Fig 1.
Sample cells containing nail clipping fragments prepared for XRF analysis.
The three cells shown are from a single mother-infant pairing and contain, from left to right: fragments from a big toe of a mother, from other toes of a mother, and from toes and fingers of an infant. For each cell, the four fragments are labeled corresponding to the numerical order of their measurement.
Table 1.
Summary statistics from ICP-MS zinc concentration measurements of various groupings of nail clippings obtained from the MINI study.
Table 2.
Summary statistics from ICP-MS selenium concentration measurements of various groupings of nail clippings obtained from the MINI study.
Fig 2.
Energy spectrum from XRF measurement of a nail clipping.
Counts are provided as a function of energy (keV). The red line indicates the PyMca fit for various elements, while the green line represents the background continuum. Observed data points are given in black and are mostly obscured by the red fit line.
Table 3.
Relative standard deviations for the measurement of zinc in nail clippings when determining concentration using ICP-MS, concentration using the automated XRF system output, and the total area ratio (TAR) from energy spectrum analysis using XRF.
The table provides the mean, standard deviation (SD), standard deviation of the mean (SDOM), and median from both visit 1 and visit 2 measurements.
Table 4.
Relative standard deviations for the measurement of selenium in nail clippings when determining concentration using ICP-MS, concentration using the automated XRF system output, and the total area ratio (TAR) from energy spectrum analysis using XRF.
The table provides the mean, standard deviation (SD), standard deviation of the mean (SDOM), and median from both visit 1 and visit 2 measurements.
Fig 3.
XRF system output zinc concentration (μg/g) as a function of ICP-MS zinc concentration (μg/g) for nail clippings from visit 1 of the MINI study.
Uncertainty bars are provided for each data point. The unweighted best fit linear relationship between the variables is displayed as a blue dotted line and the weighted best fit linear relationship is displayed as an orange dotted line.
Fig 4.
XRF system output zinc concentration (μg/g) as a function of ICP-MS zinc concentration (μg/g) for nail clippings from visit 2 of the MINI study.
Uncertainty bars are provided for each data point. The unweighted best fit linear relationship between the variables is displayed as a blue dotted line and the weighted best fit linear relationship is displayed as an orange dotted line.
Fig 5.
Bland-Altman plot of the percentage difference between XRF and ICP-MS zinc concentration results as a function of ICP-MS zinc concentration from visit 1 of the MINI study.
The mean result is given as a bold horizontal line, with confidence interval limits given as lines above and below the mean.
Fig 6.
Bland-Altman plot of the percentage difference between XRF and ICP-MS zinc concentration results as a function of ICP-MS zinc concentration from visit 2 of the MINI study.
The mean result is given as a bold horizontal line, with confidence interval limits given as lines above and below the mean.
Fig 7.
XRF Total Area Ratio (TAR) zinc signal as a function of ICP-MS zinc concentration (μg/g) for nail clippings from visit 1 of the MINI study.
Uncertainty bars are provided for each data point. The unweighted best fit linear relationship between the variables is displayed as a blue dotted line and the weighted best fit linear relationship is displayed as an orange dotted line.
Fig 8.
XRF Total Area Ratio (TAR) zinc signal as a function of ICP-MS zinc concentration (μg/g) for nail clippings from visit 2 of the MINI study.
Uncertainty bars are provided for each data point. The unweighted best fit linear relationship between the variables is displayed as a blue dotted line and the weighted best fit linear relationship is displayed as an orange dotted line.
Fig 9.
XRF Total Area Ratio (TAR) selenium signal as a function of ICP-MS selenium concentration (μg/g) for nail clippings from visit 1 of the MINI study.
Uncertainty bars are provided for each data point. The unweighted best fit linear relationship between the variables is displayed as a blue dotted line and the weighted best fit linear relationship is displayed as an orange dotted line.
Fig 10.
XRF Total Area Ratio (TAR) selenium signal as a function of ICP-MS selenium concentration (μg/g) for nail clippings from visit 2 of the MINI study.
Uncertainty bars are provided for each data point. The unweighted best fit linear relationship between the variables is displayed as a blue dotted line and the weighted best fit linear relationship is displayed as an orange dotted line.
Table 5.
Linear equation of best fit slopes and y-intercepts for the unweighted data presented in Figs 3–10.
Parameter values and their uncertainties are provided in each case.