1、Designation: D 5012 01Standard Guide forPreparation of Materials Used for the Collection andPreservation of Atmospheric Wet Deposition1This standard is issued under the fixed designation D 5012; the number immediately following the designation indicates the year oforiginal adoption or, in the case o
2、f 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. Scope1.1 This guide presents recommendations for the cleaningof plastic or glass materials used for co
3、llection of atmosphericwet deposition (AWD). This guide also presents recommenda-tions for the preservation of samples collected for chemicalanalysis.1.2 The materials used to collectAWD for the analysis of itsinorganic constituents and trace elements should be plastic.High density polyethylene (HDP
4、E) is most widely used and isacceptable for most samples including samples for the deter-mination of the anions of acetic, citric, and formic acids.Borosilicate glass is a collection alternative for the determina-tion of the anions from acetic, citric, and formic acid; it isrecommended for samples f
5、or the determination of otherorganic compounds.1.3 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 regu
6、latory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 883 Terminology Relating to PlasticsD 1125 Test Methods for Electrical Conductivity and Re-sistivity of WaterD 1129 Terminology Relating to WaterD 1193 Specification for Reagent WaterD 1356 Terminology Relating to Sampling
7、and Analysis ofAtmospheresD 1695 Terminology of Cellulose and Cellulose DerivativesD 2914 Test Methods for Sulfur Dioxide Content of theAtmosphere (West-Gaeke Method)D 4453 Practice for Handling of Ultra-Pure Water Samples3. Terminology3.1 Definitions:3.1.1 For definitions of terms used in this guid
8、e, refer toTerminology D 1129.3.1.2 For definition of plastic refer to Terminology D 1695and Terminology D 883.3.1.3 For definition of AWD (precipitation, meteorologi-cal) refer to Terminology D 1356.4. Significance and Use4.1 Some chemical constituents of AWD are not stable andmust be preserved bef
9、ore chemical analysis. Without samplepreservation, it is possible that analytes can be lost throughdecomposition or sorption to the storage bottles.4.2 Contamination of AWD samples can occur during bothsample preservation and sample storage. Proper selection andcleaning of sampling containers are re
10、quired to reduce thepossibility of contamination of AWD samples.4.3 The natural sponge and talc-free plastic gloves used inthe following procedures should be recognized as potentialsources of contamination. Individual experience should beused to select products that minimize contamination.5. Apparat
11、us5.1 Instruments shall be selected in accordance with anapplicable test method given in Test Methods D 1125.5.2 The conductivity cell shall be pipet or dip type with acell constant (K) of 0.1 .6. Reagents and Materials6.1 Purity of ReagentsReagent grade acids and otherchemicals shall be used to red
12、uce the risk of contaminating theAWD samples. Unless otherwise indicated, it is intended thatall reagents conform to the specifications of the Committee onAnalytical Reagents of the American Chemical Society wheresuch specifications are available.31This guide is under the jurisdiction of ASTM Commit
13、tee D22 on Air Qualityand is the direct responsibility of Subcommittee D22.03 on Ambient Atmospheresand Source Emissions.Current edition approved Ocotober 10, 2001. Published December 2001.Originally published as D 5012 89. Last previous edition D 5012 94.2For referenced ASTM standards, visit the AS
14、TM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. F
15、or suggestions 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. Pharmaceutical Convention, Inc. (USPC), Rockville,MD.1Copyright ASTM Inter
16、national, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6.2 Nitric acid, ultra pure.6.3 Nitric acid (1+9)Dilute 1 volume concentrated nitricacid with 9 volumes of water.6.4 Chloroform, high performance liquid chromatographyreagent.6.5 Hydrochloric acid, preteste
17、d for total and methyl mer-cury.6.6 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean reagent water as definedby Type I of Specification D 1193. AWD samples collected fororganic analysis may require Type II (distilled) reagent water.7. Sample Preservation7.1 I
18、nteraction between the sample and the atmosphere mustbe minimized. The sample container should be sealed as soonas possible after collection or sub-sampling.AWD samples canbe easily contaminated because of the low concentration levelsof their analytes. Trace metals, and possibly other ions inAWDsamp
