Straw Cell

What is it about?

Low-cost tube-type sample cells for X-ray spectroscopy of solutions, sols, and gels were made from plastic straws. Energy-dispersive X-ray fluorescence (XRF) experiments showed that the X-ray transparency of the straw cells is ~50% superior to that of quartz capillary cells for 6‒7 keV XRF and is almost uniform over the entire range, allowing its use for position-dependent measurements. Wavelength-dispersive XRF experiments showed that the difference in the surface curvature between the straw cells and pellet samples leads to an apparent ~1.5 eV shift of the Fe Kβ1,3 peak; however, chemical effects of Fe Kβ1,3 spectra can be studied if all the samples (including standards) are evenly set in the straw cells. Additionally, the application of the straw cell in studying precipitation band formation in gels was shown on two gel samples containing 0.004 M [Fe(CN)6]3-/[Fe(CN)6]2- in 2 mass% κ-carrageenan and 0.040 M Fe2+/Fe3+ in 1 mass% agarose, respectively.

Featured Image

Photo by Danielle MacInnes on Unsplash

Photo by Danielle MacInnes on Unsplash

Why is it important?

In this study, we propose tube-type cells as an alternative to quartz capillaries for X-ray analyses of solutions, sols, gels, and reaction-diffusion (RD) processes in hydro-gels. The alternative cells (straw cells) are made of 4 mm-wide plastic straws. Compared to quartz capillary cells, the straw cells are much less fragile, allow for easy introduction of viscous samples into them, show higher and uniform X-ray transparency, and can be made at a much lower cost. Finally, the reusability of the plastic straws might contribute to alleviating the burden of plastic debris in the environment.

Perspectives