Method validation for the determination of fraction of modern (F¹⁴C) in wood samples using conventional method

Fig. 1

Fig. 2

The ten Fraction Modern (F14C) values obtained under repeatability condition_

Number of repetition	Value of F14C
1	0.224 ± 0.006
2	0.241 ± 0.007
3	0.237 ± 0.006
4	0.225 ± 0.006
5	0.242 ± 0.007
6	0.230 ± 0.006
7	0.236 ± 0.006
8	0.240 ± 0.007
9	0.230 ± 0.006
10	0.231 ± 0.006

Counting region optimization data for glass vial_

Counting region	Background of blank sample (cpm)	Standard (cpm)	Efficiency (%)	FOM (E2/B)
20–85	0.42 ± 0.04	1072 ± 2	60	8571
15–105	0.63 ± 0.04	1276 ± 2	70	7778
10–95	0.93 ± 0.05	1407 ± 3	77	6375

The four Fraction Modern (F14C) values obtained under reproducibility condition_

Number of repetition	Value of F14C
1	0.244 ± 0.008
2	0.235 ± 0.006
3	0.227 ± 0.006
4	0.242 ± 0.007

Validation parameters for the determination of Fraction Modern (F14C) by conventional method when counting 4g benzene for 300 minutes_

Validation parameters		Value
Method Bias		1.51%
Repeatability	Mean Reference value = pMCreference/100 = 0.2305 ± 0.0002	0.23 Reference value = pMCreference/100 = 0.2305 ± 0.0002
	σr	0.01
	rL	0.02
	CV	2.70%
Reproducibility	Mean	0.24
	σr	0.01
	RL	0.02
	CV	3.30%
Limit of detection	Ld (counts)	2.98
Minimum Detectable Activity	MDA (dpm)	0.003
Combined uncertainty	U(pMC)	0.58

Reference values, Lab values and z-score values_

Sample Code	Sample type	Reference value (F14C) Reference value = pMC reference/100	σtarget	Lab Value (F14C)	σLab	z-score	tSIE tSIE =Transformed Spectral Index of the External Standard, the quench parameter
D	Barley	0.1030	0.0100	0.1038	0.0210	0.04	682
U	Humic acid	0.2308	0.0002	0.2298	0.0083	–0.12	683
R	Murex shell	0.7334	0.0004	0.7210	0.0176	–0.70	685
IAEA-C2	Travertine	0.4114	0.0003	0.4217	0.0114	0.90	682
IAEA-C7	Oxalic acid	0.4935	0.0012	0.4810	0.0130	–0.96	680