Which onsite analytical method is used specifically for metal detection?

The correct choice for onsite analytical methods used specifically for metal detection is X-Ray fluorescence (XRF). This technique is particularly effective for identifying and quantifying metals in various materials quickly and non-destructively. XRF works by directing X-rays at a material, causing the elements within it to emit secondary (or fluorescent) X-rays. By measuring the energy and intensity of these emitted X-rays, the method can determine the presence and concentration of metallic elements.

XRF is widely used in environmental assessments, hazardous waste management, and industrial hygiene, as it offers rapid results and can be utilized in field settings without sending samples to a laboratory. This makes it an invaluable tool for professionals needing to detect metals in soils, dust, and other materials on-site.

In contrast, other methods mentioned, like inductively coupled plasma (ICP), while effective for metal analysis, usually require sample preparation and are primarily suited for laboratory environments. Silica gel tube analysis focuses on gases and vapors, not metals, making it irrelevant for this question. Gas chromatography (GC) is primarily used for separating and analyzing compounds that can vaporize, which does not encompass metal detection either.