Solvent Extraction |
1 relatively robust extraction procedure that allows for efficient transfer of analytes into the extraction solvent |
1 time consuming; long procedure for sample extraction, with extraction times between 8 and 48 h |
2 applicable to complex sample matrices, like seafood |
2 uses a lot of solvent, of which most is toxic, and, thus, generates a lot of hazardous waste |
3 can be directly applied to unfiltered samples |
3 has a low preconcentration factor |
Supercritical Fluid Extraction (SFE) |
1 simple, faster, and high-precision extraction compared to conventional solvent extraction methods |
1 because it uses CO2 as an extractant, the scope of application is limited to nonpolar analytes |
2 uses CO2, an environmentally friendly extractant, that reduces the need for consumption of and exposure to toxic organic solvents; CO2 is non-toxic, non-flammable, and relatively cheap |
2 application in arsenic speciation is rare as a result of low extraction efficiency for highly polar or ionic compounds, which form the majority of the organoarsenicals |
3 low viscosity and diffusion coefficient, contributing to rapid mass transfer of solutions and enhanced interactions at the molecular level, which favors the solubilization process |
3 poor selectivity, which requires advanced optimization |
4 capable of extracting thermolabile species, owing to the use of CO2 as an extractant, which has a low critical temperature that allows for extractions under mild conditions, and, thus, suitable for speciation analysis |
Accelerated Solvent Extraction (ASE) |
1 analyte- and matrix-independent technique |
1 extraction efficiency asymptotically reaches a maximum, at which point the quantitative nature of extraction becomes matrix-dependent |
2 provides cleaner extracts than conventional extraction procedures |
2 no exact volume control of solvent used for extraction is provided |
3 applicable for extraction of analytes in complex matrices |
3 only fixed and relatively high-volume extraction cells are commercially available |
4 relatively short sample extraction time |
4 limited application in speciation analysis |
Microwave-Assisted Extraction (MAE) |
1 highly efficient extraction method for a wide range of sample matrices; solubility and not solvent diffusion is the only critical parameter to obtain good recovery |
1 extraction medium, microwave power, and exposure time must be carefully optimized to avoid species losses or transformation |
2 capable of hyphenation to chromatographic and spectroanalytical techniques |
2 requires polar solvents |
3 suitable for extraction of thermolabile species |
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4 supports derivatization reactions |
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5 fast and effective extraction method |
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6 environmentally friendly because of reduced solvent waste |
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Ultrasound Probe Sonication (UPS) |
1 simple extraction procedure with fewer operations and, thus, less prone to contamination |
1 being a batch system, the solvent cannot be renewed during the process; therefore, its efficiency is a function of the partitioning coefficient |
2 cavitation increases the polarity of the system, including extractants, analytes, and matrices, which increases the extraction efficiency |
2 the need for filtration and rinsing after extraction lengthens the overall duration of the process and increases solvent consumption and the risk of losses or contamination |
3 allows for addition of a co-extractant to further increase the polarity of the liquid phase |
3 particle size is a critical factor |
4 allows for the extraction of thermolabile analytes, which are altered when using conventional extraction techniques |
4 less robust because the extraction efficiency can be altered as the surface of the ultrasonic probe ages |
5 allows for extraction of a wide variety of compounds with various polarities and, therefore, can be used with any solvent |
5 lower precision, resulting from the use of an ultrasonic bath, in which energy distribution is not uniform and ultrasound energy is wasted |
6 generally an expeditious, inexpensive, and effective alternative to other extraction techniques, with the possibility of full automation |
6 not reproducible |
7 safer for acid digestion because it does not require high pressure or temperature |
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Matrix Solid-Phase Dispersion (MSPD) |
1 mild extraction technique that maintains species integrity |
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2 suitable for speciation analysis |
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3 allows for simultaneous extraction and cleanup of samples |
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4 high capability for organic analyte extraction from complex matrices |
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