Surface Enhanced Raman Determination of Headspace Sampled Dimethyl Trisulfide
Alam, Md Nure
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Cyanide is a toxin with many natural and industrial sources. Among several cyanide antidotes dimethyl trisulfide (DMTS) is one of the current promising candidates under investigation. Surface Enhanced Raman Spectroscopy (SERS) is a sensitive, cost effective method that has long term potential for multiplexed, portable sensing. In this research, experiments were carried out to compare three different approaches to sampling DMTS from ethanolic solutions: drop-coating, immersion, and headspace sampling. The SERS experiments in all media show promising sensitivity with detectable signals at 5 micromolar concentrations of DMTS in ethanol. Problems in the reproducibility of signals in the headspace sampling led to the observation that condensation on the sample cell windows and sensor was a problem. A proof of principle experiment using resistive heating to warm the sampling window was successful in removing and preventing condensation. Experiments were also carried out in which DMTS was reduced to produce more volatile products that could be detected more rapidly from the headspace than DMTS. In these experiments, SERS peaks were observed to grow in more rapidly than had been observed from headspace sampling above ethanolic DMTS solutions. Specifically, SERS peaks from reduction products were observed within a minute following the initiation of reaction.