A shipboard method for arsenic speciation using semi-automated hydride generation atomic fluorescence spectroscopy

The development of a semi-automated batch HG-AFS method for the shipboard determination of As(III), As(V), MMA and DMA is described. Procedures in the analytical sequence including addition of NaBH4 to samples, cooling and heating the U-trap used for pre-concentration and separation of the arsines, and logging the AFS output are automated. Overall control of the automated tasks into a logical analytical sequence is achieved using a commercially available data acquisition and control package, WORKBENCHMAC(TM). Further modifications required for the method to be adapted to shipboard use, including the use of a hydrogen generator, are also detailed. This method shows a number of advantages over a previously reported manual HG-AFS method including, shorter sample throughput time, increased precision and most significantly, ease of use under shipboard conditions. The semi-automated method was operated on the RSV Aurora Australis during a Southern Ocean voyage in March 1998. Arsenic measurements from a surface transect between 42 degrees and 55 degrees S along 141 degrees 30' E, are presented. Application of the method to more routine laboratory use is also discussed. (C) 2000 Elsevier Science B.V. All rights reserved.