ASTM E1757 − 19

Designation: E1757 19 Standard Practice for Preparation of Biomass for Compositional Analysis 1 This standard is issued under the ﬁxed designation E1757; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A superscript epsilon (´) indicates an editorial change since the last revision or reapproval. 1. Scope 1.1 This practice covers a reproducible way to convert hardwoods, softwoods, herbaceous materials (such as switch- grass and sericea), agricultural residues (such as corn stover, wheat straw, and bagasse), wastepaper (such as office waste, boxboard, and newsprint), cellulosic feedstocks pretreated to improve suitability for fermentation, cereal grains, cereal grain fermentationmash,cerealgrainfermentationbeer,andfermen- tation residues into a uniform material suitable for composi- tional analysis. This practice is intended for samples that need to be dried prior to analysis. 1.2 Milling and sieving actions both produce large amounts of dust. This dust can be a nuisance hazard and irritant. Use appropriate respiratory protection as needed. If excessive amounts of dust are allowed to become airborne a potential explosion hazard is possible. Provide appropriate dust control measures as needed. 1.3 The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are provided for information only and are not considered standard. 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appro- priate safety, health, and environmental practices and deter- mine the applicability of regulatory limitations prior to use. 1.5 This international standard was developed in accor- dance with internationally recognized principles on standard- ization established in the Decision on Principles for the Development of International Standards, Guides and Recom- mendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee. 2. Referenced Documents 2.1 ASTM Standards: 2 E11Speciﬁcation forWovenWireTest Sieve Cloth andTest Sieves 2.2 Other Documents: AOAC 935.29Moisture in Malt - Gravimetric Method (AOAC 2005) 3 NFTA 2.2.2.5Dry Matter by Oven Drying for 3 hr at 105 °C 4 3. Terminology 3.1 Deﬁnitions of Terms Speciﬁc to This Standard: 3.1.1 ambient conditions, n—a temperature of 20 to 30°C (68 to 85°F), less than 50% relative humidity. 3.1.2 beer, n—the mash after it has undergone fermentation and has been deemed complete by virtue of the carbohydrates being converted into renewable fuel by enzymes and ferment- ing organisms. 3.1.3 mash, n—a mixture or slurry of water (including recycled water streams) and ground grain. 3.1.4 prepared biomass, n—biomass that has been prepared according to this practice. 3.1.5 predominantly cellulosic, adj—feedstock that has an averageadjustedcellulosiccontentof75%,measuredonadry mass basis; furthermore, this “adjusted cellulosic content” is the percent of organic (non-ash) material that is cellulose, hemicellulose, or lignin. 4. Signicance and Use 4.1 Preparation Method A—Method suitable for the prepa- rationoflargequantities(20g)ofﬁeldcollectedsamplesinto 1 This practice is under the jurisdiction ofASTM Committee E48 on Bioenergy and Industrial Chemicals from Biomass and is the direct responsibility of Subcom- mittee E48.05 on Biomass Conversion. Current edition approved April 1, 2019. Published May 2019. Originally approved in 1995. Last previous edition approved in 2015 as E1757–01(2015). DOI: 10.1520/E1757-19. 2 For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [email protected] For Annual Book of ASTM Standards volume information, refer to the standard’s Document Summary page on the ASTM website. 3 Available from AOAC International, 2275 Research Blvd., Suite 300, Rockville, MD 20850-3250, http://www.aoac.org. 4 Available from National Forage Testing Association (NFTA), PO Box 1470, Stuart, FL 34995, https://www.foragetesting.org/. Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee. 1Copyright by ASTM Int l (all rights reserved); Mon Oct 21 14:48:32 EDT 2019 Downloaded/printed by University of Michigan (University of Michigan) pursuant to License Agreement No further reproductions authorizeda form appropriate for compositional analysis.Woody samples must ﬁrst be available as chips of a nominal 5 by 5 by 0.6cm (2by2by 1 ⁄4in.)orlessandtwigsnotexceeding0.6cm( 1 ⁄4in.) diameter. Herbaceous materials may be processed as whole straw. It is recommended that wastepaper should be shredded into pieces less then 1 cm ( 1 ⁄2 in.) wide. Furthermore, it is recommended that twigs, straw, and wastepaper should not exceed 61 cm (24 in.) in length to facilitate handling. 