X-ray microanalysis of organic thin sections in TEM using an UTW Si(Li) detector: comparison of quantification...

We compared Hall's peak to continuum ratio method with a peak ratio method in order to quantify light elements (C, N, and O) in organic specimens as a model for biological thin sections. X-ray spectra were recorded by an energy dispersive X-ray spectrometer equipped with an ultra thin window detector. Spectra were processed by means of a top-hat filter adapted to peak full-width half maximum. The peak intensities were measured by multiple least square fitting to reference spectra. For most elements of biological interest, theoretical and experimental k-factors were determined. Absorption correction was found to be important for quantitation of carbon, nitrogen, and oxygen. Boron was efficiently detected; however, quantitative analysis was not possible. We conclude from our experiments that the peak ratio method is more suitable for quantitation of elemental concentrations in biological thin sections than the peak to continuum method.