The presence of mercaptans (RSH) can usually be detected by their inherent noxious odour but there is a need to quantify the concentration within effluent and hence allow an assessment of the latent hazard to be made prior to disposal. The versatility of using naphthoquinone as a rapid derivatising agent through which to trap such species has been evaluated. The quinone moiety provides a label that can be quantified using colorimetric, electrochemical and chromatographic means and offers a significant advantage over conventional thiol labelling agents. The analytical characteristics of each approach have been investigated and the selectivity, sensitivity and applicability of the reaction system critically assessed for a range of model compounds. The naphthoquinone system has a detection limit in the low micromolar range with little interference from other components common to discharge water with 96% recovery of mercaptopropionate. The reaction to sulfide (HS-) has also been assessed and a disparity in response between the detection methods observed and a possible reaction pathway outlined.
Villalba, MM., Litchfield, VJ., Smith, RB., Franklin, AM., Lawrence, NS., & Davis, J. (2008). Rapid assessment of the latent hazard posed by dissolved mercaptans within aqueous effluent. Journal of Hazardous Materials, 154(1-3), 444-450. https://doi.org/10.1016/j.jhazmat.2007.10.062