4.2 PreparationMethodsBandC—Methodsaresuitablefor very moist feedstocks, samples that would not be stable during prolonged exposure to ambient conditions, or for drying materials when room conditions deviate from the ambient conditions described in 3.1.1. These test methods are also suitable for handling small samples of biomass (20 g, and the intermediate model, with 1mm screen, is suitable for samples 20 g) of biomass as described in 4.1. 6.2 The raw biomass material should be spread out on a suitable surface to air dry prior to any milling. Do not pile the material deeper then 15 cm. Turn the material at least daily to ensureevendryingandminimizemoldingofmaterialthatmay contain signiﬁcant amounts of moisture. The material is considered dried when the change in weight is less than 1% in 24 h. 6.3 The air-dried material is fed into the knife-mill and is milledtopassthrougha2mmscreeninthebottomofthemill. Milled wastepaper does not need to be sieved and can be used directly for composition analysis. Milled biomass materials should be sieved as follows. 6.4 The sieving is set up by stacking the sieves in the following order, starting at the bottom: start with the bottom pan, next stack the 80 mesh sieve, followed by the 20 mesh sieve. Milled material is placed no more then 7 cm deep in the 20 mesh sieve. 6.5 Place the cover on the sieve stack and secure the stack in the sieve shaker. 6.6 Thesievesneedtobeshakenfor15 61min.Attheend of the time period remove the sieves. The fraction retained on the 20 mesh sieve (+20 mesh fraction) should be reprocessed beginning at step 6.3. The fraction retained on the 80 mesh sieve (20/+80 mesh fraction) should be retained for compo- sitional analysis. The material in the bottom pan is the ﬁnes (80 mesh). Retain this material for ash analysis. E1757 19 2Copyright by ASTM Int l (all rights reserved); Mon Oct 21 14:48:32 EDT 2019 Downloaded/printed by University of Michigan (University of Michigan) pursuant to License Agreement No further reproductions authorized6.7 Repeat6.3–6.6untilallofthemilledmaterialwillpass through the 20 mesh sieve. If necessary, combine all of the 20/+80 mesh batches. If necessary, combine all of 80 mesh batches. Weigh the combined 20/+80 mesh fraction and the combined ﬁnes to the nearest 0.1 g. Record the 20/+80 mesh fractionweightas Wt 20/80 andtheﬁnesfractionweightas Wt 80 . 6.8 If multiple sieved samples were combined they must be uniformlyblendedbacktogetherintoasinglesample.Pourthe 20/+80 mesh fraction into the riffle sampler, and then recom- bine the two subdivided samples in the bottom pans back together. Repeat this division and recombination an additional threetimes.Tocorrectlyusetherifflesampler,thesamplemust be poured evenly onto all the riffle openings at the same time. A pan, as wide as the riffle opening, should be used. Pour the sample evenly off the entire side of the pan and not from the end or the corner, nor from a container such as a jar. 6.9 If the total sample needs to be subdivided into smaller samples, use the riffler at this time to divide the main sample. 6.10 If the prepared sample is not analyzed immediately after sieving and riffling, the sample should be stored in an air-tight container or sealable polyethylene bag and kept at 20°C until needed. 7. Report: Preparation Method A 7.1 Calculate the percent of each fraction in the original, whole biomass: fraction 20/80 ,%5 ~Wt 20/80 3100%!/~Wt 20/80 1Wt 80 ! (1) where: Wt 20/80 = weight of 20/+80 mesh fraction, g, and Wt 80 = weight of ﬁnes fraction, g. fraction 80 ,%5 100%2fraction 20/80 % (2) 7.2 The mass fraction is used to weigh analytical results whenthetwofractionsdifferincomposition,buttheresultsare to be reported on the original, whole biomass. 8. Procedure: Preparation Method B 8.1 This method is suitable for very wet biomass that is at riskformoldgrowthduringdrying,forwetpretreatedbiomass or fermentation residues (sludges) that might degrade if al- lowed to stand for prolonged periods, or for drying biomass when the prevailing conditions do not meet the ambient conditions deﬁned in 3.1.1. 8.2 Dry a suitable container to hold the biomass at 45 6 3°C for a minimum of 3 h. Remove the container, place the container in a desiccator, and allow to cool to room tempera- ture. Weigh the container to the nearest 0.1 g and record this weight as W t . 8.3 Place the biomass material into the dried container. Do notpilethematerialdeeperthan1cm.Weighthecontainerand biomass to the nearest 0.1 g and record this weight as W i . 8.4 Place the container into a drying oven maintaining the temperature at 45 6 3°C. Allow the material to dry for 36 to 48h. 8.5 Remove the container and biomass from the drying oven, place in a desiccator, and allow to cool to room temperature. Weigh the container and biomass to the nearest 0.1 g and record this weight as W f . 