Rapid assessment of the latent hazard posed by dissolved mercaptans within aqueous effluent.

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.

A chromatographic tool for preparing combinatorial quinone-thiol conjugate libraries.

Quinones are well established as key players in the production of reactive oxygen species within cellular environments. Many factors govern their cytotoxicity but most studies have been restricted to a few, core, derivatives. A new strategy for the in situ production of quinone derivatives has been developed such that libraries of diverse functionality can be rapidly created without recourse to extensive synthetic procedures. The approach relies upon nucleophilic addition by reduced thiol derivatives to the quinone core within a pre-culture assay mixture and provides a generic strategy that exploits the large reservoir of commercial thiols currently available. A readily accessible chromatographic method has been developed that allows the derivatisation process to be easily monitored and the purity of the resulting one pot preparation to be assessed. The viability of the combinatorial approach has been fully validated through comparison with a range of quinone-S-conjugates prepared using conventional bench synthesis. The latter have been fully characterised.