ASTM D6317-2015 red 7693 Standard Test Method for Low Level Determination of Total Carbon Inorganic Carbon and Organic Carbon in Water by Ultraviolet Persulfate Oxidation and Membr.pdf

1、Designation: D6317 98 (Reapproved 2009)D6317 15Standard Test Method forLow Level Determination of Total Carbon, Inorganic Carbonand Organic Carbon in Water by Ultraviolet, PersulfateOxidation, and Membrane Conductivity Detection1This standard is issued under the fixed designation D6317; the number i

2、mmediately following 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 () indicates an editorial change since the last revision or reapproval.1. Scope1.1 T

3、his test method covers the determination of total carbon (TC), inorganic carbon (IC), and total organic carbon (TOC) inwater in the range from 10 to 1000 g/L of carbon. This method is for laboratory or grab sample applications and has beensubjected to an interlaboratory study under the guidelines of

4、 D2777. Test Method D5997 can be used for on-line determinations.The test method utilizes persulfate or ultraviolet oxidation of organic carbon, or both coupled with a CO2 selective membrane torecover the CO2 into deionized water. The change in conductivity of the deionized water is measured and rel

5、ated to carbonconcentration in the oxidized sample. Inorganic carbon is determined in a similar manner without the oxidation step. In both cases,the sample is acidified to facilitate CO2 recovery through the membrane. The relationship between the conductivity measurementand carbon concentration is d

6、escribed by a set of chemometric equations for the chemical equilibrium of CO2, HCO3 , and H+,and the relationship between the ionic concentrations and the conductivity. The chemometric model includes the temperaturedependence of the equilibrium constants and the specific conductances resulting in l

7、inear response of the method over the statedrange of TOC. See Test Method D4519 for a discussion of the measurement of CO2 by conductivity.1.2 This test method has the advantage of a very high sensitivity detector that allows very low detection levels on relativelysmall volumes of sample. Also, use

8、of two measurement channels allows determination of CO2 in the sample independently oforganic carbon. Isolation of the conductivity detector from the sample by the CO2 selective membrane results in a very stablecalibration, with minimal interferences.1.3 This test method was used successfully with r

9、eagent water spiked with various organic materials. It is the usersresponsibility to ensure the validity of this test method for waters of untested matrices.1.4 In addition to laboratory analyses, this test method may be adapted to on line monitoring. See Test Method D5997.1.5 The values stated in S

10、I units are to be regarded as standard. No other units of measurement are included in this standard.1.6 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 heal

11、th practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D1129 Terminology Relating to WaterD1192 Guide for Equipment for Sampling Water and Steam in Closed Conduits (Withdrawn 2003)3D1193 Specification for Reagent WaterD2777 Pract

12、ice for Determination of Precision and Bias of Applicable Test Methods of Committee D19 on WaterD3370 Practices for Sampling Water from Closed ConduitsD4210 Practice for Intralaboratory Quality Control Procedures and a Discussion on Reporting Low-Level Data (Withdrawn2002)31 This test method is unde

13、r the jurisdiction of ASTM Committee D19 on Water and is the direct responsibility of Subcommittee D19.03 on Sampling Water andWater-Formed Deposits, Analysis of Water for Power Generation and Process Use, On-Line Water Analysis, and Surveillance of Water.Current edition approved Oct. 1, 2009May 1,

14、2015. Published November 2009August 2015. Originally approved in 1998. Last previous edition approved in 20042009as D6317 98 (2004).(2009). DOI: 10.1520/D6317-98R09.10.1520/D6317-15.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.or

15、g. 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.This document is not an ASTM standard and is intended only to provide the user of an ASTM sta

16、ndard 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 users consult prior editions as appropriate. In all cases only the current versionof the standard as published by AS

17、TM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1D5997 Test Method for On-Line Monitoring of Total Carbon, Inorganic Carbon in Water by Ultraviolet, Persulfate Oxidation,and Membrane Conduct

18、ivity DetectionD4519 Test Method for On-Line Determination of Anions and Carbon Dioxide in High Purity Water by Cation Exchange andDegassed Cation Conductivity3. Terminology3.1 DefinitionsFor definitions of terms used in this test method, refer to Terminology D1129.3.2 Definitions of Terms Specific

