An economical method for the preparation of plant and animal tissue for δ¹³C analysis

This study describes an economical and simple apparatus and methodology for preparing plant material for δ13C analysis by the combustion of material in sealed Pyrex tubes at 550°C. The largest difference in δ13C for samples combusted at 550°C in Pyrex tubes compared with those combusted at 800°C in the more expensive Vycor tubes was 0.65 δ units. Pyrex combustion tubes are approximately 7% of the cost of Vycor tubes and are easier to handle. Excellent reproducibility was observed with an average standard deviation for samples combusted at 550°C and 800°C of 0.12 and 0.13 units of δ13C, respectively. During the cryogenic distillation of CO2 from the other gasses generated during the combustion, equilibration and evacuation times were varied between 10 s and 120 s. Sample size was varied between 0.4 mg and 2.2 mg. Variations in evacuation time, equilibrium time, and sample size did not significantly affect the value for δ13C. The total duration for the cryogenic distillation of one sample was approximately 5 min. In inter‐laboratory comparisons, the values for δ13C of various plant samples were found not to be significantly different. Notes Department of Biology, University of Saskatchewan, Saskatoon, SK, S7N OWO, Canada. Department of Range Science, Texas Agricultural Experiment Station, Texas A&M University, College Station, Texas 77843. Contribution of the Saskatchewan Institute of Pedology, Publication No. R646.