Pulsed amperometric detection waveform with disposable thin-film platinum working electrodes in high performance liquid chromatography

A new pulsed amperometric waveform is described for electrochemical detection with microfabricated disposable platinum electrodes. Methanesulfonic acid is selected as an eluent and electrolyte for use with platinum working electrodes. The mode of separation is ion exclusion. The optimized conditions make it possible to achieve improved reproducibility not only for alcohols, aldehydes, sulfite, cyanide and sulfide but also for several new types of analytes, such as ketones and sulfoxides. Utilizing an optimized waveform, reproducible results are obtained with relative standard deviations (RSD) of 3.94% or less. A stable performance for up to 2 weeks could be demonstrated for the detection of alcohols during an uninterrupted use of a single disposable platinum electrode. Further improvements are achieved in overall analytical performance, for example, in limits of detection and calibration linearity. Improvement in detection limits comes mainly from a lower background noise. The calibration is linear over two to five orders of magnitude with correlation coefficients greater than 0.996 for all types of analytes.