Analytical note Fast sequential multi-element determination of Ca, Mg, K, Cu, Fe, Mn and Zn for foliar diagnosis using high-resolution continuum source flame atomic absorption spectrometry: Feasibility of secondary lines, side pixel registration and least-squares background correction☆ Silvana Ruella de Oliveira, Jorge Luiz Raposo Jr., José Anchieta Gomes Neto ⁎ São Paulo State University – Unesp, Analytical Chemistry Department, P.O. Box 355, 14801-970 Araraquara – SP, Brazil abstract article info Article history: Received 10 October 2008 Accepted 23 March 2009 Available online 5 April 2009 Keywords: Foliar diagnosis Sugar-cane Side pixel registration High-resolution continuum source flame atomic absorption spectrometry The fast sequential multi-element determination of Ca, Mg, K, Cu, Fe, Mn and Zn in plant tissues by high- resolution continuum source flame atomic absorption spectrometry is proposed. For this, the main lines for Cu (324.754 nm), Fe (248.327 nm), Mn (279.482 nm) and Zn (213.857 nm) were selected, and the secondary lines for Ca (239.856 nm), Mg (202.582 nm) and K (404.414 nm) were evaluated. The side pixel registration approach was studied to reduce sensitivity and extend the linear working range for Mg by measuring at wings (202.576 nm; 202.577 nm; 202.578 nm; 202.580 nm; 202.585 nm; 202.586 nm; 202.587 nm; 202.588 nm) of the secondary line. The interference caused by NO bands on Zn at 213.857 nm was removed using the least-squares background correction. Using the main lines for Cu, Fe, Mn and Zn, secondary lines for Ca and K, and line wing at 202.588 nm for Mg, and 5 mL min -1 sample flow-rate, calibration curves in the 0.1–0.5 mg L -1 Cu, 0.5–4.0 mg L -1 Fe, 0.5–4.0 mg L -1 Mn, 0.2–1.0 mg L -1 Zn, 10.0–100.0 mg L -1 Ca, 5.0– 40.0 mg L -1 Mg and 50.0–250.0 mg L -1 K ranges were consistently obtained. Accuracy and precision were evaluated after analysis of five plant standard reference materials. Results were in agreement at a 95% confidence level (paired t-test) with certified values. The proposed method was applied to digests of sugar- cane leaves and results were close to those obtained by line-source flame atomic absorption spectrometry. Recoveries of Ca, Mg, K, Cu, Fe, Mn and Zn in the 89–103%, 84–107%, 87–103%, 85–105%, 92–106%, 91–114%, 96–114% intervals, respectively, were obtained. The limits of detectionwere 0.6 mg L -1 Ca, 0.4 mg L -1 Mg, 0.4 mg L -1 K, 7.7 μg L -1 Cu, 7.7 μg L -1 Fe, 1.5 μg L -1 Mn and 5.9 μg L -1 Zn. © 2009 Elsevier B.V. All rights reserved. 1. Introduction Foliar diagnosis is an efficient tool to evaluate not only the nutritional state of plants, but also to correct nutrient deficiencies, optimize crop production and evaluate fertilizer requirements. Ca, Mg, K, Cu, Fe, Mn and Zn are among the macro- and micronutrients most frequently required in foliar analysis [1,2]. Foliar analysis for Ca, Mg, K, Cu, Fe, Mn and Zn is frequently carried out by line-source flame atomic absorption spectrometry (LS FAAS) [3,4] or inductively coupled plasma optical emission spectrometry (ICP OES) [5–7] techniques. For routine laboratories devoted to large scale analyses, the fast sequential multi-element determination is particularly helpful because time and analytical costs may be significantly reduced. The applicability of the LS FAAS has been further extended with the development of high-resolution continuum source flame atomic absorption spectrometry (HR-CS FAAS) [8]. In HR-CS FAAS a high-intensity xenon short-arc lamp as continuum radiation source, a high-resolution double Echelle monochromator and a CCD array detector provide a resolution of ~2 pm per pixel. The possibility of using the main and secondary analytical lines [9], applying the wavelength-selected absorbance (WSA) over the line core including part of the line wings to enhance sensitivity [10], measuring at wings of line core (side pixel registration) to extend the linear working range [10,11], and least-squares background correction (LSBC), for which the software is capable of storing reference spectra and of subtracting such spectra from the spectra recorded for a sample, using a least squares algorithm [12], make a particular innovation of this new approach. The aim of this work was to develop a simple and robust method for the fast sequential multi-element determination of Ca, Mg, K, Cu, Fe, Mn and Zn in plants by HR-CS FAAS using new features, useful to overcome limitations of conventional LS FAAS such as LSBC and side pixel registration. Spectrochimica Acta Part B 64 (2009) 593–596 ☆ This paper was presented at the 10th Rio Symposium on Atomic Spectrometry, held in Salvador-Bahia, Brazil, 7–12 September 2008, and is published in the special issue of Spectrochimica Acta Part B, dedicated to that conference. ⁎ Corresponding author. Tel.: +55 16 33016611; fax: +55 16 33016692. E-mail address: anchieta@iq.unesp.br (J.A. Gomes Neto). 0584-8547/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.sab.2009.03.016 Contents lists available at ScienceDirect Spectrochimica Acta Part B journal homepage: www.elsevier.com/locate/sab