This category of metadata seems pretty straightforward if you think about the analysis of one single analyte for its solution concentration, however the metadata here must be comprehensive enough to cover all analysis possibilities.  Please let This email address is being protected from spambots. You need JavaScript enabled to view it. know there are any additional metadata items needed. (names update 2-12-15)

• substance: a discrete chemical species identified by its InChI string [09-23-14]
• substance class: named group of chemical substances identified as a specific class by structure, use, size, or action determined in chemical analysis procedures [09-23-14] (e.g. PCB's, amino acids, PAH's, pharmaceuticals, heavy metals, enzymes, etc.)
• functional group: chemical test for an organic functional group [02-26-15]
• biological property: a property specific to a biological process [02-26-15]
  (e.g. biological activity, QSAR)
• chemical property: any property to due with a chemical reaction [02-26-15]
  ( e.g. heat of combustion, enthalpy of formation, toxicity, chemical stability, flammability, rate of reaction, etc.)
• physical property: measurement of a bulk (material) property, or characteristic substance property [02-26-15]
  (e.g. solubility, refractive index, electrical conductivity, color, thermal conductivity, etc. - anything other than concentration)
• analyzed form: a descriptive term to indicate the state of the analyte as it was measured (not the oxidation state) [09-23-14]
  (e.g. dissolved, labile, total, volatile, extractable, free, residual, etc.)