1、Designation: D 7260 06Standard Practice forOptimization, Calibration, and Validation of InductivelyCoupled Plasma-Atomic Emission Spectrometry (ICP-AES)for Elemental Analysis of Petroleum Products andLubricants1This standard is issued under the fixed designation D 7260; the number immediately follow
2、ing the designation indicates the year oforiginal adoption or, in the 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. Scope1.1 This practice cov
3、ers information on the calibration andoperational guidance for the multi-element measurements us-ing inductively coupled plasma-atomic emission spectrometry(ICP-AES).1.2 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of t
4、he 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:2D 4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD 4307 Practice for Preparation of L
5、iquid Blends for Use asAnalytical StandardsD 6299 Practice for Applying Statistical Quality AssuranceTechniques to Evaluate Analytical Measurement SystemPerformanceD 6792 Guide for Quality System in Petroleum Productsand Lubricants Testing Laboratories2.2 ICP-AES Related Standards:C 1111 Test Method
6、 for Determining Elements in WasteStreams by Inductively Coupled Plasma-Atomic EmissionSpectroscopyC 1109 Practice for Analysis of Aqueous Leachates fromNuclear Waste Materials Using Inductively CoupledPlasma-Atomic Emission SpectroscopyD 1976 Test Method for Elements in Water by Inductively-Coupled
7、 Argon Plasma Atomic Emission SpectroscopyD 4951 Test Method for Determination of Additive Ele-ments in Lubricating Oils by Inductively Coupled PlasmaAtomic Emission SpectrometryD 5184 Test Methods for Determination of Aluminum andSilicon in Fuel Oils by Ashing, Fusion, InductivelyCoupled Plasma Ato
8、mic Emission Spectrometry, andAtomic Absorption SpectrometryD 5185 Test Method for Determination of Additive Ele-ments, Wear Metals, and Contaminants in Used Lubricat-ing Oils and Determination of Selected Elements in BaseOils by Inductively Coupled Plasma Atomic EmissionSpectrometry (ICP-AES)D 5600
9、 Test Method for Trace Metals in Petroleum Coke byInductively Coupled Plasma Atomic Emission Spectrom-etry (ICP-AES)D 5708 Test Methods for Determination of Nickel, Vana-dium, and Iron in Crude Oils and Residual Fuels byInductively Coupled Plasma (ICP) Atomic Emission Spec-trometryD 6130 Test Method
10、 for Determination of Silicon and OtherElements in Engine Coolant by Inductively CoupledPlasma-Atomic Emission SpectroscopyD 6349 Test Method for Determination of Major and MinorElements in Coal, Coke, and Solid Residues from Com-bustion of Coal and Coke by Inductively CoupledPlasmaAtomic Emission S
11、pectrometryD 6357 Test Methods for Determination of Trace Elementsin Coal, Coke, and Combustion Residues from CoalUtilization Processes by Inductively Coupled PlasmaAtomic Emission Spectrometry, Inductively CoupledPlasma Mass Spectrometry, and Graphite Furnace AtomicAbsorption SpectrometryD 7040 Tes
12、t Method for Determination of Low Levels ofPhosphorus in ILSAC GF 4 and Similar Grade Engine Oilsby Inductively Coupled Plasma Atomic Emission Spec-trometry1This practice is under the jurisdiction of ASTM Committee D02 on PetroleumProducts and Lubricants and is the direct responsibility of Subcommit
13、tee D02.03 onElemental Analysis.Current edition approved May 1, 2006. Published June 2006.2For 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 Sum
14、mary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.D 7111 Test Method for Determination of Trace Elements inMiddle Distillate Fuels by Inductively Coupled PlasmaAtomic Emission Spectrometry (ICP-AES)E 1479 P
15、ractice for Describing and Specifying Inductively-Coupled Plasma Atomic Emission Spectrometers2.3 Other Standards:IP 437 Determination of Additive Elements in UnusedLubricating Oils and Additive Packages by InductivelyCoupled Plasma-Atomic Emission SpectrometryISO/TC 17/SC 1 N 883 Guidelines for the
16、 Preparation ofStandard Methods of Analysis Using Inductively CoupledPlasma-Atomic Emission Spectrometry and for Use ofICP Spectrometry for the Determination of ChemicalComposition (1991)3. Summary of Practice3.1 An Inductively Coupled Plasma-Atomic Emission Spec-trometry (ICP-AES) instrument is one
17、 that is used to determineelemental composition of various liquid matrices. Details ofthe instrument components are given in Practice E 1479. Thispractice summarizes the protocols to be followed duringcalibration and verification of the instrument performance.4. Significance and Use4.1 Accurate elem
18、ental analysis of petroleum products andlubricants is necessary for the determination of chemicalproperties, which are used to establish compliance with com-mercial and regulatory specifications.4.2 Inductively Coupled Plasma-Atomic Emission Spec-trometry is one of the more widely used analytical te
