Voltammetric determination of airborne 2-chloronitrobenzene using a recirculating absorbent vapour sampler

Abstract

A system designed to pre-concentrate atmospheric vapour samples into a recirculating absorbent and which is suitable for direct voltammetric analysis is described. A Meinhard nebuliser operates as a venturi pump to allow circulation and dispersion of the absorbent into a fine aerosol, suitable for efficient collection of vapour samples. The incoming gas phase drives the nebuliser from which the mixed aerosol-vapour sample is condensed in a length of glass tubing. The pre-concentrated sample is circulated through an electrochemical cell for voltammetric detection at a hanging mercury drop electrode. The optimum electrochemical conditions for the determination of test atmospheres containing 2-chloronitrobenzene at levels of 1.5–4.3 × 10^–4 g m^–3 for sampling periods of between 30 and 813 s at a flow-rate of 0.18 dm³ s^–1 are described.