ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Coupling of microwave induced plasma optical emission spectrometry with HPLC separation for speciation analysis of Cr(III)/Cr(VI)

G. Heltai, B. Fehér, and M. Horváth

Department of Chemistry and Biochemistry, Szent István University, Gödöllö, H-2103, Hungary

E-mail: heltai.gyorgy@mkk.szie.hu

Received: 9 November 2006  Revised: 10 May 2007  Accepted: 6 June 2007

Abstract: Feasibility and limitations of direct coupling of high performance liquid chromatographic (HPLC) separation to microwave induced plasma (MIP)-optical emission spectrometry (OES) for elementspecific detection was tested and compared to inductively coupled plasma (ICP)-optical emission spectrometric detection on the basis of the Cr(III)/Cr(VI) speciation analysis of water samples. Coupling was performed by a hydraulic high pressure nebulizer (HHPN) radiative-heating/watercooling interface which provides about 20 % and 80 % aerosol yield in the case of helium and argon carrier gases, respectively. Desolvation efficiency of aqueous solutions was approximately 80 %. Applying the ion-pair HPLC separation, the organic eluents and reagents in the MIP cause a 50–75 % signal suppression for Cr(VI) and 25–50 % for Cr(III). In a pure aqueous solution the MIP Cr(VI) signal was by 20 % lower than that of Cr(III). These effects were lower using the ICP source, but they cannot be neglected. Easily ionizable matrix elements (Na, Ca) can cause 70 % signal suppression in the MIP, and 20 % in the ICP. Therefore, species dependent calibration is required in both cases. In the case of HPLC detection by MIP-OES, the detection limit was 13 ng for Cr(III), and 18 ng for Cr(VI). Using the ICP-OES detection, the detection limit was 0.2 ng for Cr (III) and 0.4 ng for Cr (VI). The linear dynamic ranges in both cases were two orders of magnitude.

Keywords: speciation analysis - MIP-OES - ICP-OES - HPLC - Cr(III)/Cr(VI) separation

Full paper is available at www.springerlink.com.

DOI: 10.2478/s11696-007-0059-7

Chemical Papers 61 (6) 438–445 (2007)