Analytica Chimica Acta 424 (2000) 211–222 Speciation of organoarsenic compounds by polypyrrole-coated capillary in-tube solid phase microextraction coupled with liquid chromatography/electrospray ionization mass spectrometry Jingcun Wu, Zoltán Mester, Janusz Pawliszyn ∗ Department of Chemistry, University of Waterloo, Waterloo, Ont., Canada N2L 3G1 Received 18 May 2000; received in revised form 16 August 2000; accepted 16 August 2000 Abstract In-tube solid phase microextraction (SPME) is an on-line extraction technique for compounds in aqueous samples, in which analytes are extracted and concentrated from the sample directly into a coated capillary by repeated aspirate/dispense steps. In this paper, a polypyrrole (PPY) coated capillary and several commercially available capillaries (used for GC separation) were used to examine their extraction efficiencies to the organoarsenic compounds studied. Compared with commercial capillaries that were currently used for in-tube SPME, the PPY coated capillary has shown better extraction efficiency to most of the compounds studied, especially to the anionic species, due to the inherent multi-functionality of pyrrole polymer. For the first time, this PPY coated capillary has been used for automated in-tube SPME and speciation of organoarsenic species in aqueous samples when coupled with liquid chromatography-electrospray ionization mass spectrometry (LC-ESI-MS). Organoarsenic compounds in water samples and arsenobetaine in a certified reference material (DORM-2) were analyzed by this method. © 2000 Elsevier Science B.V. All rights reserved. Keywords: Polypyrrole; Solid phase microextraction (SPME); Speciation; Organoarsenic compounds; HPLC; ESI-MS 1. Introduction Recently, chemical speciation has obtained in- creasing interest since the toxicity and mobility of an element, and its biological and environmental im- portance are highly related to the chemical forms of the element in the sample. It is well known that ar- senite (As(III)) and arsenate (As(V)) are more toxic than monomethylarsonic acid (MMAs) and dimethy- larsinic acid (DMAs), while arsenobetaine (AsB) and arsenocholine (AsC) are relatively non-toxic [1,2]. ∗ Corresponding author. Tel.: +1-5198851211; fax: +1-5197460435. E-mail address: janusz@uwaterloo.ca (J. Pawliszyn). For the speciation of arsenic compounds, the coupling of chromatographic separation with element-specific spectrometric detection has proven to be useful. In particular, high performance liquid chromatography (HPLC) with inductively coupled plasma mass spec- trometry (ICP-MS) [3–9], atomic absorption spec- trophotometry (AAS) [10,11], inductively coupled plasma atomic emission spectrometry (ICP-AES) [12], and atomic fluorescence spectrometry (AFS) [13,14] have played important roles in arsenic speci- ation studies. Although these techniques, especially HPLC-ICP-MS, offer the advantages of high selec- tivity and sensitivity, chemical species identification is based entirely on the separation condition (reten- tion time) since only elemental information is pro- 0003-2670/00/$ – see front matter © 2000 Elsevier Science B.V. All rights reserved. PII:S0003-2670(00)01153-3