Twenty five years ago low-resolution line source atomic absorption spectrometry (LR-LS AAS), although in full maturity and providing high sensitivity and selectivity through the element-specific line radiation source, had limited versatility and low speed of analysis being known as a single-element technique. To face the challenges of the inductively coupled plasma optical emission spectrometry (ICP-OES), which imposed itself as a fast multielemental technique due to the charged-coupled device (CCD) technology, the need to increase the versatility of AAS with respect to line selection, background correction and higher analysis speed became imperative. Thus, in the mid-1990s a research group led by Becker-Ross from the Institute for Analytical Sciences, Berlin, Germany, designed and built the first instrument for high-resolution continuous source atomic absorption spectrometry (HR-CS AAS), in which all components were optimized for the novel approach [1–3]. The new concept instrument has been for several years commercially available for both flame (HR-CS FAAS) and graphite furnace (HR-CS GFAAS) atomization. The relevant advantages of HR-CS AAS over LR-LS AAS are : (i) use of just one source for all elements; (ii) visualization of the environment of the analytical line permitting superior background correction by simultaneous measurement of atomic and background absorption; (iii) fast-sequential multielemental determination using atomic lines or molecular bands (changing lines and parameters optimization only takes a few seconds); (iv) correction of the fine-structured background using a reference spectrum. The extremely well acceptance of HR-CS AAS instrument after its introduction on the market together with the versatility of the analytical applications was reflected in several reviews [5–11]. Both approaches of the technique, using either flame or electrothermal atomization, were used for multielemental determination in various complex matrices. Thus, HR-CS GFAAS was mentioned for elemental determination in food after acidic digestion or extraction in tetramethylammonium hydroxide [12–14], airborne particulates [15–18], biological (beans and grain) samples using direct solid sampling [19–21], fertilizer by slurry sampling , crude oil [23–26], biodiesel  and in whole blood directly in diluted/undiluted samples .
At the same time, HR-CS FAAS was used for multielemental determination in vegetable oil as microemulsion , plant tissues after mineralization [30, 31], dairy products by slurry sampling , pewter alloys after digestion in HCl solution , lubricating oil after acid digestion, oil-in water emulsification and dilution in kerosene [34–36], and soil extracts .
The introduction of the continuum source and high-resolution monochromator has opened the door to monitor non-metals (P, S, F, Br, N, etc.) with sensitive lines in the far UV, not accessible for LS-AAS. Thus, the molecular absorption spectrometry (HR-CS MAS) can overcome this barrier by measuring the absorption of a line within the band spectra of a diatomic molecular radical (PO, CS, SH, AlF, SrF, GaF, AlBr, CaBr, NO, etc.) stable in flame or graphite furnace at the atomizer temperature [9, 21, 38–49].
This paper reports on the validation of an analytical method for the fast-sequential determination of several hazardous/priority hazardous metals (Ag, Cd, Cr, Co, Cu, Ni, Pb and Zn) in soil based on the HR-CS FAAS. The soil samples were subjected to microwave assisted digestion in aqua regia according to ISO 11466 – 1999. Validation was conducted according to the method-performance study to estimate the performance characteristics of the new method (limit of detection, limit of quantification, precision and accuracy [50, 51]. Furthermore, the Bland and Altman statistical method was used in analyzing the agreement between the proposed assay and inductively coupled plasma optical emission spectrometry as standardized method for the multielemental determination in soil .
The paper is important for the analytical practice because currently the standardized methods for soil analysis by atomic absorption spectrometry are LR-LS FAAS and GFAAS . On the other hand, ISO/IEC 17025–2005 and the Programme of Association of Official Analytical Chemistry demand the fit-for-purpose validation of the new techniques/assays before use.