Optimizing the performance of a commercial electrochemical ethylene sensor via controlled ethylene generation in situ

Abstract

Ethylene, which regulates fruit ripening processes in some species, is a molecule of central interest to postharvest researchers and technologists. There is a need for a portable, inexpensive, accurate, and repeatable sensor for infield or storeroom measurements. To help ensure repeatable results, we developed a field calibration protocol for a portable electrochemical gas sensor that combines ethephon (2-chloroethylphosphonic acid) with a buffering agent to release a controlled amount of ethylene gas (1–4 μL/L). The ethephon reaction provides an economical source of standard gas for device calibration. This work addresses device selectivity issues through the use of an inline aqueous trap to remove polar volatile organics (50% reduction, as reported by an electrochemical sensor), interfering with the ethylene detection. A complementary gas chromatographic (GC) assay provided an independent validation of these results. A post-harvest study of ethylene production of apples as detected by the electrochemical sensor illustrates significant improvements in the accuracy and precision of these measurements.