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Sonication as a sample preparation method for elemental analysis.
Comprehensive Analytical Chemistry. Vol. XLI. New York: Elsevier B.V., 2003 Dec; 353-367
Chemical effects induced by ultrasonic energy in solution can be employed for sample preparation purposes. Ultrasound consists of pressure waves exceeding 18 kHz; acoustic waves into the gigahertz range can be experimentally generated by mechanical means. When imparted to solutions, ultrasonic energy causes acoustic cavitation, or bubble formation and subsequent implosion [1,2]. The collapse of bubbles created by ultrasonication (usually abbreviated to "sonication") of solutions generates extremely high local temperature and pressure gradients, conditions which have been employed extensively in sonochemistry [1-5]. On a timescale of (equivalent)10(-10) s, effective local energies and pressure gradients of (equivalent)1eV and (equivalent)10(4) atm, respectively, are generated as a result of bubble implosion [1-3]. Hence ultrasonic energy serves to create localized "hot spots" that form most readily at interfaces between phases, notably at junctions between solutions and solids. These energetic interfacial effects of ultrasonic energy can be easily observed in ultrasonic cleaners, which are used to remove oxide layers tarnishing jewelry. Concomitant with bubble collapse in aqueous solution is the generation of hydrogen peroxide and hydroxide radicals [6-8]. These highly oxidative species aid significantly in the use of ultrasound for analytical extraction purposes. Applications of ultrasonic extraction (UE) in sample preparation have shown considerable promise for speeding up and simplifying sample treatment procedures.
Ultrasonic-testing; Ultrasonics; Chemical-analysis; Oxides; Sampling-methods; Sampling; Analytical-methods
Book or book chapter
Research Tools and Approaches: Exposure Assessment Methods
Comprehensive Analytical Chemistry XLI
Page last reviewed: September 2, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division