Measuring densities of solids and liquids using magnetic levitation: Fundamentals

Katherine A. Mirica, Sergey S. Shevkoplyas, Scott T. Phillips, Malancha Gupta, George M. Whitesides

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Abstract

This paper describes an analytical system that uses magnetic levitation to measure densities of solids and water-immiscible organic liquids with accuracies ranging from ±0.0002 to ±0.02 g/cm3, depending on the type of experiment. The technique is compatible with densities of 0.8-3 g/cm3 and is applicable to samples with volumes of 1 pL to 1 mL; the samples can be either spherical or irregular in shape. The method employs two permanent NdFeB magnets positioned with like poles facing one another - with the axis between the poles aligned with the gravitational field - and a container filled with paramagnetic medium (e.g., MnCl2 dissolved in water) placed between these magnets. Density measurements are obtained by placing the sample into the container and measuring the position of the sample relative to the bottom magnet. The balance of magnetic and gravitational forces determines the vertical position of the sample within the device; knowing this position makes it possible to calculate the density of the sample.

Original languageEnglish (US)
Pages (from-to)10049-10058
Number of pages10
JournalJournal of the American Chemical Society
Volume131
Issue number29
DOIs
Publication statusPublished - Jul 29 2009

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All Science Journal Classification (ASJC) codes

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

Cite this

Mirica, K. A., Shevkoplyas, S. S., Phillips, S. T., Gupta, M., & Whitesides, G. M. (2009). Measuring densities of solids and liquids using magnetic levitation: Fundamentals. Journal of the American Chemical Society, 131(29), 10049-10058. https://doi.org/10.1021/ja900920s