19、to This Standard:3.2.1 inorganic carbon (IC)(IC), ncarbon in the form of carbon dioxide, carbonate ion, or bicarbonate ion.3.2.2 refractory materialmaterial, nthat which cannot be oxidized completely under the test method conditions.3.2.3 total carbon (TC)(TC), nthe sum of IC and TOC.3.2.4 total org

20、anic carbon (TOC)(TOC), ncarbon in the form of organic compounds.4. Summary of Test Method4.1 Carbon can occur in water as inorganic and organic compounds. This test method can be used to make independentmeasurements of IC and TC and can also determine TOC as the difference of TC and IC. If IC is hi

21、gh relative to TOC it is desirableto use a vacuum degassing unit to reduce the IC concentration as part of the measurement. Alternatively, the IC can be removedby acidifying and sparging the sample prior to injection into the instrument. The basic steps of the procedure are as follows:(1) Removal of

22、 IC, if desired, by vacuum degassing;(2) Conversion of remaining inorganic carbon to CO2 by action of acid in both channels and oxidation of total carbon to CO2by action of ultraviolet (UV) radiation in the TC channel. (Acid-persulfate can be added but is usually not required at TOC levelsbelow 1 pp

23、m).(3) Detection of CO2 that is swept out of the U.V.UVreactor and delay coil by the liquid stream and passed through membranesthat allow the specific passage of CO2 to high purity water where change in conductivity is measured and;(4) Conversion of the conductivity detector signal to a display of c

24、arbon concentration in parts per million (ppm=mg/L) (ppm= mg/L) or parts per billion (ppb=g/L). (ppb = g/L). The IC channel reading is subtracted from the TC channel to give a TOCreading. A diagram of suitable apparatus is given in Fig. 1. References 1-54 provide additional information on the method

25、.5. Significance and Use5.1 This test method is used for determination of the carbon content of water from a variety of natural, domestic, and industrialsources. In its most common form, this test method is used to measure organic carbon as a means of monitoring organic impuritiesin high purity proc

26、ess water used in industries such as nuclear power, pharmaceutical, and electronics.6. Interferences and Limitations6.1 The oxidation of dissolved carbon to CO2 is brought about at relatively low temperatures by the chemical action of reactivespecies produced by UV-irradiated persulfate ions and wat

27、er. Not all suspended or refractory material may be oxidized under theseconditions; analysts should take steps to determine what recovery is being obtained. This may be done by several methods: byrerunning the sample under more vigorous reaction conditions or by spiking samples with known refractori

28、es and determiningrecovery.6.2 Chloride ion above 250 mg/L tends to interfere with oxidative reaction mechanisms in this test method. Followmanufacturers instructions for dealing with this problem. Other interferences have been investigated and found to be minimalunder most conditions. Refer to the

29、reference (2) for more information.6.3 Note that error will be introduced when the method of difference is used to derive a relatively small level from two largelevels. In this case the vacuum degassing unit on the instrument should be used to reduce the concentration of IC prior tomeasurement. Alte

30、rnatively, the sample can be acidified and sparged prior to introduction into the instrument.6.4 Use of the vacuum degassing unit or sparging the sample may cause loss of volatile organic compounds, thus yielding avalue lower than the true TOC level.At low TOC levels, the degassing unit may introduc

31、e a measurable TOC and IC background.The user should characterize the background and performance of the degassing module for their application. Table 1 providestypical IC removal performance and background levels of the vacuum degassing unit.6.5 Contamination of the sample with both CO2 and organic

32、carbon is a severe problem as lower levels of analyte are attempted.Throughout this method, the analyst must be vigilant for all potential sources of contamination and must monitor blanks and adjustoperations to prevent contamination.4 The boldface numbers in parentheses refer to the list of referen

33、ces found at the end of this test method.D6317 152FIG. 1 Schematic Diagram of TOC Analyzer SystemTABLE 1 Blank Contribution and IC. Removal Efficiency ofVacuum Degassing Unit.UnitNo.g/LA TOCbackgroundg/LA ICbackgroundIC level with 25 000g/L input1 3.2 8.2 552 3.2 22 613 2.4 8.0 1054 4.2 13 895 2.8 1

34、3 306 3.0 8.0 707 4.8 8.9 678 4.7 8.3 639 4.6 11 6210 4.7 2.9 72A Values are the difference between before and after addition of the degasser to ahigh purity (5 g/L) water stream.D6317 1536.6 The membrane conductivity detection technique may experience positive interference in the presence of low mo

