1、Designation: D5012 01 (Reapproved 2013)Standard Guide forPreparation of Materials Used for the Collection andPreservation of Atmospheric Wet Deposition1This standard is issued under the fixed designation D5012; the number immediately following the designation indicates the year oforiginal adoption o
2、r, 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 guide presents recommendations for the cleaningof plastic or glass materi
3、als used for collection 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 po
4、lyethylene (HDPE) 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 isrecommende
5、d for samples for the determination of otherorganic compounds.1.3 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is th
6、eresponsibility 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. Referenced Documents2.1 ASTM Standards:2D883 Terminology Relating to PlasticsD1125 Test Methods for Electrical Conductivity an
7、d Resis-tivity of WaterD1129 Terminology Relating to WaterD1193 Specification for Reagent WaterD1356 Terminology Relating to Sampling and Analysis ofAtmospheresD1695 Terminology of Cellulose and Cellulose DerivativesD2914 Test Methods for Sulfur Dioxide Content of theAtmosphere (West-Gaeke Method)D4
8、453 Practice for Handling of High Purity Water Samples3. Terminology3.1 Definitions:3.1.1 For definitions of terms used in this guide, refer toTerminology D1129.3.1.2 For definition of plastic refer to Terminology D1695and Terminology D883.3.1.3 For definition of AWD (precipitation, meteorologi-cal)
9、 refer to Terminology D1356.4. Significance and Use4.1 Some chemical constituents of AWD are not stable andmust be preserved before chemical analysis. Without samplepreservation, it is possible that analytes can be lost throughdecomposition or sorption to the storage bottles.4.2 Contamination of AWD
10、 samples can occur during bothsample preservation and sample storage. Proper selection andcleaning of sampling containers are required 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
11、potentialsources of contamination. Individual experience should beused to select products that minimize contamination.5. Apparatus5.1 Instruments shall be selected in accordance with anapplicable test method given in Test Methods D1125.5.2 The conductivity cell shall be pipet or dip type with acell
12、constant (K) of 0.1.6. Reagents and Materials6.1 Purity of ReagentsReagent grade acids and otherchemicals shall be used to reduce the risk of contaminating theAWD samples. Unless otherwise indicated, it is intended thatall reagents conform to the specifications of the Committee on1This guide is unde
13、r the jurisdiction of ASTM Committee D22 on Air Qualityand is the direct responsibility of Subcommittee D22.03 on Ambient Atmospheresand Source Emissions.Current edition approved Oct. 1, 2013. Published October 2013. Originallyapproved in 1989. Last previous edition approved in 2008 as D5012 - 01 (2
14、008).DOI: 10.1520/D5012-01R13.2For referenced ASTM standards, visit the ASTM 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.Copyright ASTM International, 1
15、00 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1Analytical Reagents of the American Chemical Society wheresuch specifications are available.36.2 Nitric acid, ultra pure.6.3 Nitric acid (1+9)Dilute 1 volume concentrated nitricacid with 9 volumes of water.6.4 Chlorof
16、orm, high performance liquid chromatographyreagent.6.5 Hydrochloric acid, pretested 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 D1193. AWD samples collected fororganic a
17、nalysis may require Type II (distilled) reagent water.7. Sample Preservation7.1 Interaction 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 conce
18、ntration levelsof their analytes. Trace metals, and possibly other ions inAWDsamples, 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
19、of AWDsamples is best and chemical preservation should be used onlywhen the preservation 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) (1
20、and2).47.2 Samples Collected for Inorganic Cation and AnionDeterminations:7.2.1 Samples collected for pH, specific conductance,calcium, magnesium, potassium, sodium, chloride, fluoride,and sulfate analysis are often only placed in pre-cleaned plasticcontainers (see Section 8) before analysis. If the
21、re is a delaybetween time of collection and time of analysis, a preservationtechnique 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
22、collected for the analysis of acetate, citrate,formate and other low molecular 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 (12-18). These compounds (inparticular formi
23、c and acetic acids) can constitute from a smallfraction to mostly all of the free acidity in AWD samples.Because these acids are unstable in AWD samples, samplesmust be analyzed within hours after collection or else apreservation technique is required. Table 2 summarizes therecommended sample preser
24、vation techniques for AWDsamples.7.4 Samples Collected for Trace Dissolved Metals:7.4.1 Samples collected for trace 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.
