Premium
Contamination risk of stable isotope samples during milling
Author(s) -
IsaacRenton M.,
Schneider L.,
Treydte K.
Publication year - 2016
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.7585
Subject(s) - contamination , chemistry , ball mill , sample preparation , cellulose , grinding , isotope analysis , pulp and paper industry , chromatography , metallurgy , materials science , geology , ecology , organic chemistry , engineering , biology , oceanography
Rationale Isotope analysis of wood is an important tool in dendrochronology and ecophysiology. Prior to mass spectrometry analysis, wood must be homogenized, and a convenient method involves a ball mill capable of milling samples directly in sample tubes. However, sample‐tube plastic can contaminate wood during milling, which could lead to biological misinterpretations. Methods We tested possible contamination of whole wood and cellulose samples during ball‐mill homogenization for carbon and oxygen isotope measurements. We used a multi‐factorial design with two/three steel milling balls, two sample amounts (10 mg, 40 mg), and two milling times (5 min, 10 min). We further analyzed abrasion by milling empty tubes, and measured the isotope ratios of pure contaminants. Results A strong risk exists for carbon isotope bias through plastic contamination: the δ 13 C value of polypropylene deviated from the control by −6.77‰. Small fibers from PTFE filter bags used during cellulose extraction also present a risk as the δ 13 C value of this plastic deviated by −5.02‰. Low sample amounts (10 mg) showed highest contamination due to increased abrasion during milling (−1.34‰), which is further concentrated by cellulose extraction (−3.38‰). Oxygen isotope measurements were unaffected. Conclusions A ball mill can be used to homogenize samples within test tubes prior to oxygen isotope analysis, but not prior to carbon or radiocarbon isotope analysis. There is still a need for a fast, simple and contamination‐free sample preparation procedure. Copyright © 2016 John Wiley & Sons, Ltd.