Reactive blood gases such as hydrogen sulfide, methyl mercaptan, and hydrogen cyanide are naturally present in blood at trace levels. At higher concentrations these blood gases become toxic. Direct detection of the blood gases themselves is challenging because their signals are often masked by those of their reaction partners and the more abundant components of the complex matrix in which they reside. Here we overcome this challenge by separating the gas detection cell from the reaction cell. The two cells share a common well-sealed headspace. The volatile blood gases partition out of the reaction matrix into the headspace, and out of the headspace into the detection solution, where they undergo chemical reactions tailored for trapping and detecting the blood gas of interest. The kinetics of reactions can be followed by simultaneously monitoring spectral changes in both cells and by gas phase monitoring (for example by SERS) of the headspace. In preliminary tests of the system, we have generated mercaptans by reducing polysulfides with tris(2-carboxyethyl)phosphine (TCEP) in the reaction cell. Mercaptans are highly toxic: appropriate precautions were taken to ensure safety. We present data showing proof-of-principle of the system: the mercaptan gases generated in the sealed reaction cell successfully traverse the headspace and are trapped by reaction with Ellman’s reagent (DTNB) in the detection cell. The kinetics of this model reaction has been followed with UV visible spectrometry. By separating the detection and reaction chemistry, this sealed dual-cell provides a cost-effective and flexible apparatus for studying the kinetics of blood gas reactions: and trapping and detecting the blood gases involved.

Dual cell system for in vitro studies of toxic blood gases

256th National Meeting (2018)

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