XRF testing is commonly used to detect lead in paint. Which technology does this involve?

XRF testing is commonly used to detect lead in paint. Which technology does this involve?

• A. Colorimetry
• B. Gas chromatography
• C. X-ray fluorescence
• D. Mass spectrometry

Answer: (C)

This question tests how XRF testing identifies lead in paint by using X-ray fluorescence. When a material is irradiated with high-energy X-rays, the atoms inside become excited and eject inner-shell electrons. As electrons from higher shells fill those vacancies, they emit X-ray photons with energies unique to each element. Detecting these characteristic X-rays reveals whether lead is present and estimates its concentration. This method is non-destructive, rapid, and well-suited for surveying painted surfaces in lead inspections, which is why X-ray fluorescence is widely used for lead detection in paint. Other techniques listed serve different purposes: colorimetry measures color changes rather than elemental content, gas chromatography separates and detects volatile or semi-volatile compounds, and mass spectrometry analyzes molecular masses after sample preparation—none are as directly suited to identifying elemental lead in paints as XRF.

This question tests how XRF testing identifies lead in paint by using X-ray fluorescence. When a material is irradiated with high-energy X-rays, the atoms inside become excited and eject inner-shell electrons. As electrons from higher shells fill those vacancies, they emit X-ray photons with energies unique to each element. Detecting these characteristic X-rays reveals whether lead is present and estimates its concentration. This method is non-destructive, rapid, and well-suited for surveying painted surfaces in lead inspections, which is why X-ray fluorescence is widely used for lead detection in paint. Other techniques listed serve different purposes: colorimetry measures color changes rather than elemental content, gas chromatography separates and detects volatile or semi-volatile compounds, and mass spectrometry analyzes molecular masses after sample preparation—none are as directly suited to identifying elemental lead in paints as XRF.