1、Designation: D6866 16Standard Test Methods forDetermining the Biobased Content of Solid, Liquid, andGaseous Samples Using Radiocarbon Analysis1This standard is issued under the fixed designation D6866; the number immediately following the designation indicates the year oforiginal adoption or, in the
2、 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. Scope*1.1 This standard is a test method that teaches how toexperimentally measure biobased carb
3、on content of solids,liquids, and gaseous samples using radiocarbon analysis. Thesetest methods do not address environmental impact, productperformance and functionality, determination of geographicalorigin, or assignment of required amounts of biobased carbonnecessary for compliance with federal la
4、ws.1.2 These test methods are applicable to any product con-taining carbon-based components that can be combusted in thepresence of oxygen to produce carbon dioxide (CO2) gas. Theoverall analytical method is also applicable to gaseoussamples, including flue gases from electrical utility boilers andw
5、aste incinerators.1.3 These test methods make no attempt to teach the basicprinciples of the instrumentation used although minimumrequirements for instrument selection are referenced in theReferences section. However, the preparation of samples forthe above test methods is described. No details of i
6、nstrumentoperation are included here. These are best obtained from themanufacturer of the specific instrument in use.1.4 LimitationThis standard is applicable to laboratoriesworking without exposure to artificial carbon-14 (14C). Artifi-cial14C is routinely used in biomedical studies by both liquids
7、cintillation counter (LSC) and accelerator mass spectrometry(AMS) laboratories and can exist within the laboratory at levels1,000 times or more than 100 % biobased materials and100,000 times more than 1% biobased materials. Once in thelaboratory, artificial14C can become undetectably ubiquitouson do
8、or knobs, pens, desk tops, and other surfaces but whichmay randomly contaminate an unknown sample producinginaccurately high biobased results. Despite vigorous attemptsto clean up contaminating artificial14C from a laboratory,isolation has proven to be the only successful method ofavoidance. Complet
9、ely separate chemical laboratories andextreme measures for detection validation are required fromlaboratories exposed to artificial14C. Accepted requirementsare:(1) disclosure to clients that the laboratory(s) working withtheir products and materials also works with artificial14C(2) chemical laborat
10、ories in separate buildings for thehandling of artificial14C and biobased samples(3) separate personnel who do not enter the buildings of theother(4) no sharing of common areas such as lunch rooms andoffices(5) no sharing of supplies or chemicals between the two(6) quasi-simultaneous quality assuran
11、ce measurementswithin the detector validating the absence of contaminationwithin the detector itself. (1, 2, and 3)21.5 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
12、 safety and health practices and determine the applica-bility of regulatory limitations prior to use.NOTE 1ISO 16620-2 is equivalent to this standard.2. Referenced Documents2.1 ASTM Standards:3D883 Terminology Relating to Plastics2.2 Other Standards:4CEN/TS 16640:2014 Biobased ProductsDetermination
13、ofthe biobased carbon content of products using the radio-carbon methodCEN/TS 16137:2011 PlasticsDetermination of biobasedcarbon contentISO 16620-2:2015 PlasticsBiobased contentPart 2: De-termination of biobased carbon content1These test methods are under the jurisdiction of ASTM Committee D20 onPla
14、stics and are the direct responsibility of Subcommittee D20.96 on Environmen-tally Degradable Plastics and Biobased Products.Current edition approved June 1, 2016. Published June 2016. Originallyapproved in 2004. Last previous edition approved in 2012 as D6866 - 12. DOI:10.1520/D6866-16.2The boldfac
15、e numbers in parentheses refer to a list of references at the end ofthis standard.3For 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 pag
16、e onthe ASTM website.4Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA
17、 19428-2959. United States1EN 15440:2011 Solid recovered fuelsMethods for the de-termination of biomass contentISO 13833:2013 Stationary source emissionsDetermination of the ratio of biomass (biogenic) andfossil-derived carbon dioxideRadiocarbon samplingand determination3. Terminology3.1 The definit
18、ions of terms used in these test methods arereferenced in order that the practitioner may require furtherinformation regarding the practice of the art of isotope analysisand to facilitate performance of these test methods.3.2 Terminology D883 should be referenced for terminol-ogy relating to plastic
