Chemists have developed a number of methods by which they can determine the kind of elements present in a material and the amount of each element present. Nuclear magnetic resonance (NMR), flame spectroscopy, and mass spectrometry are examples of elemental analysis. These methods have been improved to a point where concentrations of a few parts per million of an element or less can be detected with relative ease. Elemental analysis is valuable in environmental work to determine the presence of a contaminant or pollutant. As an example, the amount of lead in a paint chip can be determined by means of elemental analysis.