1、Designation: D5085 02 (Reapproved 2013)Standard Test Method forDetermination of Chloride, Nitrate, and Sulfate inAtmospheric Wet Deposition by Chemically Suppressed IonChromatography1This standard is issued under the fixed designation D5085; the number immediately following the designation indicates
2、 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 This test method is applicable to the determina
3、tion ofchloride, nitrate, and sulfate in atmospheric wet deposition(rain, snow, sleet, and hail) by chemically suppressed ionchromatography (1)2. For additional applications refer to TestMethod D4327.1.2 The concentration ranges for this test method are listedbelow. The range tested was confirmed us
4、ing the interlabora-tory collaborative test (see Table 1 for statistical summary ofthe collaborative test).MDL (mg/L) (2)Range ofMethod(mg/L)RangeTested(mg/L)Chloride 0.03 0.092.0 0.151.36Nitrate 0.03 0.095.0 0.154.92Sulfate 0.03 0.098.0 0.156.521.3 The method detection limit (MDL) is based on singl
5、eoperator precision (2) and may be higher or lower for otheroperators and laboratories. The precision and bias data pre-sented are insufficient to justify use at this low level, however,many workers have found that this test method is reliable atlower levels than those that were tested.1.4 This stan
6、dard 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. Specific precau-tionary sta
7、tements are given in Section 9.2. Referenced Documents2.1 ASTM Standards:3D883 Terminology Relating to PlasticsD1129 Terminology Relating to WaterD1193 Specification for Reagent WaterD1356 Terminology Relating to Sampling and Analysis ofAtmospheresD2777 Practice for Determination of Precision and Bi
8、as ofApplicable Test Methods of Committee D19 on WaterD3670 Guide for Determination of Precision and Bias ofMethods of Committee D22D4210 Practice for Intralaboratory Quality Control Proce-dures and a Discussion on Reporting Low-Level Data(Withdrawn 2002)4D4327 Test Method for Anions in Water by Sup
9、pressed IonChromatographyD5012 Guide for Preparation of Materials Used for theCollection and Preservation of Atmospheric Wet Deposi-tionIEEE/ASTM SI-10 Standard for Use of the InternationalSystem of Units (SI): The Modern Metric SystemE694 Specification for Laboratory Glass Volumetric Appa-ratus3. T
10、erminology3.1 DefinitionsFor definitions of terms used in this testmethod, refer to Terminologies D883, D1129, and D1356 andTest Method D4327 and Practice IEEE/ASTM SI-10.4. Summary of Test Method4.1 Ion chromatography combines conductometric detectionwith the separation capabilities of ion exchange
11、 resins. (1) A1This test method is under the jurisdiction of ASTM Committee D22 on AirQuality and is the direct responsibility of Subcommittee D22.03 on AmbientAtmospheres and Source Emissions.Current edition approved Oct. 1, 2013. Published October 2013. Originallyapproved in 1990. Last previous ed
12、ition approved in 2008 as D5085 02 (2008).DOI: 10.1520/D5085-02R13.2The boldface numbers in parentheses refer to references at the end of this testmethod.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMS
13、tandards volume information, refer to the standards Document Summary page onthe ASTM website.4The last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1filtered
14、aliquot of the sample, ranging in size from 50 to 250L, is pumped through an ion exchange column where theanions of interest are separated. Each ions affinity for theexchange sites, known as its selectivity quotient, is largelydetermined by its radius and valence. Because different ionshave differen
15、t selectivity quotients, the sample ions elute fromthe column as discrete bands. Each ion is identified by itsretention time within the exchange column. The sample ionsare selectively eluted off the separator column and onto asuppressor column, where the conductivity of the eluent ions isreduced and
16、 the sample ions are converted to their correspond-ing strong acids. The separated anions are detected by aconductance cell. The chromatograms produced are displayedon a strip chart recorder or other data acquisition device.Measurement of peak height or area is used for quantitation.The ion chromato
17、graph is calibrated with standard solutionscontaining known concentrations of the anion(s) of interest.Calibration curves are constructed from which the concentra-tion of each analyte in the unknown sample is determined. Foradditional information on ion chromatography refer to TestMethod D4327.5. Si
18、gnificance and Use5.1 This test method is useful for the determination of theanions: chloride, nitrate, and sulfate in atmospheric wet depo-sition.5.2 Fig. X1.1 in the appendix represents cumulative fre-quency percentile concentration plots of chloride, nitrate, andsulfate obtained from analyses of
19、over 5000 wet depositionsamples. These data may be used as an aid in the selection ofappropriate calibration solutions. (3)6. Interferences6.1 Unresolved peaks will result when the concentration ofone of the sample components is 10 to 20 times higher thananother component that appears in the chromat
