1、Designation: D4638 11Standard Guide forPreparation of Biological Samples for Inorganic ChemicalAnalysis1This standard is issued under the fixed designation D4638; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last rev
2、ision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This guide describes procedures for the preparation oftest samples collected from such locations as streams, rivers,ponds, la
3、kes, estuaries, oceans, and toxicity tests and isapplicable to such organisms as plankton, mollusks, fish, andplants.1.2 The procedures are applicable to the determination ofvolatile, semivolatile, and nonvolatile inorganic constituents ofbiological materials. Analyses may be carried out or reported
4、on either a dry or wet basis.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 theresponsibility of the user of th
5、is standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. For a specifichazard statement, see 9.3.3.2. Referenced Documents2.1 ASTM Standards:2D1129 Terminology Relating to WaterD1193 Specification for Reagent Water3. T
6、erminology3.1 DefinitionsFor definitions of terms used in this guide,refer to Terminology D1129.4. Summary of Guide4.1 Samples are collected, where possible, with nonmetallicor TFE-fluorocarbon-coated sampling equipment to preventcontamination, stored in plastic containers, and kept either at4C or f
7、rozen until returned to an adequate facility for analysis.4.2 Before analysis, samples are allowed to return to roomtemperature. Large foreign objects are mechanically removedfrom the samples based upon visual examination; smallerforeign objects are also removed mechanically, with the aid ofa low-po
8、wer microscope.4.3 Wet samples of small organisms such as plankton, aremixed for preliminary homogenization, then allowed to settle,to remove most of the occluded water. Larger organisms, suchas fish, should be patted dry, using paper towels.4.4 Where less than a whole organism is to be analyzed,tis
9、sue excisions are made with nonmetallic tools such as plasticknives or TFE-fluorocarbon-coated scalpels.4.5 Moisture determinations are made on separate samplesfrom those analyzed for volatile or semivolatile constituents.4.6 Analyses for volatile constituents are made using wetsamples from which su
10、pernatant liquid or occluded water hasbeen removed (see 4.3). The results may be calculated to thedry, original-sample basis, using the results of a moisturedetermination carried out on a separate sample.4.7 Analyses for semivolatile constituents are made on wetsamples or samples previously dried at
11、 a temperature (depen-dent on constituents of interest), or using a procedure, found tobe adequate for the purpose, and specified in the correspondinganalytical procedure.4.8 Analyses for nonvolatile constituents are made onsamples previously dried at a temperature (dependent onconstituents of inter
12、est), or using a procedure found to beadequate for the purpose, and specified in the correspondinganalytical procedure.4.9 Digest the samples according to the procedures outlinedin Section 9.4.10 A flow diagram outlining typical procedures is shownin Fig. 1.1This guide is under the jurisdiction of A
13、STM Committee D19 on Water and isthe direct responsibility of Subcommittee D19.05 on Inorganic Constituents inWater.Current edition approved Sept. 1, 2011. Published September 2011. Originallyapproved in 1986. Last previous edition approved in 2007 as D4638 03(07). DOI:10.1520/D4638-11.2For referenc
14、ed 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.1*A Summary of Changes section appears at the end of this standard.Copyrig
15、ht ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5. Significance and Use5.1 The chemical analysis of biological material, collectedfrom such locations as streams, rivers, lakes, and oceans canprovide information of environmental significance.
