flow-ing treated air to the catalytic section of the furnace (at about850C), where oxidation is completed. The decompositionproducts are carried to a gold amalgamator that selectivelytraps mercury. After the system is flushed with oxygen toremove any remaining decomposition products
12、other thanmercury, the amalgamator is rapidly heated to about 600C,releasing mercury vapor. Flowing oxygen carries the mercuryvapor through absorbance cells positioned in the light path of1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the
13、 direct responsibility 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,
14、refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.single wavelength cold vapor atomic absorption spectropho-tometer. Absorbance peak height or peak area, as a function ofm
15、ercury concentration, is measured at 253.65 nm.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 anenvironmenta
16、l concern. The emission of mercury may alsocontaminate 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 There are several
17、 configurations of the instrumentalcomponents that can be used satisfactorily for this testmethod.3Functionally, the instrument shall have the followingcomponents: sample heating furnace, decomposition furnace,gold amalgamator, amalgamator furnace, measuring cuvettes,mercury lamp, and detector. The
18、following requirements arespecified for all approved instruments.NOTE 2Approval of an instrument with respect to these functions isparamount 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
19、 The instrument shall be capable of drying the sampleonce it is weighed and introduced.6.1.2 The instrument shall have a decomposition tube,which shall be operated at a temperature high enough tocompletely decompose the sample. The suggested operatingtemperature is at least 700C.6.1.3 The catalyst s
20、hall be capable of completing the oxi-dation of the sample and trapping halogens as well as nitrogenand sulfur oxides. The suggested operating temperature of thecatalytic tube is 850C.6.1.4 The instrument shall contain one or more gold amal-gamator fixed to an inert material and shall be capable oft
21、rapping all mercury.6.1.5 The amalgamator shall contain a furnace capable ofrapidly heating the amalgamator to release all trapped mercury.6.1.6 The instrument shall have an absorption cell throughwhich the elemental mercury released from the gold amalgam-ator flows. The cell shall be heated to avoi
22、d any condensationof water or other decomposition products.6.1.7 The light source for the atomic absorption processshall be a low pressure mercury lamp.6.1.8 Anarrow bandpass interference filter or monochroma-tor, capable of isolating the 253.65 nm mercury line, shall beused.6.1.9 The system may con
23、tain a computer for controllingthe various operations of the apparatus, for recording data, andfor reporting results.6.2 Analytical Balance, with a sensitivity of 0.1 mg.6.3 Sample Combustion Boats, porcelain, quartz, or othermaterial as recommended and of convenient size suitable foruse in the inst
24、rument being used.6.4 Crucibles, porcelain, high-form, 40 mL capacity orsuitable size for heating reagent in furnace.6.5 Micropipettes, one or more units of variable volumes tocover a range of 10 to 250 L. Appropriately sized tips shouldalso be available.6.6 Ultrasonic HomogenizerA bath type ultraso
25、nic ho-mogenizer is used to dissociate particulate mercury and thor-oughly mix the sample.6.7 Electric Muffle Furnace, capable of maintaining 750 625C and sufficiently large to accommodate the sample boatsand reagent containers.6.8 Glassware, class A, volumetric flasks and pipettes ofvarious capacit
26、ies. All glassware must be thoroughly cleanedwith freshly prepared 10 % nitric acid solution and rinsed withwater. It is recommended that dedicated glassware be main-tained to minimize cross contamination.7. Sample7.1 Obtain the analysis sample of crude oil in accordancewith Practice D4057 or D4177.
