Future Prospects

The use of ultrasound as a sample preparation method for solid-liquid extraction is widespread in many laboratories and can be regarded as fast and effective. Extractions based on sonication have been employed for the isolation of weakly-bound organic compounds from solid samples such as soils, animal tissue, plants, etc., and are comparable to methods involving more intensive treatments (e.g., Soxhlet, accelerated solvent, etc.). However, ultrasound applied to solid-liquid extraction of inorganic analytes has rarely been attempted, perhaps owing to the inefficient sonochemical effects caused by most ultrasonic baths, which are more extended than probe-type sonicators. Ultrasound irradiation from high-inten sity ultrasonic processors opens the door to new perspectives, mainly concerning those analytes that are strongly-bound to the matrix. Thus, extraction of elements from solid samples is feasible under optimized sonication conditions, hence avoiding the more intensive treatments commonly employed for matrix decomposition (i.e. dry or wet ashing procedures). New possibilities of ultrasound lie in its use as selective extraction techniques for metal speciation in conjunction with the appropriate leaching reagents. Thus, ultrasound-accelerated sequential extraction schemes for metal partitioning in environmental solid samples (e.g. soil, sediment, sewage sludge) or selective extraction of physicochemical forms of elements constitute new sample preparation strategies which deserve further research.

Table 2 Percentage of metal extracted into the liquid phase of slurries prepared in an acidic diluent and subsequently homogenized

by sonication

Sample

Element and percentage ofextraction

Sonication system

Reference

Bovine liver

Cd (111 %)

Bath

1

Bovine liver

Mn (100%), Fe (72%)

Probe

2

Cabbage leave

Cd (89%), Pb (1 %)

Probe

3

Cabbage root

Cd (86%), Pb (1.5%)

Probe

3

Carbon

Cr (14%)

Probe

4

Carbon

Cu (69%), Cr (2%)

Probe

5

Lemon leaves

Cd (67%), Cu (88%), Mn (98%)

Bath

1

Orchard leaves

Cd (100%), Cu (88%), Pb (98%)

Bath

1

Oyster

Cd (99%), Pb (98%)

Bath

6

Prawns

Se (88%)

Bath

6

Rice flour

Cd (100%)

Bath

1

Sediment

Cr (30%)

Probe

4

Sediment

Cu (60%), Cr (10%)

Probe

5

Silica gel

As (60%), Cr (65%), Ni (77%)

Probe

7

Spinach

Cu (98%), Cr (74%)

Probe

5

Spinach

Mn (100%), Zn (74%), Fe (36%), Cu (100%)

Probe

2

Talc

As (59%), Cr (61 %), Ni (74%)

Probe

7

Tomato leaves

Mn (70%), Fe (70%), Cr (51 %)

Probe

2

Tomato leaves

Mn (92%)

Bath

1

Wheat flour

Mn (97%), Fe (88%)

Probe

2

1, Minami H etal. (1996). Spectrochimica Acta, PartB, 51: 211. 2, Miller-lhli NJ (1990) Fresenius Journal of Analytical Chemistry 337: 271; 3, Dobrowolski R and Mierzwa J (1993) Fresenius Journal ofAnalytical Chemistry 346: 1058. 4, Miller-lhli NJ (1994) Journal of Analytical Atomic Spectrometry 9:1129. 5, Miller-lhli NJ (1993) Fresenius Journal of Analytical Chemistry 345: 482.6, Mierzwa J etal. (1997) Analytical Science 13: 189. 7, Mierzwa J and Dhindsa HS (1988) Atomic Spectroscopy 19:6.

See also: III/Ultrasound-Assisted Metal Extractions.

Solar Panel Basics

Solar Panel Basics

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

Get My Free Ebook


Post a comment