8.6 For small quantities (20 g) containing material that would not pass through a 20 mesh screen, reduce the particle size for the solids by knife-milling the entire sample and sieve according to 6.3 – 6.7. 8.8 Return the milled sample to the drying oven, maintain- ing the temperature at 45 6 3°C. Keep the sample in the drying oven at 45 6 3°C for at least4h.Allow the samples tocooltoroomtemperatureinadesiccator.Weigheachsample to the nearest 0.1 mg and record this mass. After weighing, return the samples to the drying oven at 45°C for 1 h, cool again in the desiccator, and weigh again. Repeat this step until the mass of the samples varies by less than 1% from the previous weighing. 9. Report: Preparation Method B 9.1 Calculate the percent of the total solids obtained by drying at 45°C: %T 45 5 ~W f 2 W t !/~W i 2 W t ! 3100% (3) where: %T 45 = percent total solids in sample dried at 45°C, W t = tare weight of dried container, W i = initial weight of container and sample, and W f = ﬁnal weight of container and sample. 9.2 For larger milled and sieved samples calculate the percent of each fraction in the biomass dried at 45°C accord- ing to the equations in 7.1. 9.3 The mass fraction is used to weigh analytical results whenthetwofractionsdifferincomposition,buttheresultsare to be reported on the original, whole biomass. 10. Procedure: Preparation Method C 10.1 This method is suitable for very wet biomass that is at riskformoldgrowthduringdrying,forwetpretreatedbiomass or fermentation residues (sludges) that might degrade if al- lowed to stand for prolonged periods, or for drying biomass when the prevailing conditions do not meet the ambient conditions deﬁned in 3.1.1. This method is also suitable to handle materials that are heat sensitive and would degrade if subjected to the drying oven in Test Method B. 10.2 Weigh a suitable freeze-drier container to the nearest 0.1 g and record this weight as W t . 10.3 Placethebiomassmaterialintothecontainer.Forsolid samples do not ﬁll the container more than half full. For ﬂowable materials, that is, fermentation residues, ﬁll the container only with enough material to give a uniform coating of 0.5 cm on the walls of the container when the sample is frozen. Weigh the container and biomass to the nearest 0.1 g and record this weight as W i . E1757 19 3Copyright by ASTM Int l (all rights reserved); Mon Oct 21 14:48:32 EDT 2019 Downloaded/printed by University of Michigan (University of Michigan) pursuant to License Agreement No further reproductions authorized10.4 Place the container into a dry ice/acetone slush and slowly turn the container (10 r/min) to freeze the material into a uniform layer on the walls of the container. 10.5 Immediatelyplacethecontaineronthefreeze-drierand allow the material to dry until all visible traces of ice and frost are gone from the sample. Typically this takes 12 h for small (20 g) containing material that would not pass through a 20 mesh screen, reduce the particle size for the solids by knife-milling the entire sample and sieve according to 6.3 – 6.7. 10.9 Use this prepared sample immediately for composi- tional analysis. 11. Report: Preparation Method C 11.1 Calculate the percent of the total solids obtained by freeze-drying: % T fd 5 ~W f 2 W t !/~W i 2 W t ! 3100% (4) where: %T fd = percent total solids of a freeze-dried sample, W t = tare weight of freeze-drier container, W i = initial weight of container and sample, and W f = ﬁnal weight of container and sample. 11.2 For larger milled and sieved samples calculate the percent of each fraction in the freeze-dried biomass according to the equations in 7.1. 11.3 The mass fraction is used to weigh analytical results whenthetwofractionsdifferincomposition,buttheresultsare to be reported on the original, whole biomass. 12. Procedure: Preparation Method D 12.1 This method is suitable for cereal grains, cereal grain fermentation mash, cereal grain fermentation beer, and cereal grain fermentation residues that are generally stable. 12.2 Place substrate to be dried on a pan of suitable size to ensure good surface area exposure of the sample. 12.2.1 Discussion—The substrate should form a sufficiently thin layer in the drying pan that allows the sample to be dried to a moisture content of less than 8% within 48 h. 12.3 Place the pan into a drying oven maintaining the temperature at 50 6 3°C. Allow the material to dry for up to 48 h. 12.3.1 A vacuum may be applied to speed up the evapora- tion process. 12.3.2 It has been demonstrated that using sample prepara- tion drying temperatures above 65°C when drying and prepar- ingsamplesforanalysiscancausetheformationofretrograded starch which can lead to the generation of erroneous results. The scientiﬁc literature is replete with exa