1、Designation: D6866 16D6866 18Standard 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
2、, 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. Scope*1.1 This standard is a test method that teaches how to experimentally measure biob
3、ased carbon content of solids, liquids, andgaseous samples using radiocarbon analysis. These test methods do not address environmental impact, product performance andfunctionality, determination of geographical origin, or assignment of required amounts of biobased carbon necessary forcompliance with
4、 federal laws.1.2 These test methods are applicable to any product containing carbon-based components that can be combusted in thepresence of oxygen to produce carbon dioxide (CO2) gas. The overall analytical method is also applicable to gaseous samples,including flue gases from electrical utility b
5、oilers and waste incinerators.1.3 These test methods make no attempt to teach the basic principles of the instrumentation used although minimumrequirements for instrument selection are referenced in the References section. However, the preparation of samples for the abovetest methods is described. N
6、o details of instrument operation are included here. These are best obtained from the manufacturer ofthe specific instrument in use.1.4 LimitationThis standard is applicable to laboratories working without exposure to artificial carbon-14 (14C).Artificial 14Cis routinely used in biomedical studies b
7、y both liquid scintillation counter (LSC) and accelerator mass spectrometry (AMS)laboratories and can exist within the laboratory at levels 1,000 times or more than 100 % biobased materials and 100,000 timesmore than 1% biobased materials. Once in the laboratory, artificial 14C can become undetectab
8、ly ubiquitous on door knobs, pens,desk tops, and other surfaces but which may randomly contaminate an unknown sample producing inaccurately high biobasedresults. Despite vigorous attempts to clean up contaminating artificial 14C from a laboratory, isolation has proven to be the onlysuccessful method
9、 of avoidance. Completely separate chemical laboratories and extreme measures for detection validation arerequired from laboratories exposed to artificial 14C. Accepted requirements are:(1) disclosure to clients that the laboratory(s) working with their products and materials also works with artific
10、ial 14C(2) chemical laboratories in separate buildings for the handling of artificial 14C and biobased samples(3) separate personnel who do not enter the buildings of the other(4) no sharing of common areas such as lunch rooms and offices(5) no sharing of supplies or chemicals between the two(6) qua
11、si-simultaneous quality assurance measurements within the detector validating the absence of contamination within thedetector itself. (1, 2, and 3)21.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this s
12、tandard to establish appropriate safety safety, health, and healthenvironmental practices and determine theapplicability of regulatory limitations prior to use.NOTE 1ISO 16620-2 is equivalent to this standard.1.6 This international standard was developed in accordance with internationally recognized
13、 principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.1 These test methods are under the jurisdiction of ASTM Committee D20 o
14、n Plastics and are the direct responsibility of Subcommittee D20.96 on EnvironmentallyDegradable Plastics and Biobased Products.Current edition approved June 1, 2016March 1, 2018. Published June 2016March 2018. Originally approved in 2004. Last previous edition approved in 20122016 asD6866 - 12.D686
15、6 - 16. DOI: 10.1520/D6866-16.10.1520/D6866-18.2 The boldface numbers in parentheses refer to a list of references at the end of this standard.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previo
16、us version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Chang
17、es section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States12. Referenced Documents2.1 ASTM Standards:3D883 Terminology Relating to Plastics2.2 Other Standards:4CEN/TS 16640:2014 Biobased ProductsDete
18、rmination of the biobased carbon content of products using the radiocarbonmethodCEN/TS 16137:2011 PlasticsDetermination of biobased carbon contentISO 16620-2:2015 PlasticsBiobased contentPart 2: Determination of biobased carbon contentEN 15440:2011 Solid recovered fuelsMethods for the determination
19、of biomass contentISO 13833:2013 Stationary source emissionsDetermination of the ratio of biomass (biogenic) and fossil-derived carbondioxideRadiocarbon sampling and determination3. Terminology3.1 The definitions of terms used in these test methods are referenced in order that the practitioner may r
