1、Designation: D7622 101Standard 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 ofor
2、iginal 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.1NOTEAdded missing “C” variable throughout editorially in November 2010.1
3、. Scope1.1 This test method covers the procedure to determine thetotal mercury 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 contai
4、ningbetween 5.0 to 350 ng/mL of mercury. The results may beconverted to mass 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 tha
5、t 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 andmercury containing products. See the applicable product Ma-terial Safety Data Sheet (MSDS) for details and EPAswebs
6、itehttp:/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 law.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. I
7、t 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. Referenced Documents2.1 ASTM Standards:2D1193 Specification for Reagent WaterD4057 Practice for Manual Sampling of Petr
8、oleum andPetroleum ProductsD4175 Terminology Relating to Petroleum, PetroleumProducts, and LubricantsD4177 Practice for Automatic Sampling of Petroleum andPetroleum ProductsD6299 Practice for Applying Statistical Quality Assuranceand Control Charting Techniques to Evaluate AnalyticalMeasurement Syst
9、em PerformanceD6300 Practice for Determination of Precision and BiasData 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
10、 AnalysisD7623 Test Method for Total Mercury in Crude Oil UsingCombustion-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 decomposi
11、tion ofthe analysis sample in air is used to liberate mercury. Thesample 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 evap
12、o-rated and partially dissociated forming elemental mercuryvapor. Mercury 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
13、totally dissociated, and the organic matrix of the sample isburnt out. Continuously flowing air carries mercury and othercombustion products through absorbance analytical cell heated1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direc
14、t 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, refer
15、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.up to 750C positioned in the light path of double-wave coldvapor Zeeman atomic absorption spectrophotometer. The mer-cury reson
16、ance line 253.65 nm is split to several components,one of those falling within 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
17、. Absorbance peak area or peak height is afunction of the mercury concentration.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 cru
18、de 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 portions are analyzed accord-ing to this procedure, the total mercury is representative ofconcentrations in the sample.
19、6. Apparatus6.1 General configuration of the instrument shall have thefollowing 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
20、, anddetector. The following requirements are specified for allapproved instruments.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 toprovi
21、de these functions.6.1.1 Zeeman Mercury SpectrometerAtomic absorptionspectrometer 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 complet
22、elydecompose the sample. The suggested operating temperature isat least 600C.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 le
23、ast 700C.6.1.4 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 sensitivity of 0.1 mg.6.3 Sample Boats, quartz, stainless steel, porcelain, or othermaterial as recommended and conveni
24、ent size suitable for usein the instrument being used.6.4 Micropipetters, 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 part
25、iculate mercury and thor-oughly mix the sample.6.6 Glassware, volumetric 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
26、be maintained 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 of the bulk containeris obtained.7.2 To prevent loss of mercury during storage and hand
27、lingof samples, follow Practice D7482. Samples 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 containers should be kept tig
28、htly cappedand stored in a cool location.8. Reagents and Materials8.1 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 of the American Chemical Society
29、 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, referenceto water shall be understood to m
30、ean reagent water conformingto Type II of Specification D1193. Water must be checked forpotential mercury contamination before use.8.3 A standard sample of mercury ions solution (concentra-tion C1= 1.0 g/L).8.4 Certified Reference Materials (CRMs)Use CertifiedReference Material (CRM) crude oils with
31、 mercury values forwhich confidence limits are issued by a recognized certifyingagency such as the National Institute of Standards and Tech-nology (NIST).8.5 Nitric Acid, concentrated, Trace Metal Grade or better.3The sole source of supply of the apparatus known to the committee at this timeis Lumex
32、 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. Your com-ments will receive careful consideration at a meeting of the responsible technicalc
33、ommittee,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 Chemical Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., a
34、nd the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.D7622 10128.6 Combustion Reagents, activated charcoal, 30 3 50mesh.8.7 Potassium Dichromate Solution, 4 % (mass)Place a4 g portion of potassium dichromate in a volumetric flask(volume of
35、 100 mL), dissolve in distilled water and dilute withthe distilled water up 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 careful
36、ly 50 mL ofconcentrated nitric acid (d = 1.37 g/mL). Stir constantly whilepouring 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 w
37、ith a plug stopper.Storage time is 3 months.8.9 All CRMs, reference crude oils, 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. Preparati
38、on of Standards9.1 Working Standard SetPrepare a set of standards thatare appropriate 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 NIS
39、T or other standard reference materialissuing bodies traceable standard solution (concentration C1=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 (C2). The solution maybe stored in a
40、 refrigerator during 6 months.9.1.2 Place 30 mL of a dilution solution in a volumetricflask (100 mLvolume). Then place 10 mLof a standard sampleof mercury solution C2= 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/
41、L (C3). Thesolution may be stored in a refrigerator during 3 months.9.1.3 Place 30 mL of a dilution solution in a volumetricflask (100 mLvolume). Then place 10 mLof a standard sampleof mercury solution C3= 2.0 mg/L. Bring the contents of theretort up to the mark with the dilution solution and stirth
42、oroughly. This makes a 200 g/L (C4). The solution may bestored in a refrigerator during 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 solution C4= 200 g/L.) Bring the contents of theretort up to the mark with the
43、 dilution solution and stirthoroughly. This makes a 20 g/L (C5). The solution may bestored 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
44、 accordance with the manufacturers instructions.Follow the instrument manufacturers recommended 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
45、also be pretreatedin the muffle furnace before initial use.10.4 A satisfactory blank should 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 micropi
46、petter and tip, transfer100 L of the dilution solution on to a charcoal media. Placethe sample 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 a
47、nd tip, transfer100 L of standard solution 200 g/L on to a charcoal media.Place the sample 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 introduce
48、d into theinstrument with the corresponding response. Follow manufac-turers recommendations 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 obt
49、ained for thecontrol sample must be within established limits. If a controlcheck sample result 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 su