19、chniquesin the oil industry for multi-element analysis as evident from atleast twelve standard test methods (for example, Test MethodsC 111, D 1976, D 4951, D 5184, D 5185, D 5600, D 5708,D 6130, D 6349, D 6357, D 7040, and D 7111) published forthe analysis of fossil fuels and related materials. The
20、se havebeen briefly summarized by Nadkarni.34.3 The advantages of using an ICP-AES analysis includehigh sensitivity for many elements of interest in the oilindustry, relative freedom from interferences, linear calibrationover a wide dynamic concentration range, single or multi-element capability, an
21、d ability to calibrate the instrument basedon elemental standards irrespective of their elemental chemicalforms, within limits described below such as solubility andvolatility assuming direct liquid aspiration. Thus, the techniquehas become a method of choice in most of the oil industrylaboratories
22、for metal analyses of petroleum products andlubricants.5. Apparatus5.1 SpectrometerAn inductively coupled plasma emissionspectrometer with a spectral bandpass of 0.05 nm or less isrequired. The spectrometer may be of the simultaneous multi-elemental or sequential scanning type. The spectrometer mayb
23、e of the air path, inert gas path, or vacuum type, with spectrallines selected appropriately for use with specific instrument.Either an analog or digital readout system may be used.5.2 An ICP-AES instrument system is typically comprisedof several assemblies including a radio-frequency (RF) gen-erato
24、r, an impedance matching network (where required), aninduction coil, a plasma torch, a plasma igniter system, asample introduction system, a light gathering optic, an entranceslit and dispersing element to separate and measure theintensity of the wavelengths of light emitted from the plasma,one or m
25、ore devices for converting the emitted light into anelectrical current or voltage, one or more analog preamplifiers,one or more analog-to-digital converter(s), and a dedicatedcomputer with printer. Solid state CCD or CID detectors ifused may not require extra analog-to-digital components.Recently mo
26、dern camera-type instruments have been supplant-ing the photomultiplier tube type detectors. Cameras may nothave high resolution, but they offer greater wavelength choice.5.2.1 Plasma can be monitored either axially versus radially.Potential for improved sensitivity as much as tenfold is oftenrealiz
27、ed with axial monitoring. However, the increased inter-ference from molecular background may compromise thesegains depending on the wavelength monitored and matrix used(especially for organics versus aqueous).5.2.2 Echelle SpectrometersMore recently echelle grat-ings are being increasingly used in s
28、everal commercial plasmaspectrometers. A prism is used as an order-sorter to improvesensitivity. To measure widely separated lines with usefulefficiency, echelle instruments have to be operated in manydifferent orders. This involves complex wavelength scanningprograms for computer controlled echelle
29、 monochromators.While the resolution of a grating monochromator is relativelyconstant across its working range, practical resolution of anechelle monochromator can vary considerably with wave-length. Inherently higher theoretical resolving power of theechelle when used in high order, relative to the
30、 diffractiongrating used in the first order, allows a relatively compactechelle instrument to achieve high resolving power. Thedetection limits obtained with echelle plasma spectrometers arecomparable to those achieved by grating spectrometers.5.3 Spectrometer Environment:5.3.1 Temperature fluctuati
31、ons affect the instrument stabil-ity. Some manufacturers provide systems for maintaining aconstant internal temperature within the optical compartmentand sample introduction area that assumes changes in theoutside temperature are not being controlled within the neces-sary specified range and rate of
32、 change to insure stability. Othermanufacturers design their spectrometers to be stable over aspecified temperature range without attempting to control thespectrometers internal temperature.5.3.2 Since temperature and humidity changes may alsoaffect the sample introduction system, detectors, and ele
33、ctronicreadout as well as the spectrometer alignment, some manufac-turers specify that care be used in selecting a location for thespectrometer that experiences minimal variation in temperatureand relative humidity. The user needs to provide a controlledenvironment as specified by the manufacturer.
