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NOSAMS > Sample Requirements > Standard AMS Analysis

General Sample Requirements for regular AMS analysis

For analysis in one of our accelerator mass spectrometers (AMS), the ideal sample size is 1 milligram of pure extracted carbon. We routinely analyze much less than this (0.020 - 1 mg C), however the smaller the mass analyzed, the greater the uncertainty due to the effects of the process blank and fewer 14C counts detected (small mass means fewer carbon atoms and the older the sample, the fewer the radiocarbon atoms due to decay). While AMS allows the precise measurement of radiocarbon from tiny amounts of material, the potential resolution can easily be obscured by analyzing extraneous components or by the process blank.

The recommended sample sizes provided below are based on an ideal 1 milligram carbon sample mass for clean dry material free from impurities such as adhering sediment, rootlets or other extraneous materials.

The steps you take to prepare your sample for AMS analysis are by far the most important determinant of the quality of the radiocarbon result. Your choices define the sample and determine the scope of questions that can ultimately be addressed.

For information on how to submit samples click here.

General guidelines for 1 milligram extracted carbon sample size are provided below.

Sample TypeRecommended Sample Size for AMS analysisPretreatment included
Inorganic Carbon Sample Type
Marine carbonates:
Foraminifera8-12 milligrams
Coral8-12 milligrams

pre-acid etch upon request

Mollusk8-12 milligrams

pre-acid etch upon request

Otolith8-12 milligrams
Water Dissolved Inorganic C (DIC)depends on DIC concentration
Sediment - carbonate mineralsdepends on the % carbonate
Carbonates - carbonate shell samples are expected to arrive free from sediments and extraneous material, ready to be directly acidified. To estimate the milligrams of carbon in carbonate, use the formula mg C = mg CaCO3/8.33 then multiply by 0.9 to account for impurities. If δ13C analysis is requested, this will consume up to 9 % of the CO2 generated via acidification.
Organic Carbon Sample Type
Plant/Wood3 mg

Acid-base-acid pretreatment applied

Charcoal5 mg

Acid-base-acid pretreatment applied

Sediment (OC)depends on %OC

Acidification or acid fuming on request

Compound-specific (CSRA)depends on %OC
Water DOCdepends on DOC concentration
Proteinaceous corals3-4 mg
POC or aerosols on filtersdepends on %OC

Acid fuming

black carbon
Pretreatment – Unprocessed plant based materials undergo a series of acid-base-acid leaches to remove any inorganic carbon or base-soluble organic acids prior to combustion. If your samples are very small and/or friable, we may contact you to discuss pretreatment options before processing them to decide on the best approach.
Gas Sample Type
Pure CO280 micromoles, 2-9 umols considered small
Methane in gas or water> 3 umols methane
CO2 or methane in a gas mixture> 3 umols
Small sample fee/processing - samples yielding between 2- 9 micromoles CO2 (25 - 100 micrograms C) are considered small samples. An additional small sample analysis surcharge applies. See fees.
Other Sample Types
Graphite0.025 - 1 milligram C
Single Step Reduction for Organic Carbon Samples

For information on the sample submission process click here.