1、Designation: D6071 13Standard Test Method forLow Level Sodium in High Purity Water by Graphite FurnaceAtomic Absorption Spectroscopy1This standard is issued under the fixed designation D6071; the number immediately following the designation indicates the year oforiginal adoption or, in the case of r
2、evision, 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. Scope*1.1 This test method covers the determination of tracesodium in high purity water. The method range
3、of concentra-tion is 1 to 40 g/L sodium. The analyst may extend the rangeonce its applicability has been ascertained.NOTE 1It is necessary to perform replicate analysis and take anaverage to accurately determine values at the lower end of the statedrange.1.2 This test method is a graphite furnace at
4、omic absorptionspectrophotometric method for the determination of tracesodium impurities in ultra high purity water.1.3 This test method has been used successfully with a highpurity water matrix.2It is the responsibility of the analyst todetermine the suitability of the test method for other matrice
5、s.1.4 The values stated in SI units are to be regarded asstandard.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 app
6、lica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:D1066 Practice for Sampling SteamD1129 Terminology Relating to WaterD1192 Guide for Equipment for Sampling Water and Steamin Closed Conduits (Withdrawn 2003)3D1193 Specification for Reagent WaterD2777 Practi
7、ce for Determination of Precision and Bias ofApplicable Test Methods of Committee D19 on WaterD3370 Practices for Sampling Water from Closed ConduitsD3919 Practice for Measuring Trace Elements in Water byGraphite Furnace Atomic Absorption SpectrophotometryD4453 Practice for Handling of High Purity W
8、ater SamplesD5810 Guide for Spiking into Aqueous SamplesD5847 Practice for Writing Quality Control Specificationsfor Standard Test Methods for Water Analysis3. Terminology3.1 Definitions:3.1.1 For definitions of terms used in this test method, referto Terminology D1129.4. Summary of Test Method4.1 S
9、odium is determined by atomic absorption utilizing agraphite furnace for sample atomization.4.2 Asample volume of several microlitres, depending uponthe concentration of the analyte, is deposited on a graphite tubehoused within an electrical furnace, and the system is heated inan inert gas environme
10、nt. The sample is evaporated to dryness,ashed (charred or pyrolyzed), and atomized.4.3 Ground-state atoms are produced during the atomizationstage of the temperature program. The ground-state atomsabsorb the energy at a specific wavelength produced from asource as they are bombarded by the energy. T
11、he amount ofenergy absorbed is proportional to the concentration of theanalyte in the sample.4.4 The absorption signal produced during atomization isrecorded on a chart recorder or stored in microprocessormemory and compared to those standards taken through thesame process by means of an analytical
12、curve.4.5 A general guide for graphite furnace applications isgiven in Practice D3919.5. Significance and Use5.1 Small quantities of sodium, 1 to 10 g/L, can besignificant in high pressure boiler systems and in nuclear powersystems. Steam condensate from such systems must have lessthan 10 g/L. In ad
13、dition, condensate polishing system efflu-ents should have less than 1 g/L. Graphite furnace atomic1This test method is under the jurisdiction of ASTM Committee D19 on Waterand is the direct responsibility of Subcommittee D19.03 on Sampling Water andWater-Formed Deposits, Analysis of Water for Power
14、 Generation and Process Use,On-Line Water Analysis, and Surveillance of Water.Current edition approved Jan. 1, 2013. Published February 2013. Originallyapproved in 1996. Last previous edition approved in 2006 as D6071 06. DOI:10.1520/D6071-13.2RP2712 Sub ProgramGrab Sample Method Validation Report R
15、esults,Electric Power Research Institute, Palo Alto, CA 1987.3The last approved version of this historical standard is referenced onwww.astm.org.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19
16、428-2959. United States1absorption spectroscopy (GFAAS) represents technique fordetermining low concentrations of sodium.6. Interferences6.1 No known interferences from other constituents arefound in high purity waters.6.2 For a complete discussion on interferences with graphitefurnace procedures, r
17、efer to Practice D3919.6.3 Sodium is a common contaminant in many reagents.The analyst must ensure that the quality of the reagent used inthe procedure is sufficiently high to determine trace levels ofsodium.6.4 All plasticware and apparatus must be cleaned andmaintained to eliminate high background
