C/N of Solid Samples

Biogeochemical Stable Isotope Facility

School of Ocean and Earth Science and Technology

Approximate sample sizes for commonly analyzed materials:

δ13C, δ15N analysis of solid samples and filters

Single Isotope Analysis

Nitrogen:  20 μg minimum is required for optimal analysis.  Samples should not contain more than ~1 mg of carbon.  If your C/N ratio is very high, such that you will exceed the acceptable C content to achieve the optimal N amount, we can analyze down to 15 μg N with acceptable accuracy and precision.  Below this level, the δ15N value become less precise depending on sample type and homogeneity.

Carbon: The optimal range for C is 200 - 600 μg C, though we can analyze as low as 10 μg.  Sample sizes that are consistent and close to the optimal amounts listed above will give the best precision and accuracy. 

Dual Element & Isotope Analysis

Since the C/N of many materials do not allow one to target the ideal amounts of each element simultaneously, some compromise on sample size has to be made such that the carbon content cannot exceed 1200 μg and the N should not fall below 20 μg.  If it is not possible to meet these criteria, then it may be necessary to analyze two separate samples.  

 Animal tissue: 400-500 μg

 Plant tissue: 2-3 mg

 Soil/Sediment: 2 - 30 mg, depending on OM content

Lab Phone: 808-956-5362

Fax: 808-956-5512

Lab Email: isobiogeo@soest.hawaii.edu

 

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