1、Designation: D 6071 06Standard Test Method forLow Level Sodium in High Purity Water by Graphite FurnaceAtomic Absorption Spectroscopy1This standard is issued under the fixed designation D 6071; the number immediately following the designation indicates the year oforiginal adoption or, in the case of
2、 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. Scope*1.1 This test method covers the determination of tracesodium in high purity water. The method ran
3、ge 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
4、 atomic 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 matr
5、ices.1.4 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 prior to use.2. Referen
6、ced Documents2.1 ASTM Standards:D 1066 Practice for Sampling SteamD 1129 Terminology Relating to WaterD 1192 Guide for Equipment for Sampling Water andSteam in Closed Conduits3D 1193 Specification for Reagent WaterD 2777 Practice for Determination of Precision and Bias ofApplicable Test Methods of C
7、ommittee D19 on WaterD 3370 Practices for Sampling Water from Closed ConduitsD 3919 Practice for Measuring Trace Elements in Water byGraphite Furnace Atomic Absorption SpectrophotometryD 4453 Practice for Handling of Ultra-Pure Water SamplesD 5810 Guide for Spiking into Aqueous SamplesD 5847 Practic
8、e 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 D 1129.4. Summary of Test Method4.1 Sodium is determined by atomic absorption utilizing agraphite furnace
9、 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 environment. The sample is evaporated to dryness,ashed (charred or pyrolyzed)
10、, 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. The amount ofenergy absorbed is proportional to the concentration of
11、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 curve.4.5 A general guide for graphite furnace applications isgiven
12、in Practice D 3919.5. 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 addition, condensate polishing system efflu-ents should have less tha
13、n 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 of Water andWater-Formed Deposits, Analysis of Water for Power Generation and Process Use,On-Line Water Analysis, and Surveill
14、ance of Water.Current edition approved July 1, 2006. Published July 2006. Originally approvedin 1996. Last previous edition approved in 2000 as D 6071 96 (2000).2RP2712 Sub ProgramGrab Sample Method Validation Report Results,Electric Power Research Institute, Palo Alto, CA 1987.3Withdrawn.1*A Summar
15、y of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.absorption spectroscopy (GFAAS) represents technique fordetermining low concentrations of sodium.6. Interferences6.1 No known int
16、erferences from other constituents arefound in high purity waters.6.2 For a complete discussion on interferences with graphitefurnace procedures, refer to Practice D 3919.6.3 Sodium is a common contaminant in many reagents.The analyst must ensure that the quality of the reagent used inthe procedure
17、is sufficiently high to determine trace levels ofsodium.6.4 All plasticware and apparatus must be cleaned andmaintained to eliminate high background levels of sodiumwhen determining trace levels.6.5 Airborne particulates are a potential interference withthe analysis of sodium by GFAAS. The user must
18、 ensure thatall plasticware and other equipment is capped or stored in airtight containers.7. Apparatus7.1 Atomic Absorption Spectrophotometer, with the capabil-ity of setting the following instrumental parameters:Metal Wavelength, nm Slit width (SBW), nmSodium 589.0 0.5NOTE 2The manufacturers instr
19、uctions should be followed for allinstrument parameters.7.2 Hollow Cathode Lamp, for sodium.7.2.1 Multielement hollow cathode lamps may be used ifthe analyst ensures the necessary sensitivity is available for thelow level determination.7.3 Graphite Furnace, capable of reaching temperaturessufficient
20、 to atomize the elements of interest. Maximumsensitivity will be obtained when atomization temperatures arereached rapidly.7.4 Graphite Tubes, compatible with the furnace device.Standard graphite tubes of uncoated graphite should be used.When maximum sensitivity is required, the analyst may chooseto
21、 use pyrolytically coated graphite tubes.7.5 Autosampler, compatible with the graphite furnace de-vice may be used to increase the precision of the 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
22、.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 permanent record of the datain addition to instrument problems (drift, incomplete atomiza-tion, changes in sensitivity, etc.).7.8.1 The strip chart recorder
23、 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 grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specifications of the Commit
24、-tee onAnalytical Reagents of theAmerican Chemical Society.4Other grades may be used, provided it is first ascertained thatthe reagent is of sufficiently high purity to permit its usewithout lessening the accuracy of the determination.8.2 Purity of Water All references to water in this testmethod sh