18、 levels of sodiumwhen determining trace levels.6.5 Airborne particulates are a potential interference withthe analysis of sodium by GFAAS. The user must ensure thatall plasticware and other equipment is capped or stored in airtight containers.7. Apparatus7.1 Atomic Absorption Spectrophotometer , wit
19、h the capa-bility of setting the following instrumental parameters:Metal Wavelength, nm Slit width (SBW), nmSodium 589.0 0.5NOTE 2The manufacturers instructions should be followed for allinstrument parameters.7.2 Hollow Cathode Lamp, for sodium.7.2.1 Multielement hollow cathode lamps may be used ift
20、he analyst ensures the necessary sensitivity is available for thelow level determination.7.3 Graphite Furnace, capable of reaching temperaturessufficient to atomize the elements of interest. Maximumsensitivity will be obtained when atomization temperatures arereached rapidly.7.4 Graphite Tubes, comp
21、atible with the furnace device.Standard graphite tubes of uncoated graphite should be used.When maximum sensitivity is required, the analyst may chooseto use pyrolytically coated graphite tubes.7.5 Autosampler, compatible with the graphite furnace de-vice may be used to increase the precision of the
22、 injection ordispensing the sample into the graphite tube.7.6 Pipets, microlitre with disposable plastic tips. Sizes mayvary from 1 to 100 L, as required.7.7 Flasks, plastic, volumetric. Sizes may vary from 100 to1000 mL.7.8 Strip Chart Recorder (Computing Device withDisplay)The user must keep a per
23、manent record of the datain addition to instrument problems (drift, incompleteatomization, changes in sensitivity, etc.).7.8.1 The strip chart recorder with a response of 0.2 s or lessfor full scale deflection is recommended to ensure accuracy.8. Reagents and Materials8.1 Purity of ReagentsReagent g
24、rade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specifications of the Commit-tee onAnalytical Reagents of theAmerican Chemical Society.4Other grades may be used, provided it is first ascertained thatthe reagent is of sufficie
25、ntly high purity to permit its usewithout lessening the accuracy of the determination.8.2 Purity of WaterReference to water that is used forreagent preparation, rinsing or dilution shall be understood tomean water that conforms to the quantitative specifications ofType I reagent water of Specificati
26、on D1193.8.3 Sodium Solution, stock (1 mL = 1000 g Na)Dissolve2.542 g of sodium chloride in water and dilute to 1 L.8.4 Sodium Solution, intermediate (1 mL = 10.0 g Na)Dilute 10.0 mL of stock sodium solution from 8.3 to 1 L withwater.8.5 Sodium Solution, standard (1 mL = 0.05 g Na)Dilute5 mL of inte
27、rmediate sodium solution from 8.4 to 1 L withwater.NOTE 3Alternatively, the analyst may purchase a commerciallyavailable standard (1 mL = 1000 g Na). Additional dilution will benecessary to obtain the stock sodium solution concentration in 8.3.8.6 Argon, 99.99 % pure.9. Sampling9.1 Collect the sampl
28、e in accordance with Practices D1066and D3370 or Specification D1192.9.2 Samples should be collected in polystyrene, TFE-fluorocarbon or polypropylene bottles only. Do not use glass orpolyethylene containers. The containers should be rinsed withType I water. The container should be stored prior to u
29、se byeither air drying and capping or filling with Type I water andcapping. For further details, see Practice D4453.9.3 To avoid the possibility of contamination, samplesshould not be acidified.10. Calibration10.1 Prepare standards for the analytical calibration contain-ing 0.0, 1.0, 5.0, 10.0, and
30、25.0 g/LNa by diluting 0, 2, 10, 20,and 50 mL sodium standard solution in 8.5 to 100 mL withwater. The 50.0 g/L intermediate stock solution in 8.5 will beused as the high standard concentration.10.2 Perform an instrument zero without making an injec-tion.10.3 Set the temperature program (dry, ash/ch
31、ar/pyrolyze,atomize) in accordance with the manufacturers instructions.10.3.1 Sample Size Use 10 to 100 L depending on thegraphite tube size, the concentration, and desired detection4Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestion
32、s on the testing of reagents notlisted by the 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.D6071 132level required. Use the sa
33、me injection volume for the blank,standards, and all samples.10.3.2 Temperature Program:Program stage Temperature, C Time, sDry 100 1 to 3 s/LAsh/char/pyrolize 800 20.0Atomize 2300 4.910.4 Condition the graphite tube surface prior to initiatingthe analysis. Condition the furnace by conducting the fo
34、llow-ing steps.10.4.1 Determine the furnace blank by initiating the atomi-zation program without making an injection. Repeat until thefurnace blank reproduces within 10 % of the initial absorbancevalue obtained.10.4.2 Condition the graphite tube surface by injecting the10 g/L standard. Repeat until