20、equire furtherinformation regarding the practice of the art of isotope analysis and to facilitate performance of these test methods.3.2 Terminology D883 should be referenced for terminology relating to plastics. Although an attempt to list terms in a logicalmanner (alphabetically) will be made as so
21、me terms require definition of other terms to make sense.3.3 Definitions:3.3.1 AMS facilitya facility performing Accelerator Mass Spectrometry.3.3.2 accelerator mass spectrometry (AMS)an ultra-sensitive technique that can be used for measuring naturally occurringradio nuclides, in which sample atoms
22、 are ionized, accelerated to high energies, separated on basis of momentum, charge, andmass, and individually counted in Faraday collectors. This high energy separation is extremely effective in filtering out isobaricinterferences, such that AMS may be used to measure accurately the 14C 12C abundanc
23、e to a level of 1 in 1015. At these levels,uncertainties are based on counting statistics through the Poisson distribution (4,5).3.3.3 automated effciency control (AEC)a method used by scintillation counters to compensate for the effect of quenching onthe sample spectrum (6).3.3.4 background radiati
24、onthe radiation in the natural environment; including cosmic radiation and radionuclides present inthe local environment, for example, materials of construction, metals, glass, concrete (7,8,9,4,6-14).3.3.5 biobasedcontaining organic carbon of renewable origin like agricultural, plant, animal, fungi
25、, microorganisms, marine,or forestry materials living in a natural environment in equilibrium with the atmosphere.3.3.6 biogeniccontaining carbon (organic and inorganic) of renewable origin like agricultural, plant, animal, fungi,microorganisms, macroorganisms, marine, or forestry materials.3.3.7 bi
26、obased carbon contentthe amount of biobased carbon in the material or product as a percent of the total organic carbon(TOC) in the product.3.3.8 biobased carbon content on mass basisbiogenic carbon contentthe amount of biobasedbiogenic carbon in the materialor product as a percent of the total mass
27、of carbon (TC) in the product.3.3.8 biogeniccontaining carbon (organic and inorganic) of renewable origin like agricultural, plant, animal, fungi,microorganisms, macroorganisms, marine, or forestry materials.3.3.9 biogenic carbon contentbiobased carbon content on mass basisthe amount of biobased car
28、bon in the material orproduct as a percent of the total carbon (TC) in the mass of product.3.3.10 biogenic carbon content on mass basisamount of biogenic carbon in the material or product as a percent of the totalmass of product.3.3.11 break seal tubethe sample tube within which the sample, copper o
29、xide, and silver wire is placed.3.3.12 coincidence circuita portion of the electronic analysis system of an LSC which acts to reject pulses which are notreceived from the two Photomultiplier Tubes (that count the photons) within a given period of time and are necessary to rule outbackground interfer
30、ence and required for any LSC used in these test methods (9, 6, 12).3.3.13 coincidence thresholdthe minimum decay energy required for an LSC to detect a radioactive event. The ability to setthat threshold is a requirement of any LSC used in these test methods (6, 12).3.3.14 contemporary carbona dire
31、ct indication of the relative contributions of fossil carbon and “living” biospheric carboncan be expressed as the fraction (or percentage) of contemporary carbon, symbol fC. This is derived from “fraction of modern”3 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM
32、Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.4 Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http:/www.ansi.org.D6866 182(fM) th
33、rough the use of the observed input function for atmospheric 14C over recent decades, representing the combined effects offossil dilution of 14C (minor) and nuclear testing enhancement (major). The relation between fC and fM is necessarily a functionof time. By 1985, when the particulate sampling di
34、scussed in the cited reference was performed, the fM ratio had decreased toapproximately 1.2 (4, 5).3.3.15 chemical quenchinga reduction in the scintillation intensity (a significant interference with these test methods) seen bythe Photomultiplier Tubes (PMT, pmt) due to the materials present in the
