MICROCHEMICAL JOURNAL 54, 184–194 (1996) ARTICLE NO. 0094 Determination of Arsenic Species by High-Performance Liquid Chromatography–Hydride Generation–(Ultrasonic Nebulizer)– Atomic Fluorescence Spectrometry ZOLTA ´ N MESTER,A ´ GNES WOLLER, AND PE ´ TER FODOR 1 Department of Chemistry and Biochemistry, University of Horticulture and Food Industry, 29-35 Villa ´nyi, H-1114 Budapest, Hungary A technique to determine four species of arsenic (As III , As V , dimethylarsinic (DMAs), and monomethylarsonic (MMAs) acids) where high-performance liquid chromatography was coupled to an atomic fluorescence spectrometer using an ultrasonic nebulizer as an interface has been further improved by the use of hydride generation. The effect of hydride conditions on signal intensities has been investigated. The detection limits for As III , As V , DMAs, and MMAs were 2.5, 6, 3.2, and 2 ng, respectively (at 250 mm 3 volume injected). The linearity for all four arsenic species were in the range 25–1000 ng.  1996 Academic Press, Inc. INTRODUCTION Speciation studies has become more and more popular in the past decades for a large scientific community. Because these techniques address only a fraction of the total metal present in the sample therefore requires ultra-sensitive methods (ng/liter range in water and ng/g in soil matrices). This problem has been solved most frequently by coupling a powerful separation technique (usually chromatography) and a sensitive, selective detection system, e.g., atomic absorption spectrometry (AAS), inductively coupled plasma – mass spectrometry (ICP-MS), inductively coupled plasma – atomic emission spectrometry (ICP-AES), etc. These techniques are usually called ‘‘hyphen- ated’’ techniques. A very important field of speciation studies today is arsenic speciation. A possible solution for the speciation of four toxicologically important arsenic species (As III , As V , dimethylarsinic (DMAs), and monomethylarsonic (MMAs) acids) has been published in our previous paper (1 ), where a C 18 Rutin column coupled to a high-performance liquid chromatography pump has been used for the separation; for detection a hydrogen diffusion-flame-based atomic fluorescence spectrometer (AFS) has been coupled to the chromatographic system. Desolvation and nebulization needed for the AFS tech- nique has been carried out by an ultrasonic nebulizer (USN). The mentioned hyphen- ated technique has shown relatively good separation for the investigated species, although the limit of detection (LOD) was too high for the analyses of biological and environmental samples. The analytical potential of hydride generation (HG) was first reported by Holak (2 ) in 1969; since then the technique has become a widely accepted method for determining elements which form volatile hydrides. These elements are 1 To whom correspondence should be addressed. 184 0026-265X/96 $18.00 Copyright  1996 by Academic Press, Inc. All rights of reproduction in any form reserved.