35、the absorbance reproduceswithin 10 %.10.4.3 Inject each of the calibration standards. Reproduc-ibility must be within 10 % for each standard concentration.10.5 Prepare a calibration curve by plotting peak height orpeak area versus concentration as g/L on linear paper if directconcentration readout i
36、s unavailable on the instrument.11. Procedure11.1 Use volumetric plasticware for the preparation of allstandards and samples.11.2 Rinse all the plasticware and equipment with waterprior to use. The analyst may choose to store all plasticware inwater or air dry and store in covered containers.11.3 An
37、alyze the samples as described in Section 10.NOTE 4The analyst should cover the sample containers or use acovered autosampler to minimize the possibility of airborne contaminationbetween injections of the samples into the graphite tube.12. Calculation12.1 Read the sample concentration directly from
38、the instru-ment where applicable or from the calibration curve generatedin 10.5.13. Precision and Bias513.1 The precision and bias for this test method wereobtained in accordance with Practice D2777.13.2 PrecisionThe precision of this test method wasdetermined using high purity water in eight labora
39、tories. Theprecision may be expressed as follows:St5 0.22X!10.88So5 0X!10.91where:St= overall precision,So= single operator precision, andX = determined concentration of sodium, g/L.13.3 BiasMean recoveries of known amounts of sodiumin prepared series of high purity water were as follows:Amountadded
40、, g/LAmount found,g/LBias % BiasStatisticallysignificant0.00 0.16 + 0.16 No0.00 0.40 + 0.40 No1.07 1.03 0.04 4 % No1.42 1.36 0.06 4 % No5.65 5.56 0.09 2 % No7.08 7.14 + 0.06 + 1 % No28.40 28.54 + 0.14 0 % No35.40 40.41 + 5.01 + 14 % No13.4 This section on precision and bias conforms to PracticeD2777
41、 77 which was in place at the time of collaborativetesting. Under the allowances made in 1.4 of D2777 98, theseprecision and bias data do meet existing requirements ofinterlaboratory studies of Committee D19 test methods.14. Quality Control14.1 In order to be certain that analytical values obtainedu
42、sing these test methods are valid and accurate within theconfidence limits of the test, the following QC procedures mustbe followed when analyzing each element.14.2 Calibration and Calibration Verification14.2.1 Analyze five working standards containing concen-trations of silica that bracket the exp
43、ected sampleconcentration, prior to analysis of samples, to calibrate theinstrument. The calibration correlation coefficient shall beequal to or greater than 0.990. In addition to the initialcalibration blank, a calibration blank shall be analyzed at theend of the batch run to ensure contamination w
44、as not a problemduring the batch analysis.i14.2.2 Verify instrument calibration after standardization byanalyzing a standard at the concentration of one of thecalibration standards. The concentration of a mid-range stan-dard should fall within 15 % of the known concentration.14.2.3 If calibration ca
45、nnot be verified, recalibrate theinstrument.14.3 Initial Demonstration of Laboratory Capability14.3.1 If a laboratory has not performed the test before, or ifthere has been a major change in the measurement system, forexample, new analyst, new instrument, and so forth, a precisionand bias study must
46、 be performed to demonstrate laboratorycapability.14.3.2 Analyze seven replicates of a standard solutionprepared from an Independent Reference Material containing amid-range concentration of each element. The matrix andchemistry of the solution should be equivalent to the solutionused in the collabo
47、rative study. Each replicate must be takenthrough the complete analytical test method including anysample preservation and pretreatment steps. The replicates maybe interspersed with samples.14.3.3 Calculate the mean and standard deviation of theseven values and compare to the acceptable ranges of bi
48、as inTable 1. This study should be repeated until the recoveries arewithin the limits given in Table 1. If a concentration other thanthe recommended concentration is used, refer to TestMethodD5847 for information on applying the F test and t testin evaluating the acceptability of the mean and standa
49、rddeviation.14.4 Laboratory Control Sample (LCS)5Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:D19-1160.D6071 13314.4.1 This section on precision and bias conforms toPractice D2777 77 which was in place at the time ofcollaborative testing. Under the allowances made in 1.4 ofD2777 98, these precision and bias data do meet existingrequirements of interlaboratory studies of Committee D19 testmethods.14.4.2 To ensure that the test method is in control, anal
