Elemental Analyses of Solid Samples
We have a Carlo Erba NA 2500 elemental analyzer coupled with a Finnigan Delta S mass spectrometer. We accommodate many types of samples, such as plants, animal tissue, phytoplankton, algae (a.k.a. limu), and various sizes of glass fiber filters. One analysis/combustion of a sample can yield both N and C quantification and isotopic composition.
Single Isotope Analysis
Nitrogen: 20 ug 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 ug N with acceptable accuracy and precision. Below this level, the d15N value become less precise depending on sample type and homogeneity.
Carbon: The optimal range for C is 200 - 600 ug C, though we can analyze as low as 10 ug. 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 does 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 ug and the N should not fall below 20 ug. If it is not possible to meet these criteria, then it may be necessary to analyze two separate samples.
Approximate sample sizes for commonly analyzed materials:
Samples have to be acidified (if necessary), dried, finely ground (except for glass fiber filters), weighed (using a microgram balance), and packaged in tin capsules prior to analyses.
Cost of analyses are as follows:
| Prepared Samples*: C & N, only C, or only N | $10 |
| Prepared Filters (up to 25 mm in diameter) | $12 |
| Unprepared samples**
grinding weighing acidification filter prep (drying, sub-sampling, folding) |
various
$2.50 $2.50 $2.50 $3.00 |
*If your C/N is larger than 25, separate analyses for carbon and nitrogen will most likely be necessary. In this case, total will be $16 for analyses of both C and N (not including prep if applicable).
**If you are studying macroalgae or sediments that contain carbonate material, acidification will be required to measure organic carbon quantity and isotopic signature. With some materials, it has been observed that acidification will cause a nitrogen isotopic offset. A test trial may be run to determine if this is the case with your sample material. If so, we may need to run one unacidified analysis for nitrogen isotopes and one acidified analysis for carbon isotopes. In this situation, where two analyses are required to get carbon and nitrogen isotopes, the cost is $16, as in the case of a C/N larger than 25.
***We are able to grind and weigh samples for you if necessary. We prefer that the samples come to us completely dried, but can help you arrange for this process if absolutely necessary.
If you'd like to have us analyze your samples, please fill out the Sample Request Form.
Guidelines for sample preparation
Solid Samples (Microsoft Office Word Document)
Filters (Microsoft Office Word Document)
Acidified Samples (Microsoft Office Word Document)
Sample Prep Spreadsheet (Microsoft Excel Spreadsheet)
Important things to keep in mind...
Thumbnails of prepared samples:
Good Solid Sample Bad Solid Sample Good filter (sideways) Good filter (Top)
Nicely wrapped samples will be tight and secure. Avoid edges sticking out or flat configurations, as they can get caught in the autosampler and create serious problems.