Quantitative analysis of electron energy-loss spectra from ultrathin-sectioned biological material. II. The application of bio-standards for quantitative analysis.

Electron energy-loss spectroscopy (EELS) has been used to determine elemental concentrations in biological specimens, consisting of ultrathin-sectioned cells and tissues. Chelex100-based Ca- and Fe Bio-standards are used for elemental quantification to establish iron and calcium concentrations. These Bio-standards, as well as the biological materials, are treated in a standard EM procedure such that 'known' and 'unknown' sites are located in one cross-section. Uncertainties and variabilities present in the equations for calculating the concentration in the 'unknown' site (determined by comparing simplex-fitted EEL spectra from Bio-standards with those from tissue) are outlined in two examples. Using an H+ Bio-standard, the matrix composition of such biological cell material is analysed, leading to values which approach each other closely. Quantitative EELS, using Chelex100-based Bio-standards, is advocated.