The development of analytical techniques and methods in the measurement of xenobiotics in environmental and biological matrices: the case of metallic elements

R. Magarini | Spettroscopia Atomica, Rovetta (BG), Italy

Introduction. In 2025, it will be seventy years since Alan Walsh published his seminal work (1) in 1955, which marked the birth of a new instrumental analysis technique, atomic absorption (AAS). Boris L'vov's subsequent work (2) dates back to 1961, introducing the graphite furnace as an atomizer for AAS, and GF-AAS is still one of the techniques of choice for the determination of trace elements, a field that has been strongly influenced by it.
The 1960s are viewed as a period in which inductively coupled plasma (Greenfield and Fassel et al.) was developed for emission spectroscopy analysis. But it was in 1980 that the combination of ICP and mass spectrometry (3) led to the introduction of ICP-MS as an instrumental analysis technique (ICP-MS). This made available a multi-element technique that allows the determination of metallic elements at ppb/ppt/ppq levels, which is finally the answer to the changing needs of occupational medicine, which has meanwhile shifted from a clinical discipline to an eminently preventive one.
Objectives. The aim is to provide an overview of the possibilities offered by atomic spectroscopy techniques (GF-AAS and ICP-MS in particular) for the determination of metallic elements in environmental and biological matrices, both quantitatively and semi-quantitatively, as well as for the discrimination of possible species (isotopes, ionic and/or molecular form) or size (nanoparticles).
Methods. Preference was given to analytical procedures requiring simple sample dilution in order to optimize analytical speed and reduce the risk of contamination. For example, the determination of blood Pb with GF-AAS involves 10x dilution with a matrix modifier, injection onto an Lvov platform, and calibration using the addition method. Multi-element analysis with ICP-MS of the urine of exposed subjects involves dilution with water, calibration using the addition method, and the use of the reaction and/or collision cell, depending on the elements to be determined. Hg speciation in whole blood with HPLC-ICPMS is performed after dilution with water and cysteine, and elution with a cysteine-based mobile phase.
Results. Some results obtained in the analysis of environmental and biological matrices using atomic spectroscopy techniques (GF-AAS and ICPMS, in particular) commonly used in laboratories involved in the determination of metallic elements are presented. The determination of methyl-Hg in whole blood by LC-ICPMS has also been optimized at the chromatographic and spectrometric level.
The analyses were validated with certified reference materials, when available, and the unavailability of good quality certified materials was one of the main problems encountered in the development of a method for the determination of metal NPs (Cr and Ni) in the urine of workers professionally exposed to welding fumes.
Conclusion. The report will present a historical and technological overview of the main developments in analytical techniques for the determination of trace metal elements in environmental and biological matrices, with a focus on currently available techniques and those under development.