27、 Crude oil should be collectedin a manner that ensures a representative sample from the bulkcontainer is obtained.7.2 To prevent loss of mercury during storage and handlingof samples, follow Practice D7482. Sample should not becollected in metal containers. Precleaned, glass volatile organicanalysis
28、 (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 free from direct sunlight.8. Reagents8.1 Purity of ReagentsReagent grade chemicals shall beu
29、sed 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,provided it is first ascertained that the reagent is of
30、 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 be checked forpotential mercury contamination b
31、efore use.3The sole source of supply of the apparatus known to the Committee at this timeis Nippon SP3D model available from Nippon Instrument Corp., 14-8, Akaoji-cho,Takatsuki-shi, Osaka 569-1146, Japan. If you are aware of alternative suppliers,please provide this information to ASTM International
32、 Headquarters. Your com-ments will receive careful consideration at a meeting of the responsible technicalcommittee, which you may attend.4Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by th
33、e American Chemical 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.D7623 1028.3 Air or OxygenFiltered, purified air or high purityoxygen, as speci
34、fied by the instrument manufacturer, shall beused. The air must be mercury-free. Some instruments processincoming combustion air with filters and driers before it is usedfor the analysis.8.4 Certified Reference Materials (CRMs)Use CertifiedReference Material (CRM) crude oils with mercury values forw
35、hich confidence limits are issued by a recognized certifyingagency such as the National Institute of Standards and Tech-nology (NIST).8.4.1 All CRMs, reference crude oils, or calibrating agentsmust have precision values of less than or equal to methodrepeatability. Such CRMS, reference crude oils, o
36、r calibratingagents must be stable and must be mixed thoroughly beforeeach use.8.5 L-cysteine, 99+ % purity. Reagents must be evaluatedfor mercury content by checking blank solutions for responseon the instrument.8.6 Nitric Acid, concentrated, Trace Metal Grade or better.8.7 Mercuric Chloride, 99.99
37、+ % purity. A commerciallyprepared mercury stock standard may be used.8.8 Phosphate Buffer, pH 7.2. Some phosphate buffers usemercury compounds as preservative. The buffer must bemercury-free. Check with the instrument manufacturer forsources of suitable buffer.8.9 Combustion Reagents:8.9.1 Additive
38、 1 or B (Aluminum Oxide), ground, availablefrom instrument manufacturer.8.9.2 Additive 2 or M, 40/60 m % mixture of calciumhydroxide and sodium carbonate available from instrumentmanufacturer.8.9.3 Calcium Hydroxide, 99.5 % minimum purity.8.9.4 Sodium Carbonate, 99.99 % minimum purity.8.10 Glassine
39、Weighing Paper.9. Preparation of Mercury Standards9.1 L-cysteine Solution, 0.001 m %Weigh approximately0.010 g of L-cysteine to the nearest milligram onto a glassineweighing paper. Quantitatively transfer the contents of thepaper to a 1-L volumetric flask. Add approximately 800 mL ofwater. Add 2 mL
40、of nitric acid into the flask with a pipette.Swirl to dissolve the solids. Fill to the mark with water. TheL-cysteine solution stabilizes the ionic mercury and is used toprepare working standards.9.2 Mercuric Chloride Stock SolutionWeigh 0.0677 g ofmercuric chloride onto weighing paper. Quantitative
41、ly transferthe material to a 500 mL volumetric flask using the L-cysteinesolution prepared in accordance with 9.1. Fill to the mark withL-cysteine solution and mix. This results in a mercury concen-tration of 100 mg/kg.9.3 Working Standards SetPrepare a set of mercury stan-dards that are appropriate
42、 to the range settings on the instru-ment in use. An example of such a set follows.9.3.1 Witha5mLpipette, transfer an aliquot of themercuric chloride stock solution to a 100 mL volumetric flask.Fill the flask to the mark with L-cysteine solution and mix. Thismakes a 5 mg/kg standard.9.3.2 Witha1mLpi
43、pette, transfer an aliquot of themercuric chloride stock solution to a 100 mL volumetric flaskand fill up to the mark with L-cysteine solution. Mix. Thismakes a 1 mg/kg standard.9.3.3 Perform appropriate dilutions of the 1 mg/kg standardwith L-cysteine solution to prepare 0.1 and 0.01 mg/kgmercury s
44、tandards.10. Instrument Preparation10.1 Assemble the instrumental system in accordance withthe manufacturers instructions. Follow the instrument manu-facturers recommended procedure to optimize the perfor-mance of the instrument.10.2 Choose the proper sensitivity range and sample heatingmode based u
45、pon the expected mercury concentration and thesample matrix.10.3 Reagents used for the analysis of hydrocarbon samplesshould be placed in the 750C muffle furnace overnight prior touse. Sample boats should also be pretreated in the mufflefurnace before initial use.10.4 The instrument should be run th
46、rough several heatingcycles after being powered up to attain a new blank signal. Asatisfactory blank should have stable response and a signal thatcorresponds to the equivalent of 0.1 ng/g mercury in thesample.11. Calibration Procedure11.1 Choose the working standard to match the sensitivityrange to
47、which the instrument is set. For example, a sensitivityrange with a maximum of 2 ng of mercury would require usingthe nominal 0.01 mg/kg standard solution. A sensitivity rangeof 20 ng would use the 0.1 mg/kg standard and so on.11.2 After the instrument has cycled several times and astable response h
48、as been attained, initiate the analysis with nosample boat in the furnace and record the blank value.11.3 Using a micropipetter and tip, transfer 50 L ofstandard solution to a cooled sample boat. Place the sampleboat into the furnace area and start the instrument. Repeat thisstep for 100, 150, and 2
49、00 L aliquots to span the effectiverange of response. Create a calibration curve by assigning theappropriate mass of mercury introduced into the instrumentwith the corresponding response. Follow the manufacturersinstructions to use available software tools that automate thecalculations.11.4 A reagent blank is subtracted from the response of thesamples to compensate for trace mercury signal associated withthe sample boat and combustion reagents.11.4.1 Remove a sample boat and treated reagent(s) fromthe muffle furnace and allow to cool in a container that isp