25、all be understood to mean reagent water conformingto Specification D 1193, Type I.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 wit
26、hwater.8.5 Sodium Solution, standard (1 mL = 0.05 g Na)Dilute5 mL of intermediate 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 conc
27、entration in 8.3.8.6 Argon, 99.99 % pure.9. Sampling9.1 Collect the sample in accordance with Practices D 1066and D 3370 or Specification D 1192.9.2 Samples should be collected in polystyrene, TFE-fluorocarbon or polypropylene bottles only. Do not use glass orpolyethylene containers. The containers
28、should be rinsed withType I water. The container should be stored prior to use byeither air drying and capping or filling with Type I water andcapping. For further details, see Practice D 4453.9.3 To avoid the possibility of contamination, samplesshould not be acidified.10. Calibration10.1 Prepare s
29、tandards for the analytical calibration contain-ing 0.0, 1.0, 5.0, 10.0, and 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 ze
30、ro without making an injec-tion.10.3 Set the temperature program (dry, ash/char/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 detectionlevel required. Use the same injection vo
31、lume 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 4.94Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the test
32、ing 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.D 6071 06210.4 Condition the graphite tube surfa
33、ce prior to initiatingthe analysis. Condition the furnace by conducting the follow-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 Cond
34、ition the graphite tube surface by injecting the10 g/L standard. Repeat until 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 are
35、a versus concentration as g/L on linear paper if directconcentration readout is 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 st
36、ore all plasticware inwater or air dry and store in covered containers.11.3 Analyze 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
37、graphite tube.12. Calculation12.1 Read the sample concentration directly from 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 D 2777.13.2 PrecisionThe prec
38、ision of this test method wasdetermined using high purity water in eight laboratories. Theprecision may be expressed as follows:St5 0.22X! 1 0.88So5 0X! 1 0.91where:St= overall precision,So= single operator precision, andX = determined concentration of sodium, g/L.13.3 BiasMean recoveries of known a
39、mounts of sodiumin prepared series of high purity water were as follows:Amountadded, g/LAmount found,g/L6Bias 6 % 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 4
40、0.41 + 5.01 + 14 % No13.4 This section on precision and bias conforms to PracticeD 2777 77 which was in place at the time of collaborativetesting. Under the allowances made in 1.4 of D 2777 98,these precision and bias data do meet existing requirements ofinterlaboratory studies of Committee D19 test
41、 methods.14. Quality Control14.1 In order to be certain that analytical values obtainedusing 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
42、Analyze five working standards containing concen-trations of silica that bracket the expected sample concentra-tion, prior to analysis of samples, to calibrate the instrument.The calibration correlation coefficient shall be equal to orgreater than 0.990. In addition to the initial calibration blank,
43、 acalibration blank shall be analyzed at the end of the batch runto ensure contamination was not a problem during the batchanalysis.i14.2.2 Verify instrument calibration after standardization byanalyzing a standard at the concentration of one of thecalibration standards. The concentration of a mid-r
44、ange stan-dard should fall within 15 % of the known concentration.14.2.3 If calibration cannot 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 sys
45、tem, forexample, new analyst, new instrument, and so forth, a precisionand bias study must 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 m
46、atrix andchemistry of the solution should be equivalent to the solutionused in the collaborative 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
47、 mean and standard deviation of theseven values and compare to the acceptable ranges of bias 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 Test MethodD 5847 for informa
48、tion on applying the F test and t test inevaluating the acceptability of the mean and standard devia-tion.14.4 Laboratory Control Sample (LCS)14.4.1 This section on precision and bias conforms toPractice D 2777 77 which was in place at the time ofcollaborative testing. Under the allowances made in 1
49、.4 ofD 2777 98, these precision and bias data do meet existingrequirements of interlaboratory studies of Committee D19 testmethods.5Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR: D191160.D 6071 06314.4.2 To ensure that the test method is in control, analyzea LCS containing a known concentration of silica with eachbatch or 10 samples. If large numbers of samples are analyzedin the batch, analyze the LCS after every 10 samples. Thelaboratory control samples