35、lecularweight, reduced, inorganic acid species such as H2S or HNO2. Such interferences can be eliminated by oxidation or removal ofthe gas.7. Apparatus7.1 Apparatus for Carbon DeterminationA typical instrument consists of reagent and sample introduction mechanism,reaction vessel, detector, control s

36、ystem, and a display.5Fig. 1 shows a diagram of such an arrangement.7.1.1 Sampling NeedleA double chambered needle capable of piercing the sample bottle septum and pulling sample from thebottom of the bottle is used. The second chamber vents the top of the bottle to prevent vacuum build up as the sa

37、mple is withdrawn.Typically this needle is mounted on an autosampler to provide unattended analysis of several samples.7.1.2 I.C.IC RemovalVacuum degassing requires the manufacturers module5 which includes a vacuum pump and a hollowfiber membrane assembly. Use of this vacuum degasser will remove ess

38、entially all IC as part of the analysis. The membranemodule consists of a tube and shell arrangement of microporous polypropylene hollow fibers. Sample flows along the inside ofthe fibers, while air is passed on the shell side-counterflow to the sample flow. The shell side pressure is reduced by mea

39、ns of avacuum pump on the air outlet. The sample is acidified before introduction into the degasser to facilitate CO2 transport throughthe hollow fibers. Sparging requires an inert vessel with provision for sparging the acidified sample with 50 to 100 mL/min ofcarbon free gas. This procedure will re

40、move essentially all IC in 2 to 10 min, depending on design.7.1.3 ReactorThe sample flow is split after the addition of reagents. Half of the flow passes to the delay coil while the otherhalf passes into the oxidation reactor. The effluent from both streams passes over individual membranes that allo

41、w CO2 to pasthrough the membrane into prepurified water for detection.7.1.4 MembraneThe membrane is a CO2 selective fluoropolymer which is hydrophobic and non-porous. Refer to thebibliography for additional details.7.1.5 DetectorThe CO2 that has passed through the membrane into the purified water is

42、 measured by conductivity sensors.The temperature of the conductivity cell is also automatically monitored so the readings can be corrected for changes intemperature.7.1.6 Data DisplayThe conductivity detector output is related to stored calibration data and then displayed as parts permillion, (ppm

43、= mg of carbon per litre) or parts per billion, (ppb = g of carbon per L).litre). Values are given for TC, IC, and TOCby difference.8. Reagents and Materials8.1 Purity of ReagentsReagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that allreagents conform t

44、o the specifications of the Committee on Analytical Reagents of the American Chemical Society,6 where suchspecifications are available. Other grades may be used, provided it is first ascertained that the reagent is of sufficient purity to permitits use without lessening the accuracy of the determina

45、tion.8.2 Purity of WaterUnless otherwise indicated, references to water shall be understood to mean reagent water conforming toType I or Type II in Specification D1193. The indicated specification does not actually specify inorganic carbon or organic carbonlevels. These levels can affect the results

46、 of this test method, especially at progressively lower levels of the carbon content in thesamples to be measured. Where inorganic carbon in reagent water is significant, CO2-free water may be prepared from reagentwater by acidifying to pH 2, then sparging with fritted-glass sparger using CO2-free g

47、as (time will depend on volume and gas flowrate, and should be determined by test). The carbon contribution of the reagent water should be determined and its effect allowedfor in preparation of standards and other solutions. CO2-free water should be protected from atmospheric contamination. Glasscon

48、tainers are required for storage of water and standard solutions. Continuous U.V.UV treatment of water with recycling throughappropriate mixed bed ion exchange resins may be necessary to maintain an adequately low TOC reagent water.8.3 Persulfate Reagent (15 % w/v)Prepare ammonium persulfate solutio

49、n to a concentration of 15 % w/v by dissolving 15 gof ammonium peroxydisulfate in water and diluting to 100 mL. Verify that it contains less than 2000 g/L organic carboncontamination. Certification of reagent assay should be available. Reagents in prepackaged containers from the instrumentmanufacturer have been found to be acceptable.8.4 Acid Reagent (6M)(6 M)Prepare acid solution to a concentration of 6M and verify that it contains less than 600 g/Lorganic carbon contamination. Since halogens are potential interferences, use only sulfuric or p