19、les, can be lost through sorption with the bottle orcontainer in which they are stored. AWD samples may containbiologically active microorganisms which could affect theconcentration of many analytes. Immediate analysis of AWDsamples is best and chemical preservation should be used onlywhen the prese
20、rvation is shown not to interfere with theanalysis being performed. Samples collected for total andmethyl mercury determinations are to be collected directly intospecially cleaned, pretested, fluoropolymer bottle(s) (19 and20).47.2 Samples Collected for Inorganic Cation and AnionDeterminations:7.2.1
21、 Samples collected for pH, specific conductance, cal-cium, magnesium, potassium, sodium, chloride, fluoride, andsulfate analysis are often only placed in pre-cleaned plasticcontainers (see Section 8) before analysis. If there is a delaybetween time of collection and time of analysis, a preservationt
22、echnique may eliminate or moderate chemical and biologicalchanges in the AWD samples. Table 1 summarizes the recom-mended sample preservation techniques for AWD samples.7.3 Samples Collected for Organic Acids:7.3.1 Samples collected for the analysis of acetate, citrate,formate and other low molecula
23、r weight organic acid anions(C1-C12) should be preserved within minutes after collection.Organic acids have been determined inAWD samples collectedfrom locations around the world (1-7). These compounds (inparticular formic and acetic acids) can constitute from a smallfraction to mostly all of the fr
24、ee acidity in AWD samples.4The boldface numbers in parentheses refer to the list of references at the end ofthis standard.TABLE 2 Preservation of AWD Samples Collected for Organic Acid DeterminationsPreservation Technique Species Determined Remarks ReferenceChloroform Acetate, citrate, formate,C1C5A
25、nalysis is usually by ion-exclusion chromatography because chloroform mayinterfere with capillary GC-MS analysis. This preservative is often coupled withsample storage at 4C. When chloroform treatment is combined with storage inthe dark at 4C, samples are reportedly stable for 60 days. Final chlorof
26、ormconcentration in the AWD sample must be 0.2 % by weight.(3,4)Freeze at 20C Short-chain dicarboxylic acidsC2C12Analysis is by capillary gas chromatography or GC-MS. Sample must becompletely in the liquid state before sample is prepared for analysis. Maximumstorage time has not been reported.(6)Chi
27、ll at 4C Low molecular weight acids This is a minimum procedure for organic acid preservation. This preservationtechnique will not preserve acetate and formate longer than 3 days.Degradation may occur in less than 3 days.(7)TABLE 1 Preservation of AWD Samples Collected for Inorganic Cation and Anion
28、 DeterminationsPreservation Technique Species Determined Remarks ReferenceNo preservation All inorganic cations andanionsRapid analysis is required after collection because ion concentrations maychange in samples. Ammonium, nitrate, and ortho-phosphate concentrationsmay be reduced in samples that ar
29、e biologically active. Cation and trace metalconcentrations may be reduced by sorption onto container surfaces.(10-14)Refrigerate 4C All inorganic cations andanionsChilling may reduce the loss of ammonium, nitrate, and ortho-phosphate insamples that are biologically active. Samples must be allowed t
30、o come toambient temperature (2327C) before performing pH and specificconductance determinations. Specific conductance and pH determinationsshould be performed on-site as soon as possible after sample collection.(15-17)HNO3pH # 2Ca2+,Mg2+,Na+,K+Samples must first be filtered, or acid addition may di
31、ssolve particles in theAWD samples (see 7.4.1). Acid addition will interfere with anion determination,so a separate aliquot will be needed for other ion determinations.(11,12)HCl, 5 mL/L All dissolved Hg and total Hg Samples for dissolved Hg are filtered through 0.45 m capsule filter. Samplescollect
32、ed directly into specially cleaned, pretested, fluoropolymer bottle.(19,20)Filtration All inorganic cations andanionspH and specific conductance determinations may be affected by filtration. Caremust be taken to minimize the possibility of sample contamination duringfiltration.(18)D5012012Because th
33、ese acids are unstable in AWD samples, samplesmust be analyzed within hours after collection or else apreservation technique is required. Table 2 summarizes therecommended sample preservation techniques for AWDsamples.7.4 Samples Collected for Trace Dissolved Metals:7.4.1 Samples collected for trace
34、 metals should be filtered toremove insoluble particulate matter often found in AWDsamples unless an AWD particulate trace element analysis isdesired. Filter pore size should be #0.45 m. Filter materialsmay contain trace elements, and the filters should be precon-ditioned before use by filtering 300