19、s. Although an attempt to list terms in alogical manner (alphabetically) will be made as some termsrequire definition of other terms to make sense.3.3 Definitions:3.3.1 AMS facilitya facility performing Accelerator MassSpectrometry.3.3.2 accelerator mass spectrometry (AMS)an ultra-sensitive techniqu
20、e that can be used for measuring naturallyoccurring radio nuclides, in which sample atoms are ionized,accelerated to high energies, separated on basis of momentum,charge, and mass, and individually counted in Faraday collec-tors. This high energy separation is extremely effective infiltering out iso
21、baric interferences, such thatAMS may be usedto measure accurately the14C12C abundance to a level of 1in 1015. At these levels, uncertainties are based on countingstatistics through the Poisson distribution (4,5).3.3.3 automated effciency control (AEC)a method usedby scintillation counters to compen
22、sate for the effect ofquenching on the sample spectrum (6).3.3.4 background radiationthe radiation in the naturalenvironment; including cosmic radiation and radionuclidespresent in the local environment, for example, materials ofconstruction, metals, glass, concrete (7,8,9,4,6-14).3.3.5 biobasedcont
23、aining organic carbon of renewableorigin like agricultural, plant, animal, fungi, microorganisms,marine, or forestry materials living in a natural environment inequilibrium with the atmosphere.3.3.6 biobased carbon contentthe amount of biobasedcarbon in the material or product as a percent of the to
24、talorganic carbon (TOC) in the product.3.3.7 biobased carbon content on mass basisamount ofbiobased carbon in the material or product as a percent of thetotal mass of product.3.3.8 biogeniccontaining carbon (organic and inorganic)of renewable origin like agricultural, plant, animal, fungi,microorgan
25、isms, macroorganisms, marine, or forestry materi-als.3.3.9 biogenic carbon contentthe amount of biobasedcarbon in the material or product as a percent of the totalcarbon (TC) in the product.3.3.10 biogenic carbon content on mass basisamount ofbiogenic carbon in the material or product as a percent o
26、f thetotal mass of product.3.3.11 break seal tubethe sample tube within which thesample, copper oxide, and silver wire is placed.3.3.12 coincidence circuita portion of the electronicanalysis system of an LSC which acts to reject pulses which arenot received from the two Photomultiplier Tubes (that c
27、ountthe photons) within a given period of time and are necessary torule out background interference and required for any LSCused in these test methods (9, 6, 12).3.3.13 coincidence thresholdthe minimum decay energyrequired for an LSC to detect a radioactive event. The ability toset that threshold is
28、 a requirement of any LSC used in these testmethods (6, 12).3.3.14 contemporary carbona direct indication of therelative contributions of fossil carbon and “living” biosphericcarbon can be expressed as the fraction (or percentage) ofcontemporary carbon, symbol fC. This is derived from “frac-tion of
29、modern” (fM) through the use of the observed inputfunction for atmospheric14C over recent decades, representingthe combined effects of fossil dilution of14C (minor) andnuclear testing enhancement (major). The relation between fCand fMis necessarily a function of time. By 1985, when theparticulate sa
30、mpling discussed in the cited reference wasperformed, the fMratio had decreased to approximately 1.2 (4,5).3.3.15 chemical quenchinga reduction in the scintillationintensity (a significant interference with these test methods)seen by the Photomultiplier Tubes (PMT, pmt) due to thematerials present i
31、n the scintillation solution that interfere withthe processes leading to the production of light. The result isfewer photons counted and a lower efficiency (8, 9, 12).3.3.16 chi-square testa statistical tool used in radioactivecounting in order to compare the observed variations in repeatcounts of a
32、 radioactive sample with the variation predicted bystatistical theory. This determines whether two different distri-butions of photon measurements originate from the samephotonic events. LSC instruments used in this measurementshould include this capability (6, 12, 15).3.3.17 cocktailthe solution in
33、 which samples are placedfor measurement in an LSC. Solvents and Scintillatorschemicals that absorb decay energy transferred from thesolvent and emits light (photons) proportional in intensity tothe deposited energy (8, 9, 6, 12).3.3.18 decay (radioactive)the spontaneous transformationof one nuclide
34、 into a different nuclide or into a different energystate of the same nuclide. The process results in a decrease,with time, of the number of original radioactive atoms in asample, according to the half-life of the radionuclide (4, 6, 12).3.3.19 discriminatoran electronic circuit which distin-guishes
