Sensitivity of whole wood stable carbon and oxygen isotope values to milling procedures

Abstract

Milling of wood samples for carbon and oxygen isotope analyses is an appropriate preparation method.

Contamination risk of stable isotope samples during milling

“…A ball mill equipped with holders to mill wood samples in polypropylene sample tubes may be suitable for δ 18 O analysis: no oxygen atoms are present in plastic, and, hence, we found no evidence that δ 18 O values would be affected by plastic contamination. We also did not detect any evidence of fractionation from heating, which is in line with a previous experiment …”

“…We found similarly poor homogenization when milling samples with liquid. Accordingly, we cannot recommend milling with a ball mill, in direct disagreement with the recommendations made by a previous study …”

“…We also did not detect any evidence of fractionation from heating, which is in line with a previous experiment. [40] Using a ball mill is not advisable for milling wood prior to δ 13 C radiocarbon measurement. Changes in isotope values due to plastic contamination were most concerning for smaller amounts (10 mg).…”

“…The resulting homogenized material is then ready for cellulose extraction or for mass spectrometric analysis of whole wood (resins and extractives may have to be removed first). After a recent study found no evidence of isotope fractionation due to heating from friction of wood samples during ball milling, the ball mill was explicitly recommended for tree‐ring isotope research …”

“…After a recent study found no evidence of isotope fractionation due to heating from friction of wood samples during ball milling, the ball mill was explicitly recommended for tree-ring isotope research. [40] The ball-mill configuration became a matter of concern, however, after unpublished isotope data showed atypical patterns: radiocarbon measurements of the same samples indicated the presence of 'dead carbon'. These atypical results might have stemmed from sample-tube abrasion during milling, which could taint the sample with plastic.…”