Heterogeneous Example: Plastic Versus Glass Containers
Filtering can affect the ratio of La to Lb lines observed in the XRF spectrum for a heavy element such as mercury. Materials such as glass placed between the material being analyzed and the instrument can filter the X-Ray radiation from the instrument in a selective manner, such that some transitions are more strongly stimulated than others, resulting in a skewing of emission line intensities. This can provide an important clue that the element in question is buried, particularly for Group 6 metals such as lead. The example below illustrates this with mercury in a non-absorbing polyethylene bag versus glass vial.