1、Designation: E1479 99 (Reapproved 2011)E1479 16Standard Practice forDescribing and Specifying Inductively-Coupled InductivelyCoupled Plasma Atomic Emission Spectrometers1This standard is issued under the fixed designation E1479; the number immediately following the designation indicates the year ofo
2、riginal 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 practice describes the components of an inductively-cou
3、pled inductively coupled plasma atomic emission spectrometer(ICP-AES) that are basic to its operation and to the quality of its performance. This practice identifies critical factors affectingaccuracy, precision, and sensitivity. It is not the intent of this practice to specify component tolerances
4、or performance criteria,since these are unique for each instrument.Aprospective user should consult with the vendormanufacturer before placing an order,to design a testing protocol to demonstrate that demonstrates the instrument meets all anticipated needs.1.2 The values stated in SI units are to be
5、 regarded as standard. The values given in parentheses are for information only.1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and det
6、ermine the applicability of regulatorylimitations prior to use. Specific safety hazard statements are given in Section 13.2. Referenced Documents2.1 ASTM Standards:2E135 Terminology Relating to Analytical Chemistry for Metals, Ores, and Related MaterialsE158 Practice for Fundamental Calculations to
7、Convert Intensities into Concentrations in Optical Emission SpectrochemicalAnalysis (Withdrawn 2004)3E172 Practice for Describing and Specifying the Excitation Source in Emission Spectrochemical Analysis (Withdrawn 2001)3E416 Practice for Planning and Safe Operation of a Spectrochemical Laboratory (
8、Withdrawn 2005)3E520 Practice for Describing Photomultiplier Detectors in Emission and Absorption Spectrometry3. Terminology3.1 DefinitionsFor terminology relating to emission spectrometry, refer to Terminology E135.4. Summary of Practice4.1 An ICP-AES is an instrument used to determine elemental co
9、mposition. It typically is comprised of several assembliesincluding a radio-frequency (RF) generator, an impedance matching network (where required), an induction coil, a plasma torch,a plasma ignitor system, a sample introduction system, a light radiant energy gathering optic, an entrance slit and
10、dispersingelement to sample and isolate wavelengths of light emitted from the plasma, one or more devices for converting the emitted lightinto an electrical current or voltage, one or more analog preamplifiers, one or more analog-to-digital converter(s), and a dedicatedcomputer with printer (see Fig
11、. 14).4.1.1 The sample is introduced into a high-temperature (6000 K) plasma that is formed from the inductive energy transfer toand subsequent ionization of the gas stream contained in the torch. The torch is inserted through metal tubing formed into a helix,mounted centrally in a metal structure,
12、which is called the load coil. Energy is applied to the load coil by means of an RF generator.1 This practice is under the jurisdiction of ASTM Committee E01 on Analytical Chemistry for Metals, Ores, and Related Materials and is the direct responsibility ofSubcommittee E01.20 on Fundamental Practice
13、s.Current edition approved Nov. 15, 2011Nov. 1, 2016. Published June 2012December 2016. Originally approved in 1992. Last previous edition approved in 20052011 asE1479 99 (2005).(2011). DOI: 10.1520/E1479-99R11.10.1520/E1479-16.2 For referencedASTM standards, visit theASTM website, www.astm.org, or
14、contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3 The last approved version of this historical standard is referenced on www.astm.org.4 Courtesy of PerkinElmer, Inc., 761 Main Ave.,
15、 Norwalk, CT 06859.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that user
16、s consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States14.1.2 The term inductively-co
17、upled inductively coupled refers to the fact that the physical phenomenon of induction creates aplasma by transferring energy from the load coil to the gas stream that has been momentarily preionized by a high voltage ignitorelectrodespark that functions only during plasma ignition.4.2 When material
18、 passes through the plasma, it is vaporized, atomized, and many elements are almost completely ionized.partly ionized. The produced atoms and ions are excited into an energetically higher state. Free atoms and ions are excited bycollision from their ground states. When the states mainly by collision
19、 with the major plasma constituents. The excited atoms orions subsequently decay to a lower energy state, theystate and emit photons, some of which pass through the entrance slit of aspectrometer. Each element emits a unique set of emission lines. Photons of a desired wavelength may be selected from
20、 theultraviolet and visible spectra by means of a dispersing element.4.2.1 Instruments may determine elements either simultaneously or sequentially. The output of the detector generally is directedto a preamplifier, an analog-to-digital converter, and a computer which measures and stores a value pro
21、portional to the electricalcurrent or voltage generated by the detector(s). Using blank and known calibration solutions, a calibration curve is generated foreach element of interest.4.2.2 The computer compares the signals arising from the various elements in the sample to the appropriate calibration
22、 curve.The concentrations of more than 70 elements may be determined.4.3 Sensitivities (see 12.3) in a simple aqueous solution are less than one part per million (ppm) 1 g/g for all of these elements,generally less than 10 parts per billion (ppb) ng/g for most, and may even be below 1 ppbng/g for so
23、me.4.3.1 Organic liquids may also be used as solvents with many yielding sensitivities that are within an order of magnitude ofaqueous limits for many common organic solvents. limits. Some organic solvents may afford detection limits similar or evensuperior to those obtained using aqueous solutions.