35、 signal pulses according to their pulse height or energy;used to exclude extraneous radiation, background radiation,and extraneous noise from the desired signal (6, 12, 13, 16).3.3.20 dpmdisintegrations per minute. This is the quantityof radioactivity. The measure dpm is derived from cpm orcounts pe
36、r minute (dpm = cpm bkgd / counting efficiency).There are 2.2 106dpm / Ci (6, 12).D6866 1623.3.21 dpsdisintegrations per second (rather than minuteas above) (6, 12).3.3.22 effciencythe ratio of measured observations orcounts compared to the number of decay events which oc-curred during the measureme
37、nt time; expressed as a percentage(6, 12).3.3.23 external standarda radioactive source placed adja-cent to the liquid sample to produce scintillations in the samplefor the purpose of monitoring the samples level of quenching(6, 12).3.3.24 figure of merita term applied to a numerical valueused to cha
38、racterize the performance of a system. In liquidscintillation counting, specific formulas have been derived forquantitatively comparing certain aspects of instrument andcocktail performance and the term is frequently used tocompare efficiency and background measures (6, 12, 17).3.3.25 flexible tube
39、crackerthe apparatus in which thesample tube (Break Seal Tube) is placed (18, 19, 20, 21).3.3.26 fluorescencethe emission of light resulting fromthe absorption of incident radiation and persisting only as longas the stimulation radiation is continued (6, 12, 22).3.3.27 fossil carboncarbon that conta
40、ins essentially noradiocarbon because its age is very much greater than the 5,730year half-life of14C (4, 5).3.3.28 half-lifethe time in which one half the atoms of aparticular radioactive substance disintegrate to another nuclearform. The half-life of14C is 5,730 years (4, 6, 22).3.3.29 intensityth
41、e amount of energy, the number ofphotons, or the numbers of particles of any radiation incidentupon a unit area per unit time (6, 12).3.3.30 internal standarda known amount of radioactivitywhich is added to a sample in order to determine the countingefficiency of that sample. The radionuclide used m
42、ust be thesame as that in the sample to be measured, the cocktail shouldbe the same as the sample, and the Internal Standard must beof certified activity (6, 12).3.3.31 modern carbonexplicitly, 0.95 times the specificactivity of SRM 4990B (the original oxalic acid radiocarbonstandard), normalized to
43、 13C = 19 % (Currie, et al., 1989).Functionally, the fraction of modern carbon equals 0.95 timesthe concentration of14C contemporaneous with 1950 wood(that is, pre-atmospheric nuclear testing). To correct for thepost 1950 bomb14C injection into the atmosphere (5), thefraction of modern carbon is mul
44、tiplied by a correction factorrepresentative of the excess14C in the atmosphere at the timeof measurements.3.3.32 noise pulsea spurious signal arising from the elec-tronics and electrical supply of the instrument (6, 12, 23, 24).3.3.33 phase contactthe degree of contact between twophases of heteroge
45、neous samples. In liquid scintillationcounting, better phase contact usually means higher countingefficiency (6, 12).3.3.34 photomultiplier tube (PMT, pmt)the device in theLSC that counts the photons of light simultaneously at twoseparate detectors (24, 16).3.3.35 pulsethe electrical signal resultin
46、g when photonsare detected by the PMTs (6, 12, 13, 16).3.3.36 pulse height analyzer (PHA)an electronic circuitwhich sorts and records pulses according to height or voltage(6, 12, 13, 16).3.3.37 pulse indexthe number of after-pulses following adetected coincidence pulse (used in three dimensional or
47、pulseheight discrimination) to compensate for the background of anLSC performing (6, 13, 24, 16).3.3.38 quenchingany material that interferes with theaccurate conversion of decay energy to photons captured by thePMT of the LSC (7, 8, 9, 6, 10, 12, 17).3.3.39 regionregions of interest, also called wi
48、ndowand/or channel in regard to LSC. Refers to an energy level orsubset specific to a particular isotope (8, 6, 13, 23, 24).3.3.40 renewablebeing readily replaced and of non-fossilorigin; specifically not of petroleum origin.3.3.41 scintillationthe sum of all photons produced by aradioactive decay e
49、vent. Counters used to measure this asdescribed in these test methods are Liquid Scintillation Coun-ters (LSC) (6, 12).3.3.42 scintillation reagentchemicals that absorbs decayenergy transferred from the solvent and emits light (photons)proportional in intensity to the decay energy (8, 6, 24).3.3.43 solvent-in scintillation reagentchemical(s) whichact as both a vehicle for dissolving the sample and scintillatorand the location of the initial kinetic energy transfer from thedecay products to the scintillator; that is, into
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