ELECTRON-PROBE X-RAY MICROANALYSIS OF FROZEN-HYDRATED BIOLOGICAL SPECIMENS

  • 1 January 1977
    • journal article
    • research article
    • Vol. 79  (3) , 254-266
Abstract
A technique is described for preparing frozen-hydrated bulk samples of biological specimens for electron probe X-ray microanalysis. The method allows reproducible quantitative analyses to be made. Specimens are rapidly frozen, transferred to a vacuum evaporator, fractured under high vacuum at -180.degree. C and coated with 20 nm of Cr. Transferral to the cryostage a scanning EM is accomplished without exposure to the atmosphere and without the specimen temperature rising above -120.degree. C. Analyses are made at a temperature of -145.degree. C. Contamination by frost does not occur. Etching and charging of the specimen are eliminated. Specimen charging is related to temperature. It can be eliminated at low temperature by coating with C, Al or Cr but consistent elimination could only be achieved with Cr. The Cr coat does not appear to have an absorption effect on quantitative analysis. [Cockroach nerve chord and cricket malpighian tubules were prepared by this method.].

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