Materials and Reagents

1. Nonstructural carbon and cellulose
   1. MQ H₂O
      
   2. Laboratory grade pure methanol for cleaning
   
   
2. Nonstructural carbon
   1. ¹⁴C standards [international secondary standards: ANU sucrose (IAEA-C6), in-house laboratory standards, e.g. wheat flour, rye flour]
      
   2. Laboratory-grade ethanol
      
   3. HPLC-grade ethanol
      
   4. Analytical-grade 20% HCl [≈ 6 M HCl, 50:50 (v: v) conc. HCl]
   
   
3. Cellulose
   1. ¹⁴C standards (international secondary wood standards: e.g. IAEA-C4, -C5)
      
   2. Laboratory-grade toluene
      
   3. Laboratory-grade glacial acetic acid (CH₃COOH)
      
   4. Technical grade sodium chlorite (NaClO₂)

Equipment

1. Nonstructural carbon and cellulose
   1. Aluminum (Al) foil (cover surfaces and prevent dust contaminating equipment and samples with extraneous carbon)
      
   2. Marker pen
      
   3. Spatula
      
   4. Wipes for cleaning (e.g. KCWW)
      
   5. Duster for cleaning (I L) (e.g. Innovera^TM)
      
   6. Pyrex beakers to hold reagents
      
   7. Graduated volumetric cylinder to prepare reagents
      Note: All glassware is baked and stored covered with Al foil to remove extraneous sources of carbon. Quartz is pre-combusted at 900 °C for 2 h, Pyrex at 550 °C for 3 h.
   
   
2. Nonstructural carbon
   1. Mill with mesh 10 or scalpel
      
   2. Graduated, adjustable volume, 5 ml pipette (e.g. VWR International, Eppendorf) or cylinder
      
   3. Disposable borosilicate glass culture tubes (13 x 100 mm) with plastic vented caps and snap caps (VWR International)
      
   4. Disposable, plastic (extended fine tip) transfer pipette (e.g. Thermo Fisher Scientific, Samco Scientific)
      
   5. Quartz combustion tubes (120 mm length, 9 mm O.D.)
      
   6. 50 ml reusable glass centrifugation tube with screw cap or plastic (e.g. PP) centrifuge tubes with screw cap
      
   7. Speedvac-dryer (Thermo Fisher Scientific, Savant, model: SC200 speedvac with RT400 cold trap) (operated at room temperature)
      
   8. Block heater with thermometer for 10 or 20 (13 x 100 mm) disposable borosilicate glass culture tubes
      
   
   
3. Cellulose
   1. General-purpose extra-long, stainless steel forceps
      
   2. Quartz combustion tubes (150 mm length, 6 mm O.D.)
      
   3. Heat sealer
      
   4. 1,000 ml pyrex beaker
      
   5. 1,000 ml pyrex round bottom flask (still pot)
      
   6. Soxhlet extraction apparatus (e.g. VWR International)
      
   7. Heated magnetic stirrer & stir bar
      
   8. Drying oven
      
   9. Cork ring
      
   10. Boiling chips
       
   11. Fiber filter bags for sample digestion (ANKOM Technology, catalog number: F57 )

Procedure