1、Designation: D7623 10 (Reapproved 2015)Standard 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 oforigina
2、l 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 procedures to determine thetotal mercu
3、ry content in a sample of crude oil.1.2 The test method may be applied to crude oil samplescontaining between 5 ng mL to 400 ng mL of mercury. Theresults may 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
4、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, orits vapor, may be hazardous to health and corrosive tomaterials. Caution should be taken when h
5、andling 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 should be aware that selling mercuryand/or mercury containing products into your state or count
6、rymay 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-priate safety and health practices and determine the applica-bility of regulatory limitations p
7、rior 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, PetroleumProducts, and LubricantsD4177 Practice for Automatic Sampling of Petroleum andPetroleum P
8、roductsD6299 Practice for 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
9、 in Petroleum Productsand 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. Terminolog
10、y3.1 For definitions of 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 700 C) and chemi-cally decomposed.
11、 The decomposition products are carried byflowing treated air to the catalytic section of the furnace (atabout 850 C), where oxidation is completed. The decomposi-tion products are carried to a gold amalgamator that selectivelytraps mercury. After the system is flushed with oxygen toremove any remai
12、ning decomposition products other thanmercury, the amalgamator is rapidly heated to about 600 C,releasing mercury vapor. Flowing oxygen carries the mercuryvapor through absorbance cells positioned in the light path ofsingle wavelength cold vapor atomic absorption spectropho-tometer. Absorbance peak
13、height or peak area, as a function ofmercury concentration, is measured at 253.65 m.NOTE 1Mercury and mercury salts can be volatized at low tempera-tures. Precautions against inadvertent mercury loss should be taken whenusing this test method.1This test method is under the jurisdiction of ASTM Commi
14、ttee D02 onPetroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility ofSubcommittee D02.03 on Elemental Analysis.Current edition approved April 1, 2015. Published June 2015. Originallyapproved in 2010. Last previous edition approved in 2010 as D7623 10.DOI:10.1520/D7623-10R15
15、.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 standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box
16、C700, West Conshohocken, PA 19428-2959. United States15. Significance and Use5.1 The emission of mercury during crude oil refining is anenvironmental concern. The emission of mercury may alsocontaminate refined products and form amalgams with metals,such as aluminum.5.2 When representative test port
17、ions are analyzed accord-ing to this procedure, the total mercury is representative ofconcentrations in the sample.6. Apparatus6.1 There are several configurations of the instrumentalcomponents that can be used satisfactorily for this testmethod.3Functionally, the instrument shall have the following
18、components: sample heating furnace, decomposition furnace,gold amalgamator, amalgamator furnace, measuring cuvettes,mercury lamp, and detector. The following requirements arespecified for all approved instruments.NOTE 2Approval of an instrument with respect to these functions isparamount to this tes
19、t method, since such approval tacitly providesapproval of both the materials and the procedures used with the system toprovide these functions.6.1.1 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
20、be operated at a temperature high enough tocompletely decompose the sample. The suggested operatingtemperature is at least 700 C.6.1.3 The catalyst shall be capable of completing the oxi-dation of the sample and trapping halogens as well as nitrogenand sulfur oxides. The suggested operating temperat
21、ure of thecatalytic tube is 850 C.6.1.4 The instrument shall contain one or more gold amal-gamator fixed to an inert material and shall be capable oftrapping 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 i
22、nstrument shall have an absorption cell throughwhich the elemental mercury released from the gold amalgam-ator flows. The cell shall be heated to avoid any condensationof water or other decomposition products.6.1.7 The light source for the atomic absorption processshall be a low pressure mercury lam
23、p.6.1.8 A narrow bandpass interference filter ormonochromator, capable of isolating the 253.65 nm mercuryline, shall be used.6.1.9 The system may contain a computer for controllingthe various operations of the apparatus, for recording data, andfor reporting results.6.2 Analytical Balance, with a sen
24、sitivity of 0.1 mg.6.3 Sample Combustion Boats, porcelain, quartz, or othermaterial as recommended and of convenient size suitable foruse in the instrument being used.6.4 Crucibles, porcelain, high-form, 40 mL capacity orsuitable size for heating reagent in furnace.6.5 Micropipettes, one or more uni
25、ts of variable volumes tocover a range of 10 L to 250 L. Appropriately sized tipsshould also be available.6.6 Ultrasonic HomogenizerA bath type ultrasonic ho-mogenizer is used to dissociate particulate mercury and thor-oughly mix the sample.6.7 Electric Muffle Furnace, capable of maintaining 750 C6
