10.2 Ancillary Information to Aid Identity Confirmation

In this laboratory, no identification is made on the basis of only one form of evidence. In addition to a mass spectrum, an identity confirmation may be supported by:

• common physical properties (solubility, physical appearance, melting point, boiling point, density, etc) are consistent with structure.
• a library search result.
• the infrared spectrum; we can confirm identity by IR alone, of course, and IR is not generally required to confirm an identity by GC/MS. However, some compounds are difficult to discriminate by GC/MS (such as some isomers), and for these, IR is a powerful complimentary technique.
• GC retention time (or retention index) is consistent with structure.
• chemical reactivity is consistent with structure. This includes chemical color tests.
• microcrystalline examination results are consistent with structure. In this laboratory, a microscope with crossed polarizers is available for the examination of bifringence as well as crystal shape and pattern.