<abstract xmlns="http://www.w3.org/1999/xhtml">The radiocarbon laboratory at the Lebanese Atomic Energy Commission is undertaking environmental studies, in order to determine the anthropogenic impact of technologies on the ecosystem through the determination of radiocarbon content in tree leaves and plants. Thus, it was important to validate the method used to demonstrate that the applied procedure gives reliable results. Method validation is universally applied in analytical laboratories as an essential part of quality assurance system and as a basic technical requirement of the ISO 17025 standard. The conventional method used for determination of Fraction Modern (F14C) is a standard method issued by the American Society for Testing and Materials in 2011 with a code ASTM-D 6866-11 Method C. According to Eurachem guide, internal validation was expressed in terms of accuracy that was evaluated by trueness and precision. Trueness was expressed in terms of relative bias, while for precision ten consecutive replicates were carried out to under repeatability conditions and five duplicates were analyzed under reproducibility conditions. The limit of detection and the minimum detectable activity (MDA) were calculated. Uncertainty sources were defined and their relative standard uncertainties were calculated in order to determine the combined standard uncertainty. Five reference samples of different matrices were analyzed; calculated z score values were acceptable as being between –2 and +2. The calculation and results are presented in this work.</abstract>

The radiocarbon laboratory at the Lebanese Atomic Energy Commission is undertaking environmental studies, in order to determine the anthropogenic impact of technologies on the ecosystem through the determination of radiocarbon content in tree leaves and plants. Thus, it was important to validate the method used to demonstrate that the applied procedure gives reliable results. Method validation is universally applied in analytical laboratories as an essential part of quality assurance system and as a basic technical requirement of the ISO 17025 standard. The conventional method used for determination of Fraction Modern (F14C) is a standard method issued by the American Society for Testing and Materials in 2011 with a code ASTM-D 6866-11 Method C. According to Eurachem guide, internal validation was expressed in terms of accuracy that was evaluated by trueness and precision. Trueness was expressed in terms of relative bias, while for precision ten consecutive replicates were carried out to under repeatability conditions and five duplicates were analyzed under reproducibility conditions. The limit of detection and the minimum detectable activity (MDA) were calculated. Uncertainty sources were defined and their relative standard uncertainties were calculated in order to determine the combined standard uncertainty. Five reference samples of different matrices were analyzed; calculated z score values were acceptable as being between –2 and +2. The calculation and results are presented in this work.

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

Geochronometria

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

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

The radiocarbon laboratory at the Lebanese Atomic Energy Commission is undertaking environmental studies, in order to determine the anthropogenic impact of...

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	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

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		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
	σ_r	0.01
	r_L	0.02
	CV	2.70%
Reproducibility	Mean	0.24
	σ_r	0.01
	R_L	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

Sample Code	Sample type	Reference value (F¹⁴C) Reference value = pMC reference/100	σ_target	Lab Value (F¹⁴C)	σ_Lab	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

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

Article Category: Regular Articles

Data publikacji: 21 lut 2018

Zakres stron: 68 - 73

Otrzymano: 16 mar 2015

Przyjęty: 29 wrz 2017

DOI: https://doi.org/10.1515/geochr-2015-0080

Słowa kluczowe
radiocarbon, method validation, ISO 17025, Eurachem Guide, Fraction Modern

© 2015 R. Baydoun., published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Fig. 1

Fig. 2

The ten Fraction Modern (F14C) values obtained under repeatability condition.

Counting region optimization data for glass vial.

The four Fraction Modern (F14C) values obtained under reproducibility condition.

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

Reference values, Lab values and z-score values.

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

Article Category: Regular Articles

Data publikacji: 21 lut 2018

Zakres stron: 68 - 73

Otrzymano: 16 mar 2015

Przyjęty: 29 wrz 2017

DOI: https://doi.org/10.1515/geochr-2015-0080

Słowa kluczoweradiocarbon, method validation, ISO 17025, Eurachem Guide, Fraction Modern

© 2015 R. Baydoun., published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Fig. 1

Fig. 2

The ten Fraction Modern (F14C) values obtained under repeatability condition.

Counting region optimization data for glass vial.

The four Fraction Modern (F14C) values obtained under reproducibility condition.

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

Reference values, Lab values and z-score values.

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

Słowa kluczowe
radiocarbon, method validation, ISO 17025, Eurachem Guide, Fraction Modern