Method of preserving biological tissue specimens and method of infrared spectroscopic analysis which avoids the effects of polymorphs

A method for preserving a tissue specimen to be subject to infrared spectroscopy for detecting a malignant or premalignant anomaly, comprising:

• obtaining said tissue specimen including cells, said specimen being in generally wet, fresh specimen form characteristic of tissue that has been freshly removed from a living body,
• within about an hour of exposure to above freezing temperature applying an inorganic salt based infrared spectral preservative by soaking said specimen in an inorganic salt solution wherein the salt is selected from the group consisting of sodium halide and potassium halide, said solution having a salt concentration in the range of about 0.5 to 3.0% by weight, removing excess liquid from the specimen by centrifuging, placing the damp specimen with excess liquid removed on an infrared optical window and drying the specimen on the window by a flow of room temperature air so as to dry the specimen and form a solid film of salt crystal over the specimen within about 2 minutes, thereby obtaining a dried, spectrally-preserved specimen which substantially maintains the spectral characteristics of said fresh specimen in a spectral range of interest after exposure to above freezing temperature.