NSRL participated in the Fourth International Radiocarbon Intercomparison (FIRI). Samples underwent routine processing at NSRL and ¹⁴C measurement was performed under normal operating conditions at NOSAMS.

Standard ID	Sample Type	Fcons1	FNSRL2	Difference ‰3
FIRI A/B	wood (kauri)	0.00170	0.00320	1.5
FIRI C	turbidite calcite	0.10398	0.10500	1.0
FIRI D/F	wood (Belfast Scots pine)	0.56975	0.56635	-3.4
FIRI E	humic acid	0.23003	0.22900	-1.0
FIRI G/J	modern barley mash	1.10520	1.09835	-6.9
FIRI H	wood (Hohenheim oak)	0.75684	0.75760	0.8
FIRI I	cellulose	0.57231	0.56770	-4.6

¹ Consensus fraction modern. This is the mean result for all participating AMS labs.
² Fraction modern measured by NSRL
³ Difference between NSRL result and consensus value, in ‰ notation. [1000 (F_NSRL-F_cons)]

Inter-laboratory calibration can also be assessed by comparison of overlapping series of AMS ¹⁴C results for carbonate samples from sediments of the Cariaco Basin, prepared and measured at NSRL-NOSAMS and LLNL-CAMS. Click here to view.