FLOW-REVERSAL INJECTION-ANALYSIS FOR IMPROVED STRIPPING VOLTAMMETRY

The use of repeated reversals of the flow direction offers significant improvements in the sensitivity of flow‐injection stripping voltammetric measurements. The multiple passage of the same sample plug over the working electrode addresses the time restriction of conventional flow‐injection stripping measurements. The plating efficiency and the resulting stripping peak currents are greatly enhanced. The flow‐reversal stripping response of a mercury‐coated carbon fiber electrode is evaluated with respect to delay time, number of flow reversals, sample volume, and other variables. The prolonged deposition period obtained with 10 flow oscillations gives a 13‐fold enhancement of the response and a detection limit of 7 × 10−9 M (compared with 9 × 10−8 M for conventional flow‐injection operation). The stripping measurements are supported by amperometric monitoring of the current during the passage of the sample plug. Copyright © 1990 VCH Publishers, Inc.