Sample preparation
Sample preparation - contextSample preparation - motivationPurpose of sample preparationOverview of preparation methods
Liquid liquid extraction (LLE) Solid phase extraction (SPE) Solid phase microextraction (SPME) Purge and trap (PT) (Accelerated) Solvent extraction ((A)SE) 
Supercritical fluid extraction (SFE) Filter Techniques (FT)
Box 10 FiltrationBox 11 SorbentsBox 12 Preconcentration
Selftest 1) Polar organic solvent Answer 2) Ideal extraction procedures Answer 3) SPME Answer 4) Extraction efficiency Answer 5) Sorption capacity Answer 6) Use as little of an extraction medium as possible Answer 7) Should soil samples be grinded? Answer 8) Solvent volume Answer 9) Extracting an air sample AnswerProblems
End of chapter4) Extraction efficiency
Answers:
Extracting a water sample with X ml of solvent instead of two times X/2 ml of solvent is...
(1) ...more efficient.
No! Convince yourself and make an arbitrary model calculation. Don't forget to "pool" the extracted amounts in the case you use two consecutive extraction steps.
(2) ...does not make a difference.
That is wrong, see (1) and (2).
(3) ...less work.
That is right, but it is also less efficient.
(4) ...less efficient.
That is right. It is always more efficient to split the volume of organic solvent and then conduct separate extraction steps with the smaller volumes than one extraction step with a large volume.
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