Flow injection square wave cathodic stripping voltammetric determination at a hanging mercury drop electrode of rapidly reduced compounds: Determination of diacetyl in wine as 2,3-dimethylquinoxaline Original Research Article

A flow injection square wave cathodic stripping voltammetric technique has been developed for the determination of organics and other determinands which are very rapidly reduced in the adsorbed state (such that they give very small or no signal at low square wave frequencies). Very short accumulation times are used, and the application of a high frequency square waveform allows large signals to be obtained with minimal interference from dissolved oxygen. A limit of detection of 1×10−8 M was obtained and up to 15 samples can be analysed per hour with a good precision (R.S.D.<2%). The technique has been applied to the determination of diacetyl in vino verdi and port wine after derivatisation off-line with o-phenylenediamine to form 2,3-dimethylquinoxaline (DMQ). The strategy which has been developed is adaptable to other rapidly reduced species by making minor adjustments to flow and measurement parameters.