35、 mL of water in order toleach soluble impurities on the filter and from the filtrationapparatus itself (8). Any filters used for AWD samples shouldbe tested to determine if the filter causes losses or gains of traceelements to theAWD sample. Test the preconditioned filters byfiltering 50 mL of water
36、 and determine the analyte concentra-tions of interest in the filtrate.7.4.2 Acidify the AWD sample with nitric acid to pH #2tominimize container adsorption of trace metals. The highestpurity acid available should be used. Most AWD samples arepoorly buffered and only small quantities of acid (about
37、1mL/L) are required to reduce the AWD sample to a pH #2.Samples acidified with an acid may not be used for thedetermination of pH and certain other analytes.7.4.3 Acidify the AWD sample with 5 mL/L of pretestedHCl for dissolved mercury and total mercury.8. Sample Containers8.1 ManyAWD sampling netwo
38、rks use samplers that utilizeeither a bucket or bottle that is an integral component of theAWD samplers. These collection techniques allow “wet-only”samples to be obtained, meaning the bucket or bottle is onlyexposed to the atmosphere during the precipitation event. Thepreparation or cleaning proced
39、ures described in Section 8apply to the automatedAWD samplers that use buckets, and thesample storage bottles to which the AWD sample is transferredfrom the collection bucket. The procedure described in 8.3could also be used as a cleaning procedure for AWD samplingthat uses a bottle as the principal
40、 collection container.NOTE 1Any materials used for the collection and preservation ofAWD should be dedicated to the use intended.8.2 Inorganic IonsBuckets and Lids:8.2.1 Sample containers shall be made of materials that willnot contaminate the sample and shall be cleaned thoroughlybefore use. Plasti
41、c containers of polyethylene and polypropy-lene are recommended for AWD samples collected for inor-ganic ions. HDPE is most commonly used.8.2.2 Wipe the exterior of the bucket with damp cloth orbrush.8.2.3 Clean collector buckets and lids only with water. Theinside of the bucket and inner side of th
42、e lid should not comeinto contact with any object other than a natural sponge that hasbeen preconditioned with water by soaking the sponge for atleast 24 h.NOTE 2The initial preparation procedure for newly obtained naturalsponges requires that the sponge is washed with copious amounts of waterat lea
43、st four times. Soaking a new natural sponge in 4 L of water for twoor three days, after washing, is suggested.8.2.4 Rinse the interior of the bucket two or more times withwater using 100 mL for each rinse.8.2.5 Place at least 1000 mL of water in the bucket.8.2.6 Scrub all the inner surfaces of the b
44、ucket with thesponge and then swirl the water in the bucket to rinse the innersurfaces. Discard all remaining water.8.2.7 Rinse the interior of the bucket two or more times withwater using 100 mL for each rinse.8.2.8 Fill the bucket to about 7.5 cm depth with water, coverwith a clean lid (see 8.2.11
45、 and 8.2.12) and store overnight.8.2.9 Measure the specific conductance of the water in thebucket. Transfer a portion of the rinse water to a cleanmeasuring vessel and determine the specific conductance. Ifthe specific conductance is greater than 2 S/cm (Test MethodD 1125), repeat 8.2.4-8.2.8.8.2.10
46、 Shake the inverted bucket to remove any excesswater and place the bucket in a clean plastic bag, making surethat only the interior of the bag contacts the interior of thebucket. Seal the bag with rubber bands or twist ties.8.2.11 Scrub the inner surface of the lid with the sponge.Rinse the lid with
47、 water.8.2.12 Soak the lids for at least 24 h in water.8.2.13 Rinse lids with water, shake free the excess water,and place lid in a plastic bag. Seal the bag with a rubber bandor twist tie.NOTE 3All cleaning and packaging steps should be performed whilewearing talc-free plastic gloves. Both hands sh
48、ould be gloved. Glovesshould be worn for all procedures that are used to prepare materials for thecollection and preservation of AWD.8.3 Inorganic IonsPlastic Bottles:8.3.1 Sample containers shall be made of materials that willnot contaminate the sample and shall be cleaned thoroughlybefore use. HDP
49、E is most commonly used.8.3.2 Soak the bottle closures (caps) in water while thebottles are being prepared.8.3.3 Rinse each bottle a minimum of three times withwater. The amount of water used for each rinse is dependent onthe bottle volume. For 250-mL or smaller bottles, use aboutone-half the bottle volume. For bottles larger than 250 mL, useat least 200 mL of water.8.3.4 Fill each bottle as full as possible with water and sealwith the cap. Store the full bottles at least overnight (see Note3).8.3.5 Randomly select bottles and determine the conductiv-ity of the
