Mass spectrometry is an analytical technique that is used to quantify known materials, identify unknown compounds, and elucidate structural and physical properties of molecules. Scientists use mass spectrometry to weigh molecules. Molecules are extremely small and cannot be weighed in the traditional sense on a scale. To give you an estimate of the size of a molecule of water, it would take approximately 60,000,000,000,000,000,000,000 water molecules to fill a tablespoon. We refer to the weight of a molecule as its mass which can be measured “electronically” by using a mass spectrometer. Mass spectrometers are used in many laboratories throughout the world to analyze thousands of compounds such as those present in our bodies, our environment, our medicines, manufactured materials, foods, poisons, and criminal evidence. Mass spectrometry is associated with very high speed, sensitivity, and specificity. This means that compounds of interest can rapidly be identified at very low concentrations in chemically complex mixtures. Mass spectrometry provides valuable information to a wide range of professionals including chemists, biologists, physicians, and astronomers.