Sample treatment in chromatography-based speciation of organometallic pollutants

• Published in: Journal of Chromatography A 2001-12, Vol.938 (1), p.211-224
• Main Authors: Gómez-Ariza, J.L, Morales, E, Giráldez, I, Sánchez-Rodas, D, Velasco, A
• Format: Article
• Language: English
• Subjects: Analysis methods; Analytical chemistry; Animal, plant and microbial ecology; Applied ecology; Applied sciences; Biological and medical sciences; Chemical and industrial products toxicology. Toxic occupational diseases; Chemistry; Chromatographic methods and physical methods associated with chromatography; Chromatography - methods; Ecotoxicology, biological effects of pollution; Environmental Pollutants - analysis; Enzymes - chemistry; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; General aspects; Hydrolysis; Medical sciences; Metals and various inorganic compounds; Natural water pollution; Organometallic compounds; Organometallic Compounds - analysis; Organotin compounds; Pollution; Toxicology; Water treatment and pollution
• ISSN: 0021-9673
• DOI: 10.1016/S0021-9673(01)01103-7

Speciation analysis is nowadays performed routinely in many laboratories to control the quality of the environment, food and health. Chemical speciation analyses generally include the study of different oxidation state of elements or individual organometallic compounds. The determination of the different chemical forms of elements is still an analytical challenge, since they are often unstable and concentrations in different matrices of interest are in the μg l −1 or even in the ng l −1 range (e.g., estuarine waters) or ng g −1 in sediments and biological tissues. For this reason, sensitive and selective analytical atomic techniques are being used as available detectors for speciation, generally coupled with chromatography for the time-resolved introduction of analytes into the atomic spectrometer. The complexity of these instrumental couplings has a straightforward consequence on the duration of the analysis, but sample preparation to separate and transfer the chemical species present in the sample into a solution to be accepted readily by a chromatographic column is the more critical step of total analysis, and demands considerable operator skills and time cost. Traditionally, liquid–liquid extraction has been employed for sample treatment with serious disadvantages, such as consumption, disposal and long-term exposure to organic solvent. In addition, they are usually cumbersome and time-consuming. Therefore, the introduction of new reagents such as sodium tetraethylborate for the simultaneous derivatization of several elements has been proposed. Other possibilities are based in the implementation of techniques for efficient and accelerated isolation of species from the sample matrix. This is the case for microwave-assisted extraction, solid-phase extraction and microextraction, supercritical fluid extraction or pressurized liquid extraction, which offer new possibilities in species treatment, and the advantages of a drastic reduction of the extraction time and the embodiment into on-line flow analysis systems. This new generation of treatment techniques constitutes a good choice as fast extraction methods for feasible species-selective analysis of organometallic compounds under the picogram level, that can be used for national regulatory agencies, governmental and industrial quality control laboratories, and consequently, for manufacturers of analytical instrumentation.