16、 The chemi-cal analysis of biological material used in toxicity tests may beuseful to better interpret the toxicological results.5.2 Many aquatic biological samples, either as a result oftheir size, or their method of collection, are inherently hetero-geneous in that they may contain occluded water
17、in varyingand unpredictable amounts and may contain foreign objects ormaterial (for example, sediment) not ordinarily intended foranalysis, the inclusion of which would result in inaccurateanalysis.5.3 Standard methods for separating foreign objects, tofacilitate homogenization, will minimize errors
18、 due to poormixing and inclusion of extraneous material.5.4 Standardized procedures for drying provide a means forreporting analytical values to a common dry weight basis, ifdesired. Analyses may also be carried out or reported on a wetweight basis.6. Preliminary Treatment of Samples6.1 Treat small
19、heterogeneous samples, such as plankton, asfollows:6.1.1 Allow for the sample to return to room temperature.6.1.2 Remove foreign objects, such as leaves and twigs,mechanically, using nonmetallic instruments. Use a low-powermicroscope to facilitate removal of smaller foreign objectssuch as paint chip
20、s.6.1.3 Transfer the sample to a beaker and thoroughly mix itwith a glass stirring rod or equivalent, and allow it to settle sothat most or all of the occluded water can be decanted.6.1.4 If chemical analyses are to be carried out on a wetsample, and a large amount of material is available, remove a
21、number of small portions (at least five) from random locationsin the beaker, and composite them to obtain a representativesample of a size sufficient for chemical analysis and a separatemoisture determination. Using a tissue disrupter, blender, orequivalent, homogenize the sample or composite (to en
22、surelack of contamination, carry a standard or blank, or both,through this procedure). Remove a subsample for moisturedetermination and proceed to Section 7. Retain the remainderand proceed to Section 9.6.1.5 If chemical analyses are to be carried out on a drysample, and a large amount of material i
23、s available, remove anumber of small portions (at least five) from random locationsin the beaker, and composite them to obtain a representativesample of a size sufficient for the analysis. Using a tissuedisrupter, blender, or equivalent, homogenize the sample, orcomposite (to ensure lack of contamin
24、ation, carry a standard orblank, or both, through this procedure), and proceed to Section7.FIG. 1 Flow Diagram for the Preparation of Biological Samples for Inorganic AnalysisD4638 1126.2 Treat large samples such as fish as follows:6.2.1 Allow the sample to return to room temperature.6.2.2 Pat the s
25、ample dry with paper toweling to remove asmuch water as possible.6.2.3 Transfer the sample to a nonmetallic surface, such asa flat glass plate, and excise a sufficient quantity of material, orspecific organs, to obtain sufficient material for analysis. Makeexcisions with plastic knives or TFE-fluoro
26、carbon-coated scal-pels.6.2.4 If chemical analyses are to be carried out on a wetsample, use a tissue disrupter, blender, or equivalent, tohomogenize the material (to ensure lack of contamination,carry a standard or blank, or both, through this procedure).Remove a subsample for moisture determinatio
27、n and proceedto Section 7. Retain the remainder and proceed to Section 9.6.2.5 If chemical analyses are to be carried out on a drysample, use a tissue disrupter, blender, or equivalent, tohomogenize the material (to ensure lack of contamination,carry a standard or blank, or both, through this proced
28、ure) andproceed to Section 7.7. Drying Procedures7.1 Use a sample or subsample prepared in accordance withthe directions given in Section 6.7.2 Treat subsamples from biological materials that are toundergo chemical analysis without drying for moisture deter-minations as follows:7.2.1 Accurately weig
29、h 5 to 10 g 6 1mgor10to25g610 mg of material into a nonmetallic container which has beenpreviously tared, and weighed with the same accuracy.7.2.2 When a limited amount of material is available,determine the moisture ona1to2-gsample, and weigh with anaccuracy of 60.1 mg. The use of samples smaller t
30、han 1 g isnot recommended for moisture determination.7.3 When an entire sample is to be dried prior to chemicalanalysis, a moisture determination is also required. Transfer theaccurately weighed material (1 to 2 g 6 0.1mg,5to10g61 mg, 10 g 6 10 mg) into a dry nonmetallic container whichhas been prev
31、iously tared, and weigh with the same accuracy.7.4 If a moisture determination (or sample drying) is to bemade using an oven, treat as follows:7.4.1 Transfer the containers holding the material to an ovenanddryfor2hatoneofthefollowing temperatures:7.4.1.1 For the determination of semivolatile consti
32、tuents,use the temperature specified in the analytical procedure for theconstituents(s).7.4.1.2 For determination of nonvolatile constituents use105 6 2C.7.4.2 Cool in a desiccator, then weigh the dried sampleswith the same accuracy as the wet samples.NOTE 1Biological materials tend to be very hygro