20、ogram as anadjacent peak. Decreasing the eluent concentration or flow rate,increasing column length, or decreasing sample size maycorrect this problem.6.2 Interferences may be caused by ions with retentiontimes that are similar to the anion of interest.The retention timeof sulfite may be similar to
21、nitrate or sulfate. Other possibleinterfering ions are bromide and phosphate. Before analyzingprecipitation samples, measure the retention times of thesepossible interfering ions. Interference is common in some typesof wet deposition samples. If this interference is anticipated,decreasing the eluent
22、 concentration or flow rate, increasingcolumn length, or decreasing sample size will result in im-proved peak resolution.6.3 Water from the sample injection will cause a negativepeak (water dip) in the chromatogram when it elutes becauseits conductance is less than that of the suppressed eluent.Chlo
23、ride may elute near the water dip and must be sufficientlyresolved from the dip to be accurately quantified. This can beachieved by changing the eluent concentration or decreasingthe flow rate. The potential interference of the negative peakcan be eliminated by adding an equivalent of 100 l of aprep
24、ared eluent concentrate (solution that is 100 times moreconcentrated than the eluent used for analysis) per 10.0 mL ofsample. Identical eluent additions must also be included incalibration and quality control solutions.6.4 Decreases in retention times and resolution are symp-toms of column deteriora
25、tion which may be caused by thebuildup of contaminants on the exchange resin. Refer to themanufacturers guidelines for instructions on cleaning thecolumn resin and column filter beds. Excising the contami-nated portion of the column and changing the filters may alsoimprove performance. If the proced
26、ure in this section do notrestore the retention times, replace the column.6.5 Contaminated valves and sample lines may also reducesystem performance causing decreased retention times andTABLE 1 Precision and Bias for Chloride, Nitrate, and Sulfate Determined from the Synthetic Atmospheric Wet Deposi
27、tion SamplesUsed in the Interlaboratory Comparison StudyAnalyteAmountAdded,mg/LMeanRecovery,mg/LnAPrecision mg/LBias,mg/LSignificantBiasBStC95 %ReproducibilityLimitSoD95 %RepeatabilityLimitChloride 0.15 0.157 36 0.0535 0.150 0.0116 0.0325 0.007 no0.30 0.293 35 0.0554 0.155 0.0291 0.0815 0.007 no0.68
28、 0.652 36 0.0549 0.154 0.0237 0.0664 0.028 biased low1.36 1.368 36 0.1 0.28 0.0431 0.121 0.008 noNitrate 0.15 0.138 24 0.0362 0.101 0.0289 0.0809 0.012 no1.08 1.077 24 0.0495 0.139 0.0421 0.118 0.003 no2.44 2.486 22 0.0197 0.0552 0.0183 0.0512 0.046 biased high4.92 4.999 24 0.126 0.353 0.075 0.21 0.
29、079 biased highSulfate 0.15 0.172 36 0.055 0.154 0.0304 0.085 0.022 no1.43 1.442 35 0.0683 0.191 0.0369 0.103 0.012 no3.23 3.358 36 0.13 0.364 0.046 0.129 0.128 biased high6.52 6.775 36 0.37 1.04 0.109 0.305 0.255 biased highANumber of samples included in final statistical analysis after removal of
30、outlier data.B95 % confidence level.CBetween laboratory precision, reproducibility.DWithin laboratory precision (pooled single operator precision), repeatability.D5085 02 (2013)2resolutions. Refer to the manufacturers guidelines for instruc-tions on cleaning the valves and replacing the lines.NOTE 1
31、Review operational details and refer to the trouble shootingguide in the Operators Manual to determine the cause of decreasedretention times and resolution prior to extensive cleaning or changing ofall valves, columns, filters, sample lines, or all of the above.6.6 The presence of air bubbles in the
32、 columns, tubing, orconductivity detector cell may cause baseline fluctuations andpeak variability. Prevent introducing air into the system wheninjecting samples and standards. The use of degassed water foreluents and regenerants may help to minimize the introductionof air (See 8.2).6.7 For more inf
33、ormation on interferences refer to TestMethod D4327.7. Apparatus7.1 Ion ChromatographSelect an instrument equippedwith an injection valve, a sample loop, separator column(s),suppressor column(s), pump(s), and detector meeting require-ments specified. Peripheral equipment includes compressedgas, a su
34、itable data acquisition device such as a strip chartrecorder, an integrator, or computer, and may include anautomatic sampler.7.1.1 TubingTubing that comes in contact with samplesand standards must be manufactured from inert material suchas polyethylene plastics or TFE-fluorocarbon.7.1.2 Anion Guard
35、 ColumnAlso called a precolumn, it isplaced before the separator column. The guard column con-tains the same resin as the separator column and is used toprotect it from being fouled by particulates or organic constitu-ents. Using an anion guard column will prolong the life of theseparator column.57.
