The Central Radiocarbon Laboratory uses two different analytical techniques for 14C analysis - low level counting (LLC) for high volume CO2 samples and Accellerator Mass Spectrometry (AMS) for small (flask) air samples. Find a few impressions of our laboratory in the following.
ICOS small air sample containers (flasks)
A share of the 3-litre flask samples collected at ICOS class 1 stations is analysed for 14CO2 by Accellerator Mass Spectrometry after they had been analysed for GHG concentrations and stable istopes at the ICOS Flask and Calibration Laboratory. Samples are shipped between stations and ICOS Laboratories in specially designed Zarges boxes.
ICOS CRL flask CO2 Extraction and Graphitization Line (EGL)
A dedicated semi-automated CO2 extraction and graphitisation line for flask samples was developed in the CRL to prepare the up to 1500 small air samples for AMS 14CO2 analysis. The line is designed to prepare also graphite targets from pure CO2 sample aliquots of the high-volume CO2 samples. For quality control of the entire flask extraction procedure, a Laser spectrometer is included in the preparation line to allow precise stable isotope analysis of the extracted CO2.
ICOS CRL graphitization ovens of the EGL
In total twelve CO2 samples can be graphitized in parallel in the Extraction and Graphitisation Line. We use iron powder as catalyst and hydrogen gas for reduction of the CO2 to graphite for AMS 14C analysis.
ICOS CRL CO2 sample aliquot preparation
From each high volume integrated conventional 14CO2 sample three aliquots are transferred into break seals to allow parallel analysis of the sample by AMS (inter comparison to low level counting and quality control) and for creating a CO2 air sample archive (for potential later analysis).
ICOS CRL high-volume sample preparation lab for 14C low level counting
The integrated high volume 14CO2 samples, which are collected from about 20m3 of air by chemical absorption in sodium hydroxide solution, are extracted from the basic solution in a vacuum system by additing phosphoric acid and are transferred into high-pressure stainless steel containers.
ICOS CRL high-volume sample purification system
CO2 from the extracted high-volume samples is purified over charcoal to allow direct counting in the low-level counters of the IUP underground laboratory.
ICOS CRL underground laboratory
In total 19 counters are available for measurement of the high-volume CO2 samples in the IUP underground laboratory. Counters are shielded by low-activity lead; here the samples are measured at least for one week in two different counters to reach sufficient 14C counting statistics and achieve highest possible precision.
MICADAS 14C Accellerator Mass Spectrometer at CEZA
Few miligrams of graphite from CO2 of the small volume flask samples are analysed for 14C by AMS at the Curt Engelhorn Cetre for Archaeometry in Mannheim, Germany.