24、4.3.2 Direct sampling of solid materials has been performed successfully by such techniques as spark or laser ablation andablation, by electrothermal vaporization and by slurry nebulization. However, these require greater care in the choice of referencematerials and the operation of the sampling dev
25、ices. Solid materials, therefore,Therefore, solid materials are usually dissolved priorto analysis.5. Significance and Use5.1 This practice describes the essential components of an inductively-coupled plasma atomic emission spectrometer(ICP-AES). ICP-AES.The components include excitation/radio-frequ
26、ency generators, sample introduction systems, spectrometers,detectors, and signal processing and displays. This description allows the user or potential user to gain a cursory understandingof an ICP-AES system.This practice also provides a means for comparing and evaluating various systems, as well
27、as understandingthe capabilities and limitations of each instrument.FIG. 1 Components of Inductively Coupled PlasmaICP-AES4E1479 1625.2 TrainingThe vendormanufacturer should provide training in safety, basic theory of ICP spectrochemical ICP-AESanalysis, operations of hardware and software, and rout
28、ine maintenance for at least one operator. Training ideally should consistof the basic operation of the instrument at the time of installation, followed by an in-depth course one or two months later.Advanced courses are also offered at several of the important spectroscopy meetings that occur throug
29、hout the year as well as byindependent training institutes. Furthermore, several Several independent consultants are available who can provide training, inmost cases sometimes at the users site.6. Excitation/Radio Frequency Generators6.1 ExcitationA specimen is converted into an aerosol entrained in
30、 a stream of argon gas and transported through a hightemperature plasma. The plasma produces excited neutral atoms and excited ions. The photons emitted when excited atoms or ionsreturn to their ground states or lower energy levels are measured and compared to emissions from reference materials of s
31、imilarcomposition. For further details see Practice E172.6.2 Radio-Frequency Generator:6.2.1 An RF generator is used to initiate and sustain the argon plasma. Commercial generators operate at 27.12 andor 40.68MHz since these frequencies are designated as clear frequencies by U.S. Federal Communicati
32、ons CommitteeCommission (FCC)regulations. Generators typically are capable of producing 1.0 kW to 2.0 kW for the 27.12 MHz generator and 1.0 kW to 2.3 kWfor the 40.68 MHz system.generator.6.2.2 Generators more powerful than 2.5 kW are of limited practical analytical utility and are not commercially
33、marketed withICP spectrometers. The power requirements are related to torch geometry and types of samples to be analyzed. Refer to PracticeE172 for details. More power (typically 1.5 kW to 2 kW for a 27.12 MHz systemgenerator utilizing a 20-mm outside diametertorch and 1.2 kW to 1.7 kW for a 40.68 M
34、Hz generator) is required for analyzing samples dissolved in organic solvents than isneeded for aqueous solutions (approximately 1.0 kW to 1.4 kW). Less power is required for small diameter torches (for example,650 W to 750 W for a 13-mm outside diameter torch).6.3 Load Coil:6.3.1 A coil made from c
35、opper (or another metal or an alloy with similar electrical properties) is used to transmit transmitspower from the generator to the plasma torch (see 7.6). A typical design consists of a two- to six-turn coil of about 1-in. (25-mm)diameter, made from 18-in. (3-mm) outside diameter and 116-in. (1.6-
36、mm) inside diameter copper tubing (though larger tubing isused with two-turn coils). The tubing is fitted with ferrules or similar devices to provide a leak-free connection to a coolant, eitherrecirculated by a pump or fed from a municipal water supply. Argon gas blown through the coil has been used
