Know your techniques_ Semi-volatile components with GC, • High levels, LLE, SPE • Trace levels, evaporate solvent_ MEPS_ • Complex matrix, clean-up_ • Polar compounds, derivatisation_ • High boilers, on-column injection_
Know your techniques_ Non-volatile components with LC, • GC is possible, derivatisation_ • High levels direct injection_ • Trace levels, SPE_ • Complex matrix, clean-up_ • Polarity, LC mode_
4Use smart calibration solutions_ Exploit the power of MS, • Isotope dilution analysis_ • Internal standards prior to prep_ • Surrogates prior to injection_ • Standard addition for complex matrices_
5Take your time & evaluate_ Developing a sample prep method is often challenging and quite frustrating. Immediate success is highly uncertain, even for experienced users.. Take your time and carefully assess all possibilities.
Definition of sorptive extraction Family of miniature extraction techniques that use polydimethyl siloxane or polyacrylate as enrichment phase_
Applications of sorptive extraction Sorptive extractions are particularly popular in scientific literature. Applications include, • Headspace extraction_ • Direct extraction_ • In-situ derivatisation_ • Passive sampling_
Typical configurations Several techiques have been introduced, • solid phase microextraction_ • stir bar sorptive extraction_ • solid phase dynamic extraction_ • single drop microextraction_
Advantages of sorptive extraction Applied configurations are simple to use and eliminate extraction solvents. After sampling, trapped components are released by heat, without partial losses (sensitivity)_
Some remarks to take into account Sorptive extraction uses equilibrium extraction, • Takes some time to complete • Non-exhaustive extraction • Equilibrium depends on matrix Preserve for clean matrices !
Comparison fiber versus stir bar Use a mixed mode SPME fiber to attain sensitivities superior to SBSE, • Fully automated_ • In a fraction of time_