A method of preparing and using gelatine blocks as standards for quantitative X-ray microanalysis of bulk hydrated tissue is described. Each series of standards had several constant and one variable element. The average deviations in the X-ray counts of the constant elements from the series means were used to correct the recorded count of the variable element in each block. This led to an improved linear relationship between X-ray counts and concentration. The elements tested, sodium, phosphorus, and potassium, were chosen as representatives of different parts of the X-ray spectrum. Sodium cannot be measured reliably below 50 mmol kg-1 wet weight, although phosphorus and potassium can be detected at concentrations of 5 mmol kg-1 wet weight. It is argued that this sensitivity of analysis is sufficient for studying electrolyte changes in certain pathological processes.
Electron Probe Microanalysis Freezing