Identifying Blood with Scanning Electron Microscopy

 We’re not afraid of a little blood….

Blood Magnified with SEM-EDSOften our clients come to us when they need testing and know exactly what type of testing approach they would like to use. However, it is quite common that we are approached by clients that know they have some sort of problem or challenge but aren’t quite sure the best way to approach it–that is where our team excels.

Recently, we ran into one such project. A long term client of ours requested our help because their product, which was a metal blade, had a contaminant that looked like an extremely small spot of blood. They wanted our help confirming or refuting this suspicion. Our recommendation was to initiate a contamination analysis project use Scanning Electron Microscopy coupled with Energy Dispersive Spectroscopy to obtain images of the sample and look for the presence of blood cells.

Our JEOL SEM is able to capture incredible images at up to 650,000x magnification. It uses beams of electrons to produce the images rather than natural light, which is why it has such amazing magnification power. An Energy Dispersive Spectroscopy (EDS or EDX) detector can then be used to perform a spectroscopic analysis to determine the chemical elements that comprise the sample.  This combined technique is referred to as SEM/EDS or SEM/EDX.

Jonathan Angle
Jonny Angle, SEM-EDS Technician

Our microscopist, Jonny Angle, described this sample and image acquisition as one of the hardest he has worked on to date. Initially, the electron beam was compromising the sample area using normal operating conditions. The voltage had to be adjusted and reduced to achieve the fine line between a voltage that would produce a good image but not destroy the structural integrity of the sample. Ultimately, he was able to acquire a beautiful and telling image of blood cells that were readily identifiable by their shape and size.

Jonny then used the EDS to acquire information about the chemical composition of the sample area. The results were carbon, sodium, chlorine, iron, and potassium which supported the conclusion that the red contaminant was blood.

This project speaks to Jonny’s expertise with the SEM-EDS and our team’s creative problem solving approach. It also highlights the versatility of our team. We regularly analyze polymer, rubber, plastic, and metallic materials but we can also work on projects that have a biological component.

1 Comment


  1. Hello Dear Mr Jonny Angle.

    For a scientific publication in preparation involving identification of blood stains through Raman and other methods, I would be very interested to see what does an EDS spectrum of human blood look like. Do you have such spectrum already published in a scientific article, and if so can you send me its copy? Or do you have an EDS spectrum available that can be eventualy freely reproduced in my paper of course with your reference.

    Reply

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