26、25 C and sufficiently large to accommodate the sampleboats and reagent containers.6.8 Glassware, class A, volumetric flasks and pipettes ofvarious capacities. All glassware must be thoroughly cleanedwith freshly prepared 10 % nitric acid solution and rinsed withwater. It is recommended that dedicate
27、d glassware be main-tained to minimize cross contamination.7. Sample7.1 Obtain the analysis sample of crude oil in accordancewith Practice D4057 or D4177. Crude oil should be collectedin a manner that ensures a representative sample from the bulkcontainer is obtained.7.2 To prevent loss of mercury d
28、uring storage and handlingof samples, follow Practice D7482. Sample should not becollected in 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 containe
29、rs should be kept tightly cappedand stored in a cool location free from direct sunlight.8. Reagents8.1 Purity 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
30、 of the American Chemical Society wheresuch specifications are available.4Other grades may be used,provided 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, reference
31、to water shall be understood to mean reagent water conformingto Type II of Specification D1193. Water must be checked forpotential mercury contamination before use.8.3 Air or OxygenFiltered, purified air or high purityoxygen, as specified by the instrument manufacturer, shall be3The sole source of s
32、upply 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 Headquarters. Your com-ments w
33、ill 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 the American Chemical Society, se
34、e 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 10 (2015)2used. The air must be mercury-free. Some instruments processincoming combustion air with filte
35、rs and driers before it is usedfor the analysis.8.4 Certified Reference Materials (CRMs)Use CertifiedReference Material (CRM) crude oils with mercury values forwhich confidence limits are issued by a recognized certifyingagency such as the National Institute of Standards and Tech-nology (NIST).8.4.1
36、 All CRMs, reference crude oils, or calibrating agentsmust 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.8.5 L-cysteine, 99+ % purity. Reagents must be evaluatedfor
37、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+ % purity. A commerciallyprepared mercury stock standard may be used.8.8 Phosphate Buffer, pH 7.2. Some phosphate buffers usemercury compo
38、unds as preservative. The buffer must bemercury-free. Check with the instrument manufacturer forsources of suitable buffer.8.9 Combustion Reagents:8.9.1 Additive 1 or B (Aluminum Oxide), ground, availablefrom instrument manufacturer.8.9.2 Additive 2 or M, 40/60 m % mixture of calciumhydroxide and so
39、dium 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 Weighing Paper.9. Preparation of Mercury Standards9.1 L-cysteine Solution, 0.001 m %Weigh approximately0.010 g of L-cysteine to the nearest
40、 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 of nitric acid into the flask with a pipette.Swirl to dissolve the solids. Fill to the mark with water. TheL-cysteine solution stabilizes t
41、he ionic mercury and is used toprepare working standards.9.2 Mercuric Chloride Stock SolutionWeigh 0.0677 g ofmercuric chloride onto weighing paper. Quantitatively transferthe material to a 500 mL volumetric flask using the L-cysteinesolution prepared in accordance with 9.1. Fill to the mark withL-c
42、ysteine 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 to the range settings on the instru-ment in use. An example of such a set follows.9.3.1 With a 5 mL pipette, transfer an aliquot of the me
43、rcu-ric chloride stock solution to a 100 mL volumetric flask. Fillthe flask to the mark with L-cysteine solution and mix. Thismakes a 5 mg kg standard.9.3.2 With a 1 mL pipette, transfer an aliquot of the mercu-ric chloride stock solution to a 100 mL volumetric flask and fillup to the mark with L-cy
44、steine solution. Mix. This makes a1 mg kg standard.9.3.3 Perform appropriate dilutions of the 1 mg kg standardwith L-cysteine solution to prepare 0.1 mg kg and 0.01 mg kgmercury standards.10. Instrument Preparation10.1 Assemble the instrumental system in accordance withthe manufacturers instructions
45、. 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 upon the expected mercury concentration and thesample matrix.10.3 Reagents used for the analysis of hydrocarbon samplessho
46、uld be placed in the 750 C muffle furnace overnight priorto use. Sample boats should also be pretreated in the mufflefurnace before initial use.10.4 The instrument should be run through several heatingcycles after being powered up to attain a new blank signal. Asatisfactory blank should have stable
47、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 which the instrument is set. For example, a sensitivityrange with a maximum of 2 ng of mercury would require usingthe no
48、minal 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 has been attained, initiate the analysis with nosample boat in the furnace and record the blank value.11.3 Using a microp
49、ipetter and tip, transfer 50 L of stan-dard solution to a cooled sample boat. Place the sample boatinto the furnace area and start the instrument. Repeat this stepfor 100 L, 150 L, and 200 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 com
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