35、 scintillation solution that interfere with the processesleading to the production of light. The result is fewer photons counted and a lower efficiency (8, 9, 12).3.3.16 chi-square testa statistical tool used in radioactive counting in order to compare the observed variations in repeatcounts of a ra
36、dioactive sample with the variation predicted by statistical theory. This determines whether two different distributionsof photon measurements originate from the same photonic events. LSC instruments used in this measurement should include thiscapability (6, 12, 15).3.3.17 cocktailthe solution in wh
37、ich samples are placed for measurement in an LSC. Solvents and Scintillatorschemicalsthat absorb decay energy transferred from the solvent and emits light (photons) proportional in intensity to the deposited energy(8, 9, 6, 12).3.3.18 decay (radioactive)the spontaneous transformation of one nuclide
38、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 a sample,according to the half-life of the radionuclide (4, 6, 12).3.3.19 discriminatoran electronic circuit which distinguishes
39、signal pulses according to their pulse height or energy; used toexclude extraneous radiation, background radiation, and extraneous noise from the desired signal (6, 12, 13, 16).3.3.20 dpmdisintegrations per minute. This is the quantity of radioactivity. The measure dpm is derived from cpm or countsp
40、er minute (dpm = cpm bkgd / counting efficiency). There are 2.2 106 dpm / Ci (6, 12).3.3.21 dpsdisintegrations per second (rather than minute as above) (6, 12).3.3.22 effciencythe ratio of measured observations or counts compared to the number of decay events which occurred duringthe measurement tim
41、e; expressed as a percentage (6, 12).3.3.23 external standarda radioactive source placed adjacent to the liquid sample to produce scintillations in the sample forthe purpose of monitoring the samples level of quenching (6, 12).3.3.24 figure of merita term applied to a numerical value used to charact
42、erize the performance of a system. In liquidscintillation counting, specific formulas have been derived for quantitatively comparing certain aspects of instrument and cocktailperformance and the term is frequently used to compare efficiency and background measures (6, 12, 17).3.3.25 flexible tube cr
43、ackerthe apparatus in which the sample tube (Break Seal Tube) is placed (18, 19, 20, 21).3.3.26 fluorescencethe emission of light resulting from the absorption of incident radiation and persisting only as long as thestimulation radiation is continued (6, 12, 22).3.3.27 fossil carboncarbon that conta
44、ins essentially no radiocarbon because its age is very much greater than the 5,730 yearhalf-life of 14C (4, 5).3.3.28 half-lifethe time in which one half the atoms of a particular radioactive substance disintegrate to another nuclear form.The half-life of 14C is 5,730 years (4, 6, 22).3.3.29 intensi
45、tythe amount of energy, the number of photons, or the numbers of particles of any radiation incident upon a unitarea per unit time (6, 12).3.3.30 internal standarda known amount of radioactivity which is added to a sample in order to determine the countingefficiency of that sample. The radionuclide
46、used must be the same as that in the sample to be measured, the cocktail should be thesame as the sample, and the Internal Standard must be of certified activity (6, 12).3.3.31 modern carbonexplicitly, 0.95 times the specific activity of SRM 4990B (the original oxalic acid radiocarbonstandard), norm
47、alized to 13C = 19 % (Currie, et al., 1989). Functionally, the fraction of modern carbon equals 0.95 times theconcentration of 14C contemporaneous with 1950 wood (that is, pre-atmospheric nuclear testing). To correct for the post 1950bomb 14C injection into the atmosphere (5), the fraction of modern
48、 carbon is multiplied by a correction factor representative ofthe excess 14C in the atmosphere at the time of measurements.3.3.32 noise pulsea spurious signal arising from the electronics and electrical supply of the instrument (6, 12, 23, 24).3.3.33 phase contactthe degree of contact between two ph
49、ases of heterogeneous samples. In liquid scintillation counting,better phase contact usually means higher counting efficiency (6, 12).3.3.34 photomultiplier tube (PMT, pmt)the device in the LSC that counts the photons of light simultaneously at two separatedetectors (24, 16).3.3.35 pulsethe electrical signal resulting when photons are detected by the PMTs (6, 12, 13, 16).D6866 1833.3.36 pulse height analyzer (PHA)an electronic circuit which sorts and records pulses according to height or voltage (6, 12,13, 16).3.3.37 pu
