Plant Tissue Nitrogen-15 Analysis
by Isotope-Ratio Mass Spectrometry

Last revised July 22, 1997

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[Overview of technique]

[Sample prep considerations]

Isotope-ratio analysis for nitrogen-15 in solid-phase samples such as plant tissue starts with transformation to gas phase by extremely rapid and complete flash combustion of the sample material. Ionized combustion product (dinitrogen) is mass-analyzed by means of differing mass/charge ratios among the various isotopic species of N2. A great many more details of the process are available in the [Process Overview] and [Practical Considerations] documents.

Plant samples must be oven-dried, ball-milled to less than 250 um particle size and weighed (~3 mg, with ug digits significant) into 5 x 5 mm tin capsules before combustion. Poor precision can often be traced to inadequate grinding that leaves fibrous matter or visible granules in the sample. Sample prep for plant 15N analysis is set out in exhaustive detail in the [Sample Collection] instructions.

Clients may send us unprocessed samples (e.g. leaves, stems, roots) or may provide any of the above processing themselves at a major reduction in price. Please refer to the [Fee Schedule] page.