⁷LiOH solution — A suitable reagent to collect volcanic gas samples for NAA

Abstract

Commercially available⁷LiOH was used for collecting volcanic gas samples on the island of Vulcano, Southern Italy, to determine trace elements by NAA. The high γ-background activity, which is induced when NaOH solutions are used as collecting agents was avoided in this way. While several elements (Cl, Br, I, As) could be determined in the collected samples, activation products of impurities in⁷LiOH produced considerable γ-background and this prevented the determination of other trace elements. An ion-exchange procedure for reducing impurities in⁷LiOH solutions, in particular of Hg, Ta and W, was then developed and is described here. This procedure, supplemented by steps to eliminate interference from¹⁸F in the irradiated samples due to small amounts of⁶Li in the⁷LiOH employed will allow very sensitive determinations of further trace elements in volcanic gases.