33、scopic. Keepweighing times to a minimum.7.4.3 Repeat drying at hourly intervals, to attain a constantweight.7.5 If a moisture determination (or sample drying) is to bemade at room temperature, treat as follows:7.5.1 If drying is to be done in a desiccator, ensure that thedesiccant in the bottom is f
34、resh, and some means is available toindicate when the desiccant loses its drying capacity (forexample, color change). A vacuum desiccator may also beused.NOTE 2If a vacuum desiccator is used, bear in mind that this maycause the loss of volatile or semivolatile inorganics such as mercury, if thedried
35、 sample is to be subjected to chemical analysis.7.5.1.1 Transfer the containers holding the material to adesiccator.7.5.1.2 Leave the material in the desiccator for 48 h, thenweigh the dried samples with the same accuracy as the wetsample.7.5.1.3 Repeat weighings at 4-h intervals, to attain a con-st
36、ant weight (see Note 1).7.5.2 Alternatively, sample drying or moisture determina-tions may be carried out in a laminar flow hood; treat asfollows:7.5.2.1 Transfer the containers holding the material to anappropriate hood and turn it on.7.5.2.2 Leave the material in the hood for 48 h, then weighthe d
37、ried samples with the same accuracy as the wet sample.7.5.2.3 Repeat weighings at 4-h intervals, to attain a con-stant weight (see Note 1).NOTE 3Air-drying in the open is strongly discouraged unless it iscarried out in a clean room, where possible contamination from airborneparticulates can be contr
38、olled.7.6 If a moisture determination (or sample drying) is to bemade using a freeze dryer, treat the determination as follows:7.6.1 Transfer the containers holding the material to thefreeze dryer.7.6.2 Follow the manufacturers instructions for the particu-lar unit in use. Make certain that a trap i
39、s placed between thevacuum pump and the drying chamber to prevent pump oilfumes from possibly contaminating the sample. Drying isusually complete when the internal pressure in the dryingchamber reaches 50 millitorrs or less.7.6.3 Transfer the freeze-dried samples to a desiccator forstorage, and weig
40、h them with the same accuracy as the wetsamples (see Note 1).NOTE 4Because freeze drying occurs under vacuum, this may causethe loss of volatile or semivolatile inorganics such as mercury, or both, ifthe dried sample is to be subjected to chemical analysis.7.7 The possibility of loss of volatile con
41、stituents dictatesthe drying procedure to be used, prior to chemical analysis.Determine volatile constituents using undried samples. Deter-mine semivolatile constituents using samples dried at a tem-perature at which no significant losses occur.7.8 Analytical data reported on a dry weight basis shou
42、ldinclude percent moisture so that wet weight values can beobtained. Likewise, wet weight analytical data should includepercent moisture to permit recalculation to a dry weight basis.7.9 Use the following equations to calculate percent mois-ture and to correct analytical results from samples analyze
43、dwhen wet.7.9.1 Calculate percent moisture as follows:moisture, % 5 Ww/Wd!100 (1)where:D4638 113Ww= wet weight, g, andWd= dry weight, g7.9.2 To calculate concentrations on a dry weight basis,when determinations have been made on an undried sample,use the following equation:Cd5Cw100!100 2 % moisture(
44、2)where:Cd= concentration on a dry weight basis, andCw= concentration on a wet weight basis.8. Reagents8.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents conform to the specifications of the Committee onAnalytical Reag
45、ents of the American Chemical Society wheresuch specifications are available.3Other grades may be used,provided it is first ascertained that the reagent is of sufficientlyhigh purity to permit its use without lessening the accuracy ofthe determination.8.2 Purity of WaterUnless otherwise indicated, r
46、eferencesto water shall be understood to mean reagent water conformingto Specification D1193, Type I. Other reagent water types maybe used, provided it is first ascertained that the water is ofsufficiently high purity to permit its use without adverselyaffecting the bias and precision of the test me
47、thod. Type IIwater was specified at the time of round robin testing of thismethod.8.3 All of the following reagents may not be required for aparticular procedure. Check the digestion procedure(s) ofinterest (Section 9) prior to preparing any reagents.8.3.1 Amyl Alcohol.8.3.2 Hydrochloric Acid (1+1)M
48、ix one volume of hydro-chloric acid (HCl, sp gr 1.19) with one volume of water.8.3.3 Hydrogen Peroxide Solution (30 % H2O2w/v)Commercially available.8.3.4 Magnesium Nitrate Solution (7 g/L)Dissolve7gofmagnesium nitrate Mg(NO3)26H2O in water and dilute to1000 mL.8.3.5 Nitric Acid (sp gr 1.42)Concentr
49、ated ultra-purenitric acid (HNO3).8.3.6 Nitric Acid (1+9)Mix one volume of nitric acid(HNO3, sp gr 1.42) with nine volumes of water.8.3.7 Nitric-Perchloric Acid Solution (3+1)Mix threevolumes of ultra-pure concentrated nitric acid (HNO3,spgr1.42) with one volume of ultrapure concentrated perchloricacid (HClO4, sp gr 1.67).8.3.8 Sulfuric Acid (sp gr 1.84)Concentrated ultra-puresulfuric acid (H2SO4).8.3.9 Sulfuric Acid (1+9)Mix one volume of sulfuric acid(H2SO4, sp gr 1.84) with nine volumes of water.9. Digestion Procedures9.1 Many procedures are available for t