37、 to cool other loadcoils.Modern instruments also utilize air convection/radiation-cooled solid load coils, completely avoiding leak risks from liquidcooling.6.3.2 The Especially for liquid-cooled load coils, the high power conducted by the coil can lead to rapid oxidation, surface metalvaporization,
38、 RF arc-over and even melting if the coil is not cooled continuously.6.3.3 A safety interlock must be included to turn off the RF generator in case of loss of coolant flow.cooling.6.4 Impedance Matching:6.4.1 To optimize power transfer from the generator to the induced plasma, the output impedance o
39、f the generator must bematched to the input impedance of the load coil. Some instruments include an operator-adjustable capacitor for impedancematching.6.4.2 Alternately, RF frequency may be automatically tuned or varied in free-running fashion against a fixed capacitor-inductornetwork. Most modern
40、instruments, however, incorporate However, most modern instruments incorporate either an automaticimpedance matching network or a self-adjusting free running RF generator to simplify ignition, to reduce incidence of plasmaextinction when introducing sample solutions, and to optimize power transfer.F
41、IG. 2 Concentric Glass Nebulizer (CGN)4E1479 1637. Sample Introduction7.1 The sample introduction system of an ICP instrument consists of a nebulizer, a spray chamber, and a torch.7.2 Nebulizers:7.2.1 Samples generally are presented to the instrument as aqueous or organic solutions.Anebulizer is emp
42、loyed to convert thesolution to an aerosol suitable for transport into the plasma where vaporization, atomization, excitation, and emission occur.7.2.2 Some nebulizers, designated as self-aspirating pneumatic nebulizers, operating on the Venturi principle, create a partialvacuum to force liquid up a
43、 capillary tube into the nebulizer. Precision of operation may be improved if a peristaltic pump controlsthe solution flow rate.7.2.3 Other nebulizers require an auxiliary device, such as a peristaltic pump, to drive solution to the nebulizer. Generally,pump-fed nebulizers are more tolerant of high
44、levels of dissolved solids and much less affected by suspended solids and viscosityvariations.7.2.4 If fluoride is present in solutions to be analyzed, it is necessary to employ a nebulizer fabricated from hydrofluoric acid(HF)-resistant HF-resistant materials (see 7.4.1.). It is possible to use the
45、 HF-resistant nebulizer for most other types of solutions,but sensitivity and precision may be degraded.An HF-resistant nebulizer may be more expensive to acquire and repair, and requiregreater operator proficiency and training than other nebulizers.7.3 Self-Aspirating or Non-Pump-Fed Nebulizers:7.3
46、.1 Concentric Glass Nebulizers (CGN):7.3.1.1 CGNs consist of a fine capillary through which the sample solution flows surrounded by a larger tube drawn to a fineorifice (concentric) slightly beyond the end of the central capillary (see Fig. 2). Minor variations in capillary diameter andplacement aff
47、ect optimal operating pressure for the sample gas flow and change the sample solution uptake rate. Uptake rates ofliquid are typically 0.5 mL/min to 3 mL/min.7.3.1.2 CGNs exhibit somewhat degraded sensitivity and precision for solutions that approach saturation or concentrations ofmore thatthan a fe
48、w tenths of a percent of dissolved solids. This problem can be greatly reduced by using an inner argon streamthat has been bubbled through water in order to humidify the sample gas argon. Furthermore, since suspended solids may clog thetip, it is desirable to include a piece of capillary tubing of e
49、ven smaller diameter in the sample solution uptake line. This actionwill isolate a potential clogging problem prior to clogging at the nebulizer tip.7.3.2 Micro-Concentric Nebulizer (MCN):7.3.2.1 To some extent, the MCN mimics the concept and function of the CGN but the MCN employs a thinner-walledpoly-ether-imide capillary and TFE-fluorocarbon (or other polymer) outer body to minimize or eliminate undesirable large dropformation and facilitate HF tolerance (see Fig. 34,5).Atrue aerosol, as opposed to a mist, is produced consisting of only the desiredsmallest size dropl