34、This is a veryimportant factor in optimum performance of an ICP-AESsystem.3Nadkarni, R. A., “Use of ICP-AES for Metal Analysis in the Oil Industry,” ICPInformation Newsletter, Vol 30(10), 2005, pp. 10591061.D72600625.3.3 The generator output power and the plasma gas flowdetermine the plasma temperat
35、ure and thus significantly influ-ence the emission signal and the background. Thus, the powerapplied and gas flow adjustments may be used to control thesignal to background ratio and, matrix, and some spectralinterferences.5.4 Optical Path:5.4.1 Since oxygen exhibits increasing absorbance withdecrea
36、sing wavelengths below 200 nm, the performance of anair path instrument degrades below that wavelength and isgenerally not useful below approximately 190 nm.5.4.2 Purging the optical path with nitrogen or argon, oranother gas with low absorption in this ultraviolet region mayextend the spectral regi
37、on to wavelengths below 167 nm. Useof these purge gases is in general less expensive to maintainthan the vacuum path systems. Sealed optics filled with an inertgas is also available for such work.5.5 Wavelength Selection:5.5.1 When selecting the fixed position wavelengths to beutilized in a Paschen-
38、Runge polychromator for particularapplications, close collaboration between user and instrumentmanufacturer is critical. Camera instruments do not have thisproblem.5.5.2 If possible, use the peak and background wavelengthssuggested in the methods. When there is a choice such as withthe sequential in
39、struments, choose the wavelength that willyield signals of 100 to 10003 the detection limit sought. Also,ensure that the chosen wavelength will not be interfered withfrom unexpected elements. See Section 6.5.5.3 Often ion lines may be chosen for use over atom linesto avoid interelement interference
40、and sensitivity of detection.This choice will be dependent on the analyte of interest and thesample matrix being analyzed.5.6 Peristaltic PumpDifferences in the viscosities of thetest specimen solutions and standard solutions can causedifferences in the uptake rates adversely affecting the accuracyo
41、f the analysis. These effects can be minimized by using aperistaltic pump (or an internal standard). If a peristaltic pumpis used, inspect the pump tubing and replace it, if necessary,before starting each day. Verify the solution uptake rate dailyand adjust to the desired rate. Compatibility of the
42、solutionwith the peristaltic pump tubing must also be confirmed toprevent premature pump failure. A variety of polymeric mate-rial options are available for pump tubing to address thisconcern by simple empirical testing with the given solvent/sample matrix used. Generally speaking, the selected tubi
43、ngsoaked overnight in the solvent/sample matrix should notsoften, crack, or embrittle the tubing.5.7 Depending on the nebulizer design, starving solventflow (that is, flow below natural free aspiration rates) can havean effect on aerosol generation. Consistent flow can helpachieve enhanced analyte s
44、ensitivity.5.8 TorchInspect the torches before use for cracks anddiscarded or repaired as appropriate. Clean torches that are freeof carbon buildup should be used. The load coil should bereplaced or cleaned if oxidation or leaking of coolant isobserved. The glass also can devitrify especially at the
45、 aerosoltip with oxygen injection.5.9 SafetyThe ICP-AES instrument is not normally con-sidered as a hazardous instrument. However, appropriate pre-cautions should be taken regarding the fumes, heat, andUV/visible light radiation as well as appropriate RF shielding.The equipment should always be used
46、 according to themanufacturers operating instructions. No attempt should bemade to bypass the interlocks. Adequate cooling times must beallowed before handling any hot components. Any safetycovers must be in position.5.9.1 Fumes from the plasma and any ozone generated bythe UV radiation must be remo
47、ved by means of a suitable heatand acid resistant (acids can be formed from halogens orsulfate and nitrates in the solution) chimney fitted with anexhaust fan of sufficient capacity.5.9.2 A UV/visible light absorbing viewing window (withRF shielding) must always be in place to protect the eyes andsk
48、in of the operator from radiation.5.9.3 Often the organic samples and solvents used in or-ganic ICP-AES analysis are toxic and hazardous. All appropri-ate precautions must be taken in handling such materials toprotect the operators. Consult MSDS and other safety infor-mation before handling these ch
49、emicals.6. Interferences6.1 Several types of interference effects may contribute toinaccuracies in the elemental determination using ICP-AES.Principally these interferences can be classifies as spectral,physical, and chemical.6.2 Spectral Interferences:NOTE 1An empirical method for correcting spectral interferences isdetailed in Test Method D 5185.6.2.1 Spectral interferences can be categorized as (1) unre-solved overlap of a spectral line from another element, (2)unresolved overlap of molecular band spectra, (3) backgroundcontribution from continuous or recombination phenomen