25、 Filter materialsmay contain trace elements, and the filters should be precon-ditioned before use by filtering 300 mL of water in order toleach soluble impurities on the filter and from the filtrationapparatus itself (19). Any filters used for AWD samples shouldbe tested to determine if the filter c
26、auses losses or gains of traceelements to theAWD sample. Test the preconditioned filters byfiltering 50 mL of water 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 highestp
27、urity acid available should be used. Most AWD samples arepoorly buffered and only small quantities of acid (about 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.3Reagent Chemicals, American C
28、hemical Society Specifications , AmericanChemical Society, Washington, DC. For 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
29、. Pharmaceutical Convention, Inc. (USPC), Rockville,MD.4The boldface numbers in parentheses refer to the list of references at the end ofthis standard.TABLE 1 Preservation of AWD Samples Collected for Inorganic Cation and Anion DeterminationsPreservation Technique Species Determined Remarks Referenc
30、eNo preservation All inorganic cations and anions Rapid analysis is required after collection because ion concentrations maychange in samples. Ammonium, nitrate, and ortho-phosphate concentrationsmay be reduced in samples that are biologically active. Cation and trace metalconcentrations may be redu
31、ced by sorption onto container surfaces.(3-7)Refrigerate 4C All inorganic cations and anions Chilling may reduce the loss of ammonium, nitrate, and ortho-phosphate insamples that are biologically active. Samples must be allowed to come to am-bient temperature (2327C) before performing pH and specifi
32、c conductancedeterminations. Specific conductance and pH determinations should be per-formed on-site as soon as possible after sample collection.(8-10)HNO3pH # 2Ca2+,Mg2+,Na+,K+Samples must first be filtered, or acid addition may dissolve particles in the AWDsamples (see 7.4.1). Acid addition will i
33、nterfere with anion determination, so aseparate aliquot will be needed for other ion determinations.(4,5)HCl, 5 mL/L All dissolved Hg and total Hg Samples for dissolved Hg are filtered through 0.45 m capsule filter. Samplescollected directly into specially cleaned, pretested, fluoropolymer bottle.(1
34、,2)Filtration All inorganic cations and anions pH and specific conductance determinations may be affected by filtration. Caremust be taken to minimize the possibility of sample contamination during filtra-tion.(11)D5012 01 (2013)27.4.3 Acidify the AWD sample with 5 mL/L of pretestedHCl for dissolved
35、 mercury and total mercury.8. Sample Containers8.1 ManyAWD sampling networks 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 atm
36、osphere during the precipitation event. Thepreparation or cleaning procedures 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
37、 a cleaning procedure for AWD samplingthat uses a bottle as the principal 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
38、 contaminate the sample and shall be cleaned thoroughlybefore use. Plastic containers of polyethylene and polypropyl-ene 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 bucke
39、ts and lids only with water. Theinside of the bucket and inner side of the 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 naturalspong
40、es requires that the sponge is washed with copious amounts of waterat least 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 1
41、000 mL of water in the bucket.8.2.6 Scrub all the inner surfaces of the bucket 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 b
42、ucket to about 7.5 cm depth with water, coverwith a clean lid (see 8.2.11 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 conducta
43、nce is greater than 2 S/cm (Test MethodD1125), repeat 8.2.4 8.2.8.8.2.10 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.
44、11 Scrub the inner surface of the lid with the sponge.Rinse the lid with 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
45、should be performed whilewearing talc-free plastic gloves. Both hands should 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 willn
46、ot contaminate the sample and shall be cleaned thoroughlybefore use. HDPE 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 bo
47、ttle 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
48、 and determine the conductiv-ity of the bottle contents. If there is more than one bottle witha conductivity greater than 2 S/cm, the bottles should berewashed.8.3.6 Slowly drain the water from the bottles, shake free anyexcess water, and recap the bottles immediately.8.3.7 The bottle soak solution
49、should be analyzed for theions of interest on a regular basis and each time a new supplyof plastic bottles is obtained.8.4 Trace ElementsPlastic Bottles:TABLE 2 Preservation of AWD Samples Collected for Organic Acid DeterminationsPreservation Technique Species Determined Remarks ReferenceChloroform Acetate, citrate, formate, C1C5Analysis 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
