Improving accuracy and sensitivity of isotope ratio mass spectrometry for δ13C and δ15N values in very low mass samples for ecological studies

• Published in: Soil biology & biochemistry Vol. 65; pp. 75 - 77
• Main Authors: Crotty, Felicity V., Stocki, Myles, Knight, J. Diane, Adl, Sina M.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Ltd 01.10.2013; Elsevier
• Subjects: Agronomy. Soil science and plant productions; Biochemistry and biology; Biological and medical sciences; biomass; Chemical, physicochemical, biochemical and biological properties; chromium; Collembola; detection limit; Food webs; Fundamental and applied biological sciences. Psychology; isotopes; Mass spectrometry; Microarthropods; microorganisms; Nutrient flow; oxygen; Physics, chemistry, biochemistry and biology of agricultural and forest soils; reference standards; Soil ecology; Soil science; Stable isotopes; Zoology (interactions between soil fauna and agricultural or forest soils); Food webs; Microarthropods; Nutrient flow; Mass spectrometry; Stable isotopes; Soil ecology; Meiofauna; Carbon isotope discrimination; Fauna; Isotopic composition; Ecology; Trophic chain; Soils; Accuracy; Food web; C-13; Arthropoda; Nutrient; Nitrogen-15; Soil science; Invertebrata; Ecological approach; Isotopes; Nitrogen isotope discrimination
• ISSN: 0038-0717; 1879-3428
• DOI: 10.1016/j.soilbio.2013.04.020

A modified procedure for isotope ratio mass spectrometry (IRMS) of 13C/12C and 15N/14N ratios of very low biomass samples yielded reproducible data and enhanced the resolution of the instrument beyond its typical detection limit. The main modification was to rely only on oxygen from the chromium oxide catalyst allowing greater precision of measurement. Our method was accurate to weights of 8 μg C and 2 μg N with reference standards and test materials. The collembolan could be measured accurately enough for differences between individuals to be detectable. Attaining this level of resolution with ecological samples makes it feasible to use IRMS while retaining sample mass small enough to be functionally useful in studies of micro-organism food webs. •We demonstrate resolution of very small sample mass <10 μg.•A small number of individual microarthropods per sample were sufficient.•Dry weights of 8 μg C and 2 μg N could be measured.•Calibrated accuracy of ±0.00001 atom% was maintained.