36、1.3 Anion Separator ColumnThis is a column packedwith a pellicular low-capacity anion exchange resin con-structed of polystyrene-divinylbenzene beads coated with quar-tenary ammonium active sites.67.1.4 Anion Suppressor ColumnPlace following the sepa-rator column. This may be in the form of an anion
37、 micro-membrane suppressor or an anion self-regenerating suppressor.The first type of suppressor utilizes a semipermeable mem-brane containing anion exchange sites to suppress eluentconductance.7The second type of suppressor uses the neutral-ized cell effluent as the source of water for the regenera
38、ntchamber water.7.1.5 Compressed Gas (Nitrogen or Air)Use ultra-highpurity 99.999 % (v/v) compressed gas that is oil, particulate,and water free to actuate the valves and to pressurize theregenerant flow system as needed.7.1.6 DetectorSelect a flow-through, temperature-compensated, electrical conduc
39、tivity cell with a volume ofapproximately 6 L coupled with a meter capable of readingfrom 0 to 1000 s/cm on an analog or digital scale.7.1.7 PumpUse a pump capable both of delivering aconstant flow rate of approximately 1 to 5 mL/min and oftolerating a pressure 1379 to 13 790 kPa. A constant pressur
40、e,constant flow pump is recommended for enhanced baselinestability.All interior pump surfaces that will be in contact withsamples and standards must be manufactured from inert,non-metallic materials.7.1.8 Data Acquisition System:7.1.8.1 RecorderThis must be compatible with the maxi-mum conductance d
41、etector output with a full-scale responsetime of 0.5 s or less. A two pen recorder with variable voltageinput settings is recommended.7.1.8.2 IntegratorIf an integrating system is employed,the data acquisition unit must be compatible with the maximumdetector output to quantitate the peak height or a
42、rea. If anintegrator is used, the maximum peak height or area measure-ment must be within the linear range of the integrator.7.1.9 Sample LoopSelect a sample loop with a capacity of50 to 250 L.7.1.10 Sample Introduction SystemSelect one of the fol-lowing:7.1.10.1 SyringeA syringe equipped with a mal
43、e fittingwith a minimum capacity of 2 mL.7.1.10.2 AutosamplerAn autosampling system capable ofprecise delivery, equipped with a dust cover to reduce airbornecontamination.7.2 Eluent and Regenerant ReservoirsSelect containerswitha4to20Lcapacity that are designed to minimizeintroduction of air into th
44、e flow system for storing eluents andregenerants.7.3 GlasswareGlassware, including volumetric pipettesand flasks, must be dedicated for use on atmospheric wetdeposition samples only. Volumetric pipettes should be used tomeasure the stock solutions.The pipettes may be either fixed orvariable volume a
45、nd either glass or plastic. Volumetric glass-ware must meet the requirement for Class A items given inSpecification E694. Pipettes with disposable tips are preferredin order to reduce contamination. The pipettes must have aprecision and a bias of 1 % or better. Precision and bias aredetermined by we
46、ighing a minimum of ten separately pipettedaliquots.7.4 Laboratory FacilitiesLaboratories used for the analy-sis of wet deposition samples must be free from sources ofcontamination. The use of laminar flow clean air work stationsis recommended for sample processing and preparation toavoid the introd
47、uction of airborne contaminants. Samples mustalways be capped or covered prior to analysis. A positivepressure environment within the laboratory is also recom-mended to minimize the introduction of external sources ofcontaminant gases and particulates. Room temperature fluctua-tions must be controll
48、ed to within 6C to prevent baseline driftand changes in detector response. Windows within the labora-tory must be kept closed at all times and sealed if air leaks areapparent. The use of disposable tacky floor mats at the entranceto the laboratory is helpful in reducing the particulate loadingwithin
49、 the room.5Dionex P/N 030986 (AG3) available from Dionex Corp., 1228 Titan Way, POBox 3603, Sunnyvale, CA, 94088-3603, or equivalent has been found to besatisfactory.6Dionex P/N 030985 (AS3) available from Dionex Corp., 1228 Titan Way, POBox 3603, Sunnyvale, CA, 94088-3603, or equivalent has been found to besatisfactory.7Dionex P/N 35350 (AFS) or Dionex P/N 38019 (AMMS) available fromDionex Corp., 1228 Titan Way, PO Box 3603, Sunnyvale, CA, 94088-3603, orequivalent has been found to be satisfactory.D5085 02 (2013)38. Reagents and Materials8.1
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