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

Abstract

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.