TITLE:
Validation and Comparison of Two Calibration Methods for the Measurement of Stable Iodine in the Urinary Matrix by ICP-MS: Standard Addition vs. External Calibration
AUTHORS:
Géraldine Landon, Céline Bouvier-Capely, Alexandre Legrand, Thibaud Sontag, Grégory Finance, Maïlie Saint-Hilaire, François Rebière, Xavier Millot, Valérie Renaud-Salis, Michelle Agarande
KEYWORDS:
Stable Iodine, Urine, Standard Addition, External Calibration, Validation
JOURNAL NAME:
American Journal of Analytical Chemistry,
Vol.8 No.4,
April
14,
2017
ABSTRACT: Background: In
the context of a nuclear reactor accident, thyroid is the main target organ of
radioactive iodines. To avoid as much as possible thyroid disorders or even
cancer development, it is recommended to administer a single dose of potassium
iodide to people at risk of exposure. Nevertheless, the Fukushima Dai-ichi
disaster has pointed out many questions about the conditions of stable iodine
prophylaxis implementation highlighting the need for reflection further
revision of the actual “iodine doctrine”. Therefore, providing useful data is required
notably through the implementation of animal experiments to strengthen current
knowledge and to edit new recommendations. Methods: Urinary iodine
constitutes a very
good indicator to investigate the function of thyroid, its interpretation
demands reliable analyses. Prior
to perform animal experiments, two calibration methods were designed by our lab
and compared together (standard addition and external calibration) to assess
the urinary concentration of stable iodine in urine by ICP-MS. They were
validated based on several key parameters especially linearity, accuracy and
limits of detection (LOD) and quantification (LOQ). Results: The
results were nicely satisfying. Indeed, both calibration methods have indicated
very good coefficients of correlations, accuracies with low
expanded relative uncertainties were obtained. The estimated LOD in the sample
for standard addition method and external calibration were fully acceptable,
0.39 μg·L-1 and 0.35 μg·L-1,
respectively. All performance criteria have been thus fulfilled successfully. The established methods
were proven to be accurate, robust and sensitive. Once validated, both
calibration methods were applied to rat
urine samples and the results of z-score and Wilcoxon W test concluded that there were no
statistically significant differences between both methods.