Cobalt detection

A simple and rapid test for cobalt in leguminous plants has been developed that Spanish and Venezuelan chemists claim could provide an alternative to more expensive methods.

Cobalt is an essential element for leguminous plants such as peas and beans, but may be harmful to other species, which is why its determination is important for the management of polluted areas. A number of methods currently exist to test for cobalt, but they tend to rely on relatively expensive and sophisticated techniques such as atomic absorption spectroscopy. A study published in Phytochemical Analysis¹ investigated whether ion chromatography coupled to luminol-based chemiluminescence detection could provide a simpler alternative.

Luminol emits a bright blue light when it reacts with a strong oxidant; this reaction is catalysed by metal cations, including cobalt. But as the plants may contain other metals ion chromatography is necessary to separate the resulting solution and identify cobalt.

According to the study, well‑resolved chromatographic peaks were obtained. The height and area showed linear dependences with the cobalt concentration, which were used to quantify the heavy metal. The method was reported to take less than 12 minutes to complete.

The study concluded that the method was suitable as a simple and rapid alternative for the determination of cobalt in plant tissue with detection limits comparable to those obtained with more sophisticated and expensive analytical equipments.

1. J.A. Murillo Pulgarín, L.F. García Bermejo and A.C. Durán, Phytochemical Analysis (in press).

This story originally appeared in The Column. Click here to view that issue.