Our instruments determine total carbon, hydrogen, and nitrogen content by means of high-temperature (1000C) combustion (Dumas method) of microgram to milligram size samples in an oxygen-enriched helium atmosphere. The combustion products CO2, NOX (reduced to N2), and H2O  are separated by means of sequential, selective chemical traps, and measured with three pairs of high-precision thermal conductivity detectors. Interfering gases of sulfur, halogens, and phosphorus are removed in the combustion reactor using the appropriate solid reagents. Samples, which have been precisely weighed into small tin capsules, placed in protective nickel sleeves for the analysis. Analysis results are reported in weight percent of the element.

In addition to solid sample materials, total organic matter trapped on glass fiber filters can be analyzed. Filters are not weighed, but are placed directly into nickel sleeves for analysis. (A nickel sleeve can accommodate a filter of up to 25mm diameter.) Two sample capsules can be combusted together in a single analysis, called "double-drop,". This method accommodates larger total sample weights (for low organic-content materials) and larger diameter glass fiber filters (up to 47mm) can be analyzed. Results are reported in absolute micrograms of the element on the filter.

Before collecting samples, filters must be pre-combusted at 450°C for 30 minutes. Whatman filters, either GFC or GFF, provide low background contamination and are highly preferred. Filters up to 25mm in diameter are analyzed whole and are considered as 'Regular' on our rate schedule. Larger filters up to 47mm in diameter are too big to analyze whole and must be cut in half for analysis. Both halves are analyzed simultaneously by "double drop" and fall under the CHN-Other rate category.

After collection, filters should be placed in a 60°C drying oven and must be submitted completely dry. They should contain no more than 4mg of dried material. If more than 4mg of material is present, or if you have other concerns, please contact the Analytical Lab. Be sure to include filter blanks along with the samples.

Filters submitted to the Analytical Lab for Organic Carbon analysis (POC) should be treated with hydrochloric acid (HCl) to remove inorganic carbonates. After acidification, filters should be placed in a 60°C drying oven and must be submitted completely dry. The Analytical Lab can provide the acidification service upon request.

Glass or plastic scintillation-type vials are the preferred containers. Plastic petri dishes with secure lids or microfuge tubes also work well. Wrapping filters in aluminum foil is not recommended, as filters have a tendency to stick to the foil during drying and sample losses may occur.

Biological samples typically require 2-3mg of sample per analysis. For materials with low organic content, a larger amount of material will be analyzed to obtain a signal within the optimal range. We ask that 10-100mg of sample be provided. If less than 10mg of material is available, or if you have other concerns, please contact the Analytical Lab.

Samples must be thoroughly dried and finely ground to a powder. Sample homogeneity is usually the limiting factor for analytical precision.

Biological materials submitted to the Analytical Lab for Organic Carbon analysis (TOC) should be treated with acid (H2SO3) to remove inorganic carbonates. It is best to weigh samples into silver capsules first, then acidify gently with multiple aliquots of H2SO3. After acidification, samples should be placed in a 60°C drying oven to dry completely before closing the sliver capsule. The Analytical Lab can provide the acidification service upon request.

Screw-cap glass vials are the preferred containers.

Geological samples typically require 10-50mg of sample per analysis. For materials with ultra low organic content, two aliquots may be analyzed simultaneously by "double drop" and fall under the CHN-Other rate category. We ask that 100-1000mg of sample be provided. 

Samples must be thoroughly dried and finely ground to a powder. Sample homogeneity is usually the limiting factor for analytical precision.

Geological materials submitted to the Analytical Lab for Organic Carbon analysis (TOC) should be treated with acid (H2SO3) to remove inorganic carbonates. It is best to weigh samples into silver capsules first, then acidify gently with multiple aliquots of H2SO3. After acidification, samples should be placed in a 60°C drying oven to dry completely before closing the sliver capsule. The Analytical Lab can provide the acidification service upon request.

Screw-cap glass vials are the preferred sample containers.

Synthetic samples typically require 1-2mg of sample per analysis, but sample size requirements vary depending on the theoretical elemental composition. We ask that 10mg of sample be provided. If less than 10mg of material is available, or if you have other concerns, please contact the Analytical Lab.

Samples must be thoroughly dried and finely ground to a powder. Sample homogeneity is usually the limiting factor for analytical precision.

Screw-cap glass vials are the preferred sample containers.

The Analytical Lab does not prepare samples for analysis in a glove box. If you are submitting air sensitive or hazardous materials, please contact the Analytical Lab with